New Passphrase class for safer passphrase handling in memory

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/BaseOperation.java

@@ -24,6 +24,7 @@ import org.sufficientlysecure.keychain.pgp.Progressable;
 import org.sufficientlysecure.keychain.provider.ProviderHelper;
 import org.sufficientlysecure.keychain.provider.ProviderHelper.NotFoundException;
 import org.sufficientlysecure.keychain.service.PassphraseCacheService;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -101,7 +102,7 @@ public abstract class BaseOperation implements PassphraseCacheInterface {
     }
 
     @Override
-    public String getCachedPassphrase(long subKeyId) throws NoSecretKeyException {
+    public Passphrase getCachedPassphrase(long subKeyId) throws NoSecretKeyException {
         try {
             long masterKeyId = mProviderHelper.getMasterKeyId(subKeyId);
             return getCachedPassphrase(masterKeyId, subKeyId);
@@ -111,7 +112,7 @@ public abstract class BaseOperation implements PassphraseCacheInterface {
     }
 
     @Override
-    public String getCachedPassphrase(long masterKeyId, long subKeyId) throws NoSecretKeyException {
+    public Passphrase getCachedPassphrase(long masterKeyId, long subKeyId) throws NoSecretKeyException {
         try {
             return PassphraseCacheService.getCachedPassphrase(
                     mContext, masterKeyId, subKeyId);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/CertifyOperation.java

@@ -40,6 +40,7 @@ import org.sufficientlysecure.keychain.service.CertifyActionsParcel.CertifyActio
 import org.sufficientlysecure.keychain.service.ContactSyncAdapterService;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.ArrayList;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -79,7 +80,7 @@ public class CertifyOperation extends BaseOperation {
             }
 
             // certification is always with the master key id, so use that one
-            String passphrase = getCachedPassphrase(parcel.mMasterKeyId, parcel.mMasterKeyId);
+            Passphrase passphrase = getCachedPassphrase(parcel.mMasterKeyId, parcel.mMasterKeyId);
 
             if (!certificationKey.unlock(passphrase)) {
                 log.add(LogType.MSG_CRT_ERROR_UNLOCK, 2);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/EditKeyOperation.java

@@ -35,6 +35,7 @@ import org.sufficientlysecure.keychain.service.ContactSyncAdapterService;
 import org.sufficientlysecure.keychain.service.PassphraseCacheService;
 import org.sufficientlysecure.keychain.service.SaveKeyringParcel;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.ProgressScaler;
 
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -55,7 +56,7 @@ public class EditKeyOperation extends BaseOperation {
         super(context, providerHelper, progressable, cancelled);
     }
 
-    public EditKeyResult execute(SaveKeyringParcel saveParcel, String passphrase) {
+    public EditKeyResult execute(SaveKeyringParcel saveParcel, Passphrase passphrase) {
 
         OperationLog log = new OperationLog();
         log.add(LogType.MSG_ED, 0);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/results/DecryptVerifyResult.java

@@ -22,6 +22,7 @@ import android.os.Parcel;
 
 import org.openintents.openpgp.OpenPgpMetadata;
 import org.openintents.openpgp.OpenPgpSignatureResult;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 public class DecryptVerifyResult extends OperationResult {
 
@@ -37,7 +38,7 @@ public class DecryptVerifyResult extends OperationResult {
 
     long mNfcSubKeyId;
     byte[] mNfcSessionKey;
-    String mNfcPassphrase;
+    Passphrase mNfcPassphrase;
 
     OpenPgpSignatureResult mSignatureResult;
     OpenPgpMetadata mDecryptMetadata;
@@ -53,7 +54,7 @@ public class DecryptVerifyResult extends OperationResult {
         mKeyIdPassphraseNeeded = keyIdPassphraseNeeded;
     }
 
-    public void setNfcState(long subKeyId, byte[] sessionKey, String passphrase) {
+    public void setNfcState(long subKeyId, byte[] sessionKey, Passphrase passphrase) {
         mNfcSubKeyId = subKeyId;
         mNfcSessionKey = sessionKey;
         mNfcPassphrase = passphrase;
@@ -67,7 +68,7 @@ public class DecryptVerifyResult extends OperationResult {
         return mNfcSessionKey;
     }
 
-    public String getNfcPassphrase() {
+    public Passphrase getNfcPassphrase() {
         return mNfcPassphrase;
     }
 
@@ -109,7 +110,7 @@ public class DecryptVerifyResult extends OperationResult {
         mSignatureResult = source.readParcelable(OpenPgpSignatureResult.class.getClassLoader());
         mDecryptMetadata = source.readParcelable(OpenPgpMetadata.class.getClassLoader());
         mNfcSessionKey = source.readInt() != 0 ? source.createByteArray() : null;
-        mNfcPassphrase = source.readString();
+        mNfcPassphrase = source.readParcelable(Passphrase.class.getClassLoader());
     }
 
     public int describeContents() {
@@ -127,7 +128,7 @@ public class DecryptVerifyResult extends OperationResult {
         } else {
             dest.writeInt(0);
         }
-        dest.writeString(mNfcPassphrase);
+        dest.writeParcelable(mNfcPassphrase, flags);
     }
 
     public static final Creator<DecryptVerifyResult> CREATOR = new Creator<DecryptVerifyResult>() {

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/operations/results/PgpSignEncryptResult.java

@@ -19,6 +19,8 @@ package org.sufficientlysecure.keychain.operations.results;
 
 import android.os.Parcel;
 
+import org.sufficientlysecure.keychain.util.Passphrase;
+
 import java.util.Date;
 
 public class PgpSignEncryptResult extends OperationResult {
@@ -36,7 +38,7 @@ public class PgpSignEncryptResult extends OperationResult {
     byte[] mNfcHash;
     int mNfcAlgo;
     Date mNfcTimestamp;
-    String mNfcPassphrase;
+    Passphrase mNfcPassphrase;
     byte[] mDetachedSignature;
 
     public long getKeyIdPassphraseNeeded() {
@@ -47,7 +49,7 @@ public class PgpSignEncryptResult extends OperationResult {
         mKeyIdPassphraseNeeded = keyIdPassphraseNeeded;
     }
 
-    public void setNfcData(long nfcKeyId, byte[] nfcHash, int nfcAlgo, Date nfcTimestamp, String passphrase) {
+    public void setNfcData(long nfcKeyId, byte[] nfcHash, int nfcAlgo, Date nfcTimestamp, Passphrase passphrase) {
         mNfcKeyId = nfcKeyId;
         mNfcHash = nfcHash;
         mNfcAlgo = nfcAlgo;
@@ -75,7 +77,7 @@ public class PgpSignEncryptResult extends OperationResult {
         return mNfcTimestamp;
     }
 
-    public String getNfcPassphrase() {
+    public Passphrase getNfcPassphrase() {
         return mNfcPassphrase;
     }
 

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/CanonicalizedSecretKey.java

@@ -41,6 +41,7 @@ import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.pgp.exception.PgpGeneralException;
 import org.sufficientlysecure.keychain.pgp.exception.PgpKeyNotFoundException;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.ArrayList;
 import java.util.Date;
@@ -149,7 +150,7 @@ public class CanonicalizedSecretKey extends CanonicalizedPublicKey {
     /**
      * Returns true on right passphrase
      */
-    public boolean unlock(String passphrase) throws PgpGeneralException {
+    public boolean unlock(Passphrase passphrase) throws PgpGeneralException {
         // handle keys on OpenPGP cards like they were unlocked
         if (mSecretKey.getS2K() != null
                 && mSecretKey.getS2K().getType() == S2K.GNU_DUMMY_S2K
@@ -161,7 +162,7 @@ public class CanonicalizedSecretKey extends CanonicalizedPublicKey {
         // try to extract keys using the passphrase
         try {
             PBESecretKeyDecryptor keyDecryptor = new JcePBESecretKeyDecryptorBuilder().setProvider(
-                    Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.toCharArray());
+                    Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.getCharArray());
             mPrivateKey = mSecretKey.extractPrivateKey(keyDecryptor);
             mPrivateKeyState = PRIVATE_KEY_STATE_UNLOCKED;
         } catch (PGPException e) {

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PassphraseCacheInterface.java

@@ -18,14 +18,16 @@
 
 package org.sufficientlysecure.keychain.pgp;
 
+import org.sufficientlysecure.keychain.util.Passphrase;
+
 public interface PassphraseCacheInterface {
     public static class NoSecretKeyException extends Exception {
         public NoSecretKeyException() {
         }
     }
 
-    public String getCachedPassphrase(long subKeyId) throws NoSecretKeyException;
+    public Passphrase getCachedPassphrase(long subKeyId) throws NoSecretKeyException;
 
-    public String getCachedPassphrase(long masterKeyId, long subKeyId) throws NoSecretKeyException;
+    public Passphrase getCachedPassphrase(long masterKeyId, long subKeyId) throws NoSecretKeyException;
 
 }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpDecryptVerify.java

@@ -60,6 +60,7 @@ import org.sufficientlysecure.keychain.provider.ProviderHelper;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
 import org.sufficientlysecure.keychain.util.InputData;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.ProgressScaler;
 
 import java.io.BufferedInputStream;
@@ -83,7 +84,7 @@ public class PgpDecryptVerify extends BaseOperation {
     private OutputStream mOutStream;
 
     private boolean mAllowSymmetricDecryption;
-    private String mPassphrase;
+    private Passphrase mPassphrase;
     private Set<Long> mAllowedKeyIds;
     private boolean mDecryptMetadataOnly;
     private byte[] mDecryptedSessionKey;
@@ -118,7 +119,7 @@ public class PgpDecryptVerify extends BaseOperation {
         private OutputStream mOutStream = null;
         private Progressable mProgressable = null;
         private boolean mAllowSymmetricDecryption = true;
-        private String mPassphrase = null;
+        private Passphrase mPassphrase = null;
         private Set<Long> mAllowedKeyIds = null;
         private boolean mDecryptMetadataOnly = false;
         private byte[] mDecryptedSessionKey = null;
@@ -159,7 +160,7 @@ public class PgpDecryptVerify extends BaseOperation {
             return this;
         }
 
-        public Builder setPassphrase(String passphrase) {
+        public Builder setPassphrase(Passphrase passphrase) {
             mPassphrase = passphrase;
             return this;
         }
@@ -572,7 +573,7 @@ public class PgpDecryptVerify extends BaseOperation {
                     .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build();
             PBEDataDecryptorFactory decryptorFactory = new JcePBEDataDecryptorFactoryBuilder(
                     digestCalcProvider).setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(
-                    mPassphrase.toCharArray());
+                    mPassphrase.getCharArray());
 
             clear = encryptedDataSymmetric.getDataStream(decryptorFactory);
             encryptedData = encryptedDataSymmetric;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyOperation.java

@@ -57,6 +57,7 @@ import org.sufficientlysecure.keychain.service.SaveKeyringParcel.SubkeyAdd;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
 import org.sufficientlysecure.keychain.util.IterableIterator;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.Primes;
 import org.sufficientlysecure.keychain.util.ProgressScaler;
 
@@ -316,7 +317,7 @@ public class PgpKeyOperation {
                     masterSecretKey.getEncoded(), new JcaKeyFingerprintCalculator());
 
             subProgressPush(50, 100);
-            return internal(sKR, masterSecretKey, add.mFlags, add.mExpiry, saveParcel, "", log);
+            return internal(sKR, masterSecretKey, add.mFlags, add.mExpiry, saveParcel, new Passphrase(), log);
 
         } catch (PGPException e) {
             log.add(LogType.MSG_CR_ERROR_INTERNAL_PGP, indent);
@@ -348,7 +349,7 @@ public class PgpKeyOperation {
      *
      */
     public PgpEditKeyResult modifySecretKeyRing(CanonicalizedSecretKeyRing wsKR, SaveKeyringParcel saveParcel,
-                                               String passphrase) {
+                                                Passphrase passphrase) {
 
         OperationLog log = new OperationLog();
         int indent = 0;
@@ -404,7 +405,7 @@ public class PgpKeyOperation {
 
     private PgpEditKeyResult internal(PGPSecretKeyRing sKR, PGPSecretKey masterSecretKey,
                                      int masterKeyFlags, long masterKeyExpiry,
-                                     SaveKeyringParcel saveParcel, String passphrase,
+                                     SaveKeyringParcel saveParcel, Passphrase passphrase,
                                      OperationLog log) {
 
         int indent = 1;
@@ -420,7 +421,7 @@ public class PgpKeyOperation {
         {
             try {
                 PBESecretKeyDecryptor keyDecryptor = new JcePBESecretKeyDecryptorBuilder().setProvider(
-                        Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.toCharArray());
+                        Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.getCharArray());
                 masterPrivateKey = masterSecretKey.extractPrivateKey(keyDecryptor);
             } catch (PGPException e) {
                 log.add(LogType.MSG_MF_UNLOCK_ERROR, indent + 1);
@@ -839,7 +840,7 @@ public class PgpKeyOperation {
                     PBESecretKeyEncryptor keyEncryptor = new JcePBESecretKeyEncryptorBuilder(
                             PgpConstants.SECRET_KEY_ENCRYPTOR_SYMMETRIC_ALGO, encryptorHashCalc,
                             PgpConstants.SECRET_KEY_ENCRYPTOR_S2K_COUNT)
-                            .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.toCharArray());
+                            .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.getCharArray());
 
                     PGPDigestCalculator sha1Calc = new JcaPGPDigestCalculatorProviderBuilder()
                             .build().get(PgpConstants.SECRET_KEY_SIGNATURE_CHECKSUM_HASH_ALGO);
@@ -967,7 +968,7 @@ public class PgpKeyOperation {
             PGPSecretKeyRing sKR,
             PGPPublicKey masterPublicKey,
             PGPPrivateKey masterPrivateKey,
-            String passphrase,
+            Passphrase passphrase,
             ChangeUnlockParcel newUnlock,
             OperationLog log, int indent) throws PGPException {
 
@@ -1051,20 +1052,20 @@ public class PgpKeyOperation {
     private static PGPSecretKeyRing applyNewPassphrase(
             PGPSecretKeyRing sKR,
             PGPPublicKey masterPublicKey,
-            String passphrase,
+            Passphrase passphrase,
-            String newPassphrase,
+            Passphrase newPassphrase,
             OperationLog log, int indent) throws PGPException {
 
         PGPDigestCalculator encryptorHashCalc = new JcaPGPDigestCalculatorProviderBuilder().build()
                 .get(PgpConstants.SECRET_KEY_ENCRYPTOR_HASH_ALGO);
         PBESecretKeyDecryptor keyDecryptor = new JcePBESecretKeyDecryptorBuilder().setProvider(
-                Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.toCharArray());
+                Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(passphrase.getCharArray());
         // Build key encryptor based on new passphrase
         PBESecretKeyEncryptor keyEncryptorNew = new JcePBESecretKeyEncryptorBuilder(
                 PgpConstants.SECRET_KEY_ENCRYPTOR_SYMMETRIC_ALGO, encryptorHashCalc,
                 PgpConstants.SECRET_KEY_ENCRYPTOR_S2K_COUNT)
                 .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(
-                        newPassphrase.toCharArray());
+                        newPassphrase.getCharArray());
 
         // noinspection unchecked
         for (PGPSecretKey sKey : new IterableIterator<PGPSecretKey>(sKR.getSecretKeys())) {
@@ -1295,11 +1296,11 @@ public class PgpKeyOperation {
 
     private static PGPSignature generateSubkeyBindingSignature(
             PGPPublicKey masterPublicKey, PGPPrivateKey masterPrivateKey,
-            PGPSecretKey sKey, PGPPublicKey pKey, int flags, long expiry, String passphrase)
+            PGPSecretKey sKey, PGPPublicKey pKey, int flags, long expiry, Passphrase passphrase)
             throws IOException, PGPException, SignatureException {
         PBESecretKeyDecryptor keyDecryptor = new JcePBESecretKeyDecryptorBuilder()
                 .setProvider(Constants.BOUNCY_CASTLE_PROVIDER_NAME).build(
-                        passphrase.toCharArray());
+                        passphrase.getCharArray());
         PGPPrivateKey subPrivateKey = sKey.extractPrivateKey(keyDecryptor);
         return generateSubkeyBindingSignature(masterPublicKey, masterPrivateKey, subPrivateKey,
                 pKey, flags, expiry);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptInput.java

@@ -20,6 +20,7 @@ package org.sufficientlysecure.keychain.pgp;
 
 import org.spongycastle.bcpg.CompressionAlgorithmTags;
 import org.sufficientlysecure.keychain.Constants;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.Date;
 
@@ -29,12 +30,12 @@ public class PgpSignEncryptInput {
     protected boolean mEnableAsciiArmorOutput = false;
     protected int mCompressionId = CompressionAlgorithmTags.UNCOMPRESSED;
     protected long[] mEncryptionMasterKeyIds = null;
-    protected String mSymmetricPassphrase = null;
+    protected Passphrase mSymmetricPassphrase = null;
     protected int mSymmetricEncryptionAlgorithm = PgpConstants.OpenKeychainSymmetricKeyAlgorithmTags.USE_PREFERRED;
     protected long mSignatureMasterKeyId = Constants.key.none;
     protected Long mSignatureSubKeyId = null;
     protected int mSignatureHashAlgorithm = PgpConstants.OpenKeychainHashAlgorithmTags.USE_PREFERRED;
-    protected String mSignaturePassphrase = null;
+    protected Passphrase mSignaturePassphrase = null;
     protected long mAdditionalEncryptId = Constants.key.none;
     protected byte[] mNfcSignedHash = null;
     protected Date mNfcCreationTimestamp = null;
@@ -73,11 +74,11 @@ public class PgpSignEncryptInput {
         return this;
     }
 
-    public String getSignaturePassphrase() {
+    public Passphrase getSignaturePassphrase() {
         return mSignaturePassphrase;
     }
 
-    public PgpSignEncryptInput setSignaturePassphrase(String signaturePassphrase) {
+    public PgpSignEncryptInput setSignaturePassphrase(Passphrase signaturePassphrase) {
         mSignaturePassphrase = signaturePassphrase;
         return this;
     }
@@ -118,11 +119,11 @@ public class PgpSignEncryptInput {
         return this;
     }
 
-    public String getSymmetricPassphrase() {
+    public Passphrase getSymmetricPassphrase() {
         return mSymmetricPassphrase;
     }
 
-    public PgpSignEncryptInput setSymmetricPassphrase(String symmetricPassphrase) {
+    public PgpSignEncryptInput setSymmetricPassphrase(Passphrase symmetricPassphrase) {
         mSymmetricPassphrase = symmetricPassphrase;
         return this;
     }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpSignEncryptOperation.java

@@ -243,7 +243,7 @@ public class PgpSignEncryptOperation extends BaseOperation {
                 log.add(LogType.MSG_PSE_SYMMETRIC, indent);
 
                 JcePBEKeyEncryptionMethodGenerator symmetricEncryptionGenerator =
-                        new JcePBEKeyEncryptionMethodGenerator(input.getSymmetricPassphrase().toCharArray());
+                        new JcePBEKeyEncryptionMethodGenerator(input.getSymmetricPassphrase().getCharArray());
                 cPk.addMethod(symmetricEncryptionGenerator);
             } else {
                 log.add(LogType.MSG_PSE_ASYMMETRIC, indent);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/SignEncryptParcel.java

@@ -22,6 +22,8 @@ import android.net.Uri;
 import android.os.Parcel;
 import android.os.Parcelable;
 
+import org.sufficientlysecure.keychain.util.Passphrase;
+
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -57,12 +59,12 @@ public class SignEncryptParcel extends PgpSignEncryptInput implements Parcelable
         mEnableAsciiArmorOutput  = src.readInt() == 1;
         mCompressionId = src.readInt();
         mEncryptionMasterKeyIds = src.createLongArray();
-        mSymmetricPassphrase = src.readString();
+        mSymmetricPassphrase = src.readParcelable(Passphrase.class.getClassLoader());
         mSymmetricEncryptionAlgorithm = src.readInt();
         mSignatureMasterKeyId = src.readLong();
         mSignatureSubKeyId = src.readInt() == 1 ? src.readLong() : null;
         mSignatureHashAlgorithm = src.readInt();
-        mSignaturePassphrase = src.readString();
+        mSignaturePassphrase = src.readParcelable(Passphrase.class.getClassLoader());
         mAdditionalEncryptId = src.readLong();
         mNfcSignedHash = src.createByteArray();
         mNfcCreationTimestamp = src.readInt() == 1 ? new Date(src.readLong()) : null;
@@ -112,7 +114,7 @@ public class SignEncryptParcel extends PgpSignEncryptInput implements Parcelable
         dest.writeInt(mEnableAsciiArmorOutput ? 1 : 0);
         dest.writeInt(mCompressionId);
         dest.writeLongArray(mEncryptionMasterKeyIds);
-        dest.writeString(mSymmetricPassphrase);
+        dest.writeParcelable(mSymmetricPassphrase, flags);
         dest.writeInt(mSymmetricEncryptionAlgorithm);
         dest.writeLong(mSignatureMasterKeyId);
         if (mSignatureSubKeyId != null) {
@@ -122,7 +124,7 @@ public class SignEncryptParcel extends PgpSignEncryptInput implements Parcelable
             dest.writeInt(0);
         }
         dest.writeInt(mSignatureHashAlgorithm);
-        dest.writeString(mSignaturePassphrase);
+        dest.writeParcelable(mSignaturePassphrase, flags);
         dest.writeLong(mAdditionalEncryptId);
         dest.writeByteArray(mNfcSignedHash);
         if (mNfcCreationTimestamp != null) {

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/remote/OpenPgpService.java

@@ -54,6 +54,7 @@ import org.sufficientlysecure.keychain.ui.PassphraseDialogActivity;
 import org.sufficientlysecure.keychain.ui.ViewKeyActivity;
 import org.sufficientlysecure.keychain.util.InputData;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -179,7 +180,7 @@ public class OpenPgpService extends RemoteService {
         return result;
     }
 
-    private PendingIntent getNfcSignPendingIntent(Intent data, long keyId, String pin, byte[] hashToSign, int hashAlgo) {
+    private PendingIntent getNfcSignPendingIntent(Intent data, long keyId, Passphrase pin, byte[] hashToSign, int hashAlgo) {
         // build PendingIntent for Yubikey NFC operations
         Intent intent = new Intent(getBaseContext(), NfcActivity.class);
         intent.setAction(NfcActivity.ACTION_SIGN_HASH);
@@ -195,7 +196,7 @@ public class OpenPgpService extends RemoteService {
                 PendingIntent.FLAG_CANCEL_CURRENT);
     }
 
-    private PendingIntent getNfcDecryptPendingIntent(Intent data, long subKeyId, String pin, byte[] encryptedSessionKey) {
+    private PendingIntent getNfcDecryptPendingIntent(Intent data, long subKeyId, Passphrase pin, byte[] encryptedSessionKey) {
         // build PendingIntent for Yubikey NFC operations
         Intent intent = new Intent(getBaseContext(), NfcActivity.class);
         intent.setAction(NfcActivity.ACTION_DECRYPT_SESSION_KEY);
@@ -508,7 +509,7 @@ public class OpenPgpService extends RemoteService {
                         KeychainContract.ApiAllowedKeys.buildBaseUri(currentPkg));
             }
 
-            String passphrase = data.getStringExtra(OpenPgpApi.EXTRA_PASSPHRASE);
+            Passphrase passphrase = data.getParcelableExtra(OpenPgpApi.EXTRA_PASSPHRASE);
             long inputLength = is.available();
             InputData inputData = new InputData(is, inputLength);
 

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/KeychainIntentService.java

@@ -65,6 +65,7 @@ import org.sufficientlysecure.keychain.util.FileHelper;
 import org.sufficientlysecure.keychain.util.InputData;
 import org.sufficientlysecure.keychain.util.Log;
 import org.sufficientlysecure.keychain.util.ParcelableFileCache;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -281,7 +282,7 @@ public class KeychainIntentService extends IntentService implements Progressable
 
                 try {
                 /* Input */
-                    String passphrase = data.getString(DECRYPT_PASSPHRASE);
+                    Passphrase passphrase = data.getParcelable(DECRYPT_PASSPHRASE);
                     byte[] nfcDecryptedSessionKey = data.getByteArray(DECRYPT_NFC_DECRYPTED_SESSION_KEY);
 
                     InputData inputData = createDecryptInputData(data);
@@ -411,7 +412,7 @@ public class KeychainIntentService extends IntentService implements Progressable
 
                 try {
                 /* Input */
-                    String passphrase = data.getString(DECRYPT_PASSPHRASE);
+                    Passphrase passphrase = data.getParcelable(DECRYPT_PASSPHRASE);
                     byte[] nfcDecryptedSessionKey = data.getByteArray(DECRYPT_NFC_DECRYPTED_SESSION_KEY);
 
                     InputData inputData = createDecryptInputData(data);
@@ -469,7 +470,7 @@ public class KeychainIntentService extends IntentService implements Progressable
 
                 // Input
                 SaveKeyringParcel saveParcel = data.getParcelable(EDIT_KEYRING_PARCEL);
-                String passphrase = data.getString(EDIT_KEYRING_PASSPHRASE);
+                Passphrase passphrase = data.getParcelable(EDIT_KEYRING_PASSPHRASE);
 
                 // Operation
                 EditKeyOperation op = new EditKeyOperation(this, providerHelper, this, mActionCanceled);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/PassphraseCacheService.java

@@ -43,6 +43,7 @@ import org.sufficientlysecure.keychain.pgp.CanonicalizedSecretKey.SecretKeyType;
 import org.sufficientlysecure.keychain.provider.CachedPublicKeyRing;
 import org.sufficientlysecure.keychain.provider.ProviderHelper;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.Preferences;
 
 import java.util.Date;
@@ -121,7 +122,7 @@ public class PassphraseCacheService extends Service {
      * new events to the alarm manager for new passphrases to let them timeout in the future.
      */
     public static void addCachedPassphrase(Context context, long masterKeyId, long subKeyId,
-                                           String passphrase,
+                                           Passphrase passphrase,
                                            String primaryUserId) {
         Log.d(Constants.TAG, "PassphraseCacheService.cacheNewPassphrase() for " + masterKeyId);
 
@@ -143,7 +144,7 @@ public class PassphraseCacheService extends Service {
 
      * @return passphrase or null (if no passphrase is cached for this keyId)
      */
-    public static String getCachedPassphrase(Context context, long masterKeyId, long subKeyId) throws KeyNotFoundException {
+    public static Passphrase getCachedPassphrase(Context context, long masterKeyId, long subKeyId) throws KeyNotFoundException {
         Log.d(Constants.TAG, "PassphraseCacheService.getCachedPassphrase() for masterKeyId "
                 + masterKeyId + ", subKeyId " + subKeyId);
 
@@ -190,7 +191,9 @@ public class PassphraseCacheService extends Service {
 
         switch (returnMessage.what) {
             case MSG_PASSPHRASE_CACHE_GET_OKAY:
-                return returnMessage.getData().getString(EXTRA_PASSPHRASE);
+                Bundle returnData = returnMessage.getData();
+                returnData.setClassLoader(context.getClassLoader());
+                return returnData.getParcelable(EXTRA_PASSPHRASE);
             case MSG_PASSPHRASE_CACHE_GET_KEY_NOT_FOUND:
                 throw new KeyNotFoundException();
             default:
@@ -202,11 +205,11 @@ public class PassphraseCacheService extends Service {
     /**
      * Internal implementation to get cached passphrase.
      */
-    private String getCachedPassphraseImpl(long masterKeyId, long subKeyId) throws ProviderHelper.NotFoundException {
+    private Passphrase getCachedPassphraseImpl(long masterKeyId, long subKeyId) throws ProviderHelper.NotFoundException {
         // passphrase for symmetric encryption?
         if (masterKeyId == Constants.key.symmetric) {
             Log.d(Constants.TAG, "PassphraseCacheService.getCachedPassphraseImpl() for symmetric encryption");
-            String cachedPassphrase = mPassphraseCache.get(Constants.key.symmetric).getPassphrase();
+            Passphrase cachedPassphrase = mPassphraseCache.get(Constants.key.symmetric).getPassphrase();
             if (cachedPassphrase == null) {
                 return null;
             }
@@ -232,13 +235,13 @@ public class PassphraseCacheService extends Service {
             case DIVERT_TO_CARD:
                 if (Preferences.getPreferences(this).useDefaultYubikeyPin()) {
                     Log.d(Constants.TAG, "PassphraseCacheService: Using default Yubikey PIN: 123456");
-                    return "123456"; // default Yubikey PIN, see http://www.yubico.com/2012/12/yubikey-neo-openpgp/
+                    return new Passphrase("123456"); // default Yubikey PIN, see http://www.yubico.com/2012/12/yubikey-neo-openpgp/
                 } else {
                     Log.d(Constants.TAG, "PassphraseCacheService: NOT using default Yubikey PIN");
                     break;
                 }
             case PASSPHRASE_EMPTY:
-                return "";
+                return new Passphrase("");
             case UNAVAILABLE:
                 throw new ProviderHelper.NotFoundException("secret key for this subkey is not available");
             case GNU_DUMMY:
@@ -331,7 +334,7 @@ public class PassphraseCacheService extends Service {
                 long masterKeyId = intent.getLongExtra(EXTRA_KEY_ID, -1);
                 long subKeyId = intent.getLongExtra(EXTRA_SUBKEY_ID, -1);
 
-                String passphrase = intent.getStringExtra(EXTRA_PASSPHRASE);
+                Passphrase passphrase = intent.getParcelableExtra(EXTRA_PASSPHRASE);
                 String primaryUserID = intent.getStringExtra(EXTRA_USER_ID);
 
                 Log.d(Constants.TAG,
@@ -373,10 +376,10 @@ public class PassphraseCacheService extends Service {
                         Log.e(Constants.TAG, "PassphraseCacheService: Bad request, missing masterKeyId or subKeyId!");
                         msg.what = MSG_PASSPHRASE_CACHE_GET_KEY_NOT_FOUND;
                     } else {
-                        String passphrase = getCachedPassphraseImpl(masterKeyId, subKeyId);
+                        Passphrase passphrase = getCachedPassphraseImpl(masterKeyId, subKeyId);
                         msg.what = MSG_PASSPHRASE_CACHE_GET_OKAY;
                         Bundle bundle = new Bundle();
-                        bundle.putString(EXTRA_PASSPHRASE, passphrase);
+                        bundle.putParcelable(EXTRA_PASSPHRASE, passphrase);
                         msg.setData(bundle);
                     }
                 } catch (ProviderHelper.NotFoundException e) {
@@ -412,7 +415,10 @@ public class PassphraseCacheService extends Service {
      * Called when one specific passphrase for keyId timed out
      */
     private void timeout(Context context, long keyId) {
-        // remove passphrase corresponding to keyId from memory
+        CachedPassphrase cPass = mPassphraseCache.get(keyId);
+        // clean internal char[] from memory!
+        cPass.getPassphrase().removeFromMemory();
+        // remove passphrase object
         mPassphraseCache.remove(keyId);
 
         Log.d(Constants.TAG, "PassphraseCacheService Timeout of keyId " + keyId + ", removed from memory!");
@@ -517,9 +523,9 @@ public class PassphraseCacheService extends Service {
 
     public class CachedPassphrase {
         private String primaryUserID;
-        private String passphrase;
+        private Passphrase passphrase;
 
-        public CachedPassphrase(String passphrase, String primaryUserID) {
+        public CachedPassphrase(Passphrase passphrase, String primaryUserID) {
             setPassphrase(passphrase);
             setPrimaryUserID(primaryUserID);
         }
@@ -528,7 +534,7 @@ public class PassphraseCacheService extends Service {
             return primaryUserID;
         }
 
-        public String getPassphrase() {
+        public Passphrase getPassphrase() {
             return passphrase;
         }
 
@@ -536,7 +542,7 @@ public class PassphraseCacheService extends Service {
             this.primaryUserID = primaryUserID;
         }
 
-        public void setPassphrase(String passphrase) {
+        public void setPassphrase(Passphrase passphrase) {
             this.passphrase = passphrase;
         }
     }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/service/SaveKeyringParcel.java

@@ -22,6 +22,7 @@ import android.os.Parcel;
 import android.os.Parcelable;
 
 import org.sufficientlysecure.keychain.pgp.WrappedUserAttribute;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.io.Serializable;
 import java.util.ArrayList;
@@ -296,33 +297,30 @@ public class SaveKeyringParcel implements Parcelable {
     public static class ChangeUnlockParcel implements Parcelable {
 
         // The new passphrase to use
-        public final String mNewPassphrase;
+        public final Passphrase mNewPassphrase;
         // A new pin to use. Must only contain [0-9]+
-        public final String mNewPin;
+        public final Passphrase mNewPin;
 
-        public ChangeUnlockParcel(String newPassphrase) {
+        public ChangeUnlockParcel(Passphrase newPassphrase) {
             this(newPassphrase, null);
         }
-        public ChangeUnlockParcel(String newPassphrase, String newPin) {
+        public ChangeUnlockParcel(Passphrase newPassphrase, Passphrase newPin) {
             if (newPassphrase == null && newPin == null) {
                 throw new RuntimeException("Cannot set both passphrase and pin. THIS IS A BUG!");
             }
-            if (newPin != null && !newPin.matches("[0-9]+")) {
-                throw new RuntimeException("Pin must be numeric digits only. THIS IS A BUG!");
-            }
             mNewPassphrase = newPassphrase;
             mNewPin = newPin;
         }
 
         public ChangeUnlockParcel(Parcel source) {
-            mNewPassphrase = source.readString();
+            mNewPassphrase = source.readParcelable(Passphrase.class.getClassLoader());
-            mNewPin = source.readString();
+            mNewPin = source.readParcelable(Passphrase.class.getClassLoader());
         }
 
         @Override
         public void writeToParcel(Parcel destination, int flags) {
-            destination.writeString(mNewPassphrase);
+            destination.writeParcelable(mNewPassphrase, flags);
-            destination.writeString(mNewPin);
+            destination.writeParcelable(mNewPin, flags);
         }
 
         @Override

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CertifyKeyFragment.java

@@ -62,6 +62,7 @@ import org.sufficientlysecure.keychain.ui.util.Notify;
 import org.sufficientlysecure.keychain.ui.widget.CertifyKeySpinner;
 import org.sufficientlysecure.keychain.ui.widget.KeySpinner;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.Preferences;
 
 import java.lang.reflect.Method;
@@ -318,7 +319,7 @@ public class CertifyKeyFragment extends LoaderFragment
      */
     private void initiateCertifying() {
         // get the user's passphrase for this key (if required)
-        String passphrase;
+        Passphrase passphrase;
         try {
             passphrase = PassphraseCacheService.getCachedPassphrase(getActivity(), mSignMasterKeyId, mSignMasterKeyId);
         } catch (PassphraseCacheService.KeyNotFoundException e) {
@@ -341,7 +342,6 @@ public class CertifyKeyFragment extends LoaderFragment
         switch (requestCode) {
             case REQUEST_CODE_PASSPHRASE: {
                 if (resultCode == Activity.RESULT_OK && data != null) {
-                    String passphrase = data.getStringExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
                     startCertifying();
                 }
                 return;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyActivity.java

@@ -23,11 +23,20 @@ import android.support.v4.app.FragmentTransaction;
 
 import org.sufficientlysecure.keychain.R;
 
+import java.util.ArrayList;
+
 public class CreateKeyActivity extends BaseActivity {
 
     public static final String EXTRA_NAME = "name";
     public static final String EXTRA_EMAIL = "email";
 
+    public class State {
+        String name;
+        String email;
+        ArrayList<String> additionalEmails;
+        char[] passphrase;
+    }
+
     public static enum FragAction {
         START,
         TO_RIGHT,
@@ -44,7 +53,7 @@ public class CreateKeyActivity extends BaseActivity {
                         getIntent().getStringExtra(EXTRA_NAME),
                         getIntent().getStringExtra(EXTRA_EMAIL)
                 );
-        loadFragment(null, frag, FragAction.START);
+        loadFragment(savedInstanceState, frag, FragAction.START);
     }
 
     @Override

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyEmailFragment.java

@@ -85,7 +85,7 @@ public class CreateKeyEmailFragment extends Fragment {
      */
     private static boolean isEditTextNotEmpty(Context context, EditText editText) {
         boolean output = true;
-        if (editText.getText().toString().length() == 0) {
+        if (editText.getText().length() == 0) {
             editText.setError(context.getString(R.string.create_key_empty));
             editText.requestFocus();
             output = false;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyFinalFragment.java

@@ -45,6 +45,7 @@ import org.sufficientlysecure.keychain.service.SaveKeyringParcel.Algorithm;
 import org.sufficientlysecure.keychain.service.SaveKeyringParcel.ChangeUnlockParcel;
 import org.sufficientlysecure.keychain.ui.CreateKeyActivity.FragAction;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.Preferences;
 
 import java.util.ArrayList;
@@ -72,7 +73,7 @@ public class CreateKeyFinalFragment extends Fragment {
     String mName;
     String mEmail;
     ArrayList<String> mAdditionalEmails;
-    String mPassphrase;
+    Passphrase mPassphrase;
 
     SaveKeyringParcel mSaveKeyringParcel;
 
@@ -81,14 +82,14 @@ public class CreateKeyFinalFragment extends Fragment {
      */
     public static CreateKeyFinalFragment newInstance(String name, String email,
                                                      ArrayList<String> additionalEmails,
-                                                     String passphrase) {
+                                                     Passphrase passphrase) {
         CreateKeyFinalFragment frag = new CreateKeyFinalFragment();
 
         Bundle args = new Bundle();
         args.putString(ARG_NAME, name);
         args.putString(ARG_EMAIL, email);
         args.putStringArrayList(ARG_ADDITIONAL_EMAILS, additionalEmails);
-        args.putString(ARG_PASSPHRASE, passphrase);
+        args.putParcelable(ARG_PASSPHRASE, passphrase);
 
         frag.setArguments(args);
 
@@ -111,7 +112,7 @@ public class CreateKeyFinalFragment extends Fragment {
         mName = getArguments().getString(ARG_NAME);
         mEmail = getArguments().getString(ARG_EMAIL);
         mAdditionalEmails = getArguments().getStringArrayList(ARG_ADDITIONAL_EMAILS);
-        mPassphrase = getArguments().getString(ARG_PASSPHRASE);
+        mPassphrase = getArguments().getParcelable(ARG_PASSPHRASE);
 
         // set values
         mNameEdit.setText(mName);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyNameFragment.java

@@ -68,7 +68,7 @@ public class CreateKeyNameFragment extends Fragment {
      */
     private static boolean isEditTextNotEmpty(Context context, EditText editText) {
         boolean output = true;
-        if (editText.getText().toString().length() == 0) {
+        if (editText.getText().length() == 0) {
             editText.setError(context.getString(R.string.create_key_empty));
             editText.requestFocus();
             output = false;
@@ -79,19 +79,6 @@ public class CreateKeyNameFragment extends Fragment {
         return output;
     }
 
-    private static boolean areEditTextsEqual(Context context, EditText editText1, EditText editText2) {
-        boolean output = true;
-        if (!editText1.getText().toString().equals(editText2.getText().toString())) {
-            editText2.setError(context.getString(R.string.create_key_passphrases_not_equal));
-            editText2.requestFocus();
-            output = false;
-        } else {
-            editText2.setError(null);
-        }
-
-        return output;
-    }
-
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View view = inflater.inflate(R.layout.create_key_name_fragment, container, false);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/CreateKeyPassphraseFragment.java

@@ -34,6 +34,7 @@ import android.widget.EditText;
 import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.ui.CreateKeyActivity.FragAction;
 import org.sufficientlysecure.keychain.ui.widget.PassphraseEditText;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.ArrayList;
 
@@ -83,7 +84,7 @@ public class CreateKeyPassphraseFragment extends Fragment {
      */
     private static boolean isEditTextNotEmpty(Context context, EditText editText) {
         boolean output = true;
-        if (editText.getText().toString().length() == 0) {
+        if (editText.getText().length() == 0) {
             editText.setError(context.getString(R.string.create_key_empty));
             editText.requestFocus();
             output = false;
@@ -95,11 +96,13 @@ public class CreateKeyPassphraseFragment extends Fragment {
     }
 
     private static boolean areEditTextsEqual(Context context, EditText editText1, EditText editText2) {
-        boolean output = true;
+        Passphrase p1 = new Passphrase(editText1);
-        if (!editText1.getText().toString().equals(editText2.getText().toString())) {
+        Passphrase p2 = new Passphrase(editText2);
+        boolean output = (p1.equals(p2));
+
+        if (!output) {
             editText2.setError(context.getString(R.string.create_key_passphrases_not_equal));
             editText2.requestFocus();
-            output = false;
         } else {
             editText2.setError(null);
         }
@@ -171,7 +174,7 @@ public class CreateKeyPassphraseFragment extends Fragment {
                             mName,
                             mEmail,
                             mAdditionalEmails,
-                            mPassphraseEdit.getText().toString()
+                            new Passphrase(mPassphraseEdit.getText())
                     );
 
             hideKeyboard();

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/DecryptFilesFragment.java

@@ -191,7 +191,7 @@ public class DecryptFilesFragment extends DecryptFragment {
         data.putInt(KeychainIntentService.TARGET, IOType.URI.ordinal());
         data.putParcelable(KeychainIntentService.ENCRYPT_DECRYPT_OUTPUT_URI, mOutputUri);
 
-        data.putString(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
+        data.putParcelable(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
         data.putByteArray(KeychainIntentService.DECRYPT_NFC_DECRYPTED_SESSION_KEY, mNfcDecryptedSessionKey);
 
         intent.putExtra(KeychainIntentService.EXTRA_DATA, data);
@@ -265,7 +265,7 @@ public class DecryptFilesFragment extends DecryptFragment {
         data.putInt(KeychainIntentService.TARGET, IOType.URI.ordinal());
         data.putParcelable(KeychainIntentService.ENCRYPT_DECRYPT_OUTPUT_URI, mOutputUri);
 
-        data.putString(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
+        data.putParcelable(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
         data.putByteArray(KeychainIntentService.DECRYPT_NFC_DECRYPTED_SESSION_KEY, mNfcDecryptedSessionKey);
 
         intent.putExtra(KeychainIntentService.EXTRA_DATA, data);
@@ -341,7 +341,7 @@ public class DecryptFilesFragment extends DecryptFragment {
         switch (requestCode) {
             case REQUEST_CODE_PASSPHRASE: {
                 if (resultCode == Activity.RESULT_OK && data != null) {
-                    mPassphrase = data.getStringExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
+                    mPassphrase = data.getParcelableExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
                     decryptOriginalFilename();
                 }
                 return;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/DecryptFragment.java

@@ -32,6 +32,7 @@ import org.sufficientlysecure.keychain.pgp.KeyRing;
 import org.sufficientlysecure.keychain.provider.KeychainContract;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils;
 import org.sufficientlysecure.keychain.ui.util.KeyFormattingUtils.State;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 public abstract class DecryptFragment extends Fragment {
     private static final int RESULT_CODE_LOOKUP_KEY = 0x00007006;
@@ -57,7 +58,7 @@ public abstract class DecryptFragment extends Fragment {
 
 
     // State
-    protected String mPassphrase;
+    protected Passphrase mPassphrase;
     protected byte[] mNfcDecryptedSessionKey;
 
     @Override
@@ -100,7 +101,7 @@ public abstract class DecryptFragment extends Fragment {
         startActivityForResult(intent, REQUEST_CODE_PASSPHRASE);
     }
 
-    protected void startNfcDecrypt(long subKeyId, String pin, byte[] encryptedSessionKey) {
+    protected void startNfcDecrypt(long subKeyId, Passphrase pin, byte[] encryptedSessionKey) {
         // build PendingIntent for Yubikey NFC operations
         Intent intent = new Intent(getActivity(), NfcActivity.class);
         intent.setAction(NfcActivity.ACTION_DECRYPT_SESSION_KEY);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/DecryptTextFragment.java

@@ -161,7 +161,7 @@ public class DecryptTextFragment extends DecryptFragment {
         // data
         data.putInt(KeychainIntentService.TARGET, IOType.BYTES.ordinal());
         data.putByteArray(KeychainIntentService.DECRYPT_CIPHERTEXT_BYTES, mCiphertext.getBytes());
-        data.putString(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
+        data.putParcelable(KeychainIntentService.DECRYPT_PASSPHRASE, mPassphrase);
         data.putByteArray(KeychainIntentService.DECRYPT_NFC_DECRYPTED_SESSION_KEY, mNfcDecryptedSessionKey);
 
         intent.putExtra(KeychainIntentService.EXTRA_DATA, data);
@@ -247,7 +247,7 @@ public class DecryptTextFragment extends DecryptFragment {
 
             case REQUEST_CODE_PASSPHRASE: {
                 if (resultCode == Activity.RESULT_OK && data != null) {
-                    mPassphrase = data.getStringExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
+                    mPassphrase = data.getParcelableExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
                     decryptStart();
                 } else {
                     getActivity().finish();

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EditKeyFragment.java

@@ -67,6 +67,7 @@ import org.sufficientlysecure.keychain.ui.dialog.EditUserIdDialogFragment;
 import org.sufficientlysecure.keychain.ui.dialog.SetPassphraseDialogFragment;
 import org.sufficientlysecure.keychain.ui.util.Notify;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 public class EditKeyFragment extends LoaderFragment implements
         LoaderManager.LoaderCallbacks<Cursor> {
@@ -100,7 +101,7 @@ public class EditKeyFragment extends LoaderFragment implements
     private SaveKeyringParcel mSaveKeyringParcel;
 
     private String mPrimaryUserId;
-    private String mCurrentPassphrase;
+    private Passphrase mCurrentPassphrase;
 
     /**
      * Creates new instance of this fragment
@@ -267,7 +268,7 @@ public class EditKeyFragment extends LoaderFragment implements
         switch (requestCode) {
             case REQUEST_CODE_PASSPHRASE: {
                 if (resultCode == Activity.RESULT_OK && data != null) {
-                    mCurrentPassphrase = data.getStringExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
+                    mCurrentPassphrase = data.getParcelableExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
                     // Prepare the loaders. Either re-connect with an existing ones,
                     // or start new ones.
                     getLoaderManager().initLoader(LOADER_ID_USER_IDS, null, EditKeyFragment.this);
@@ -386,7 +387,7 @@ public class EditKeyFragment extends LoaderFragment implements
 
                     // cache new returned passphrase!
                     mSaveKeyringParcel.mNewUnlock = new ChangeUnlockParcel(
-                            data.getString(SetPassphraseDialogFragment.MESSAGE_NEW_PASSPHRASE),
+                            (Passphrase) data.getParcelable(SetPassphraseDialogFragment.MESSAGE_NEW_PASSPHRASE),
                             null
                     );
                 }
@@ -593,7 +594,7 @@ public class EditKeyFragment extends LoaderFragment implements
         getActivity().finish();
     }
 
-    private void saveInDatabase(String passphrase) {
+    private void saveInDatabase(Passphrase passphrase) {
         Log.d(Constants.TAG, "mSaveKeyringParcel:\n" + mSaveKeyringParcel.toString());
 
         KeychainIntentServiceHandler saveHandler = new KeychainIntentServiceHandler(
@@ -640,7 +641,7 @@ public class EditKeyFragment extends LoaderFragment implements
 
         // fill values for this action
         Bundle data = new Bundle();
-        data.putString(KeychainIntentService.EDIT_KEYRING_PASSPHRASE, passphrase);
+        data.putParcelable(KeychainIntentService.EDIT_KEYRING_PASSPHRASE, passphrase);
         data.putParcelable(KeychainIntentService.EDIT_KEYRING_PARCEL, mSaveKeyringParcel);
         intent.putExtra(KeychainIntentService.EXTRA_DATA, data);
 

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptActivity.java

@@ -32,6 +32,7 @@ import org.sufficientlysecure.keychain.operations.results.SignEncryptResult;
 import org.sufficientlysecure.keychain.pgp.SignEncryptParcel;
 import org.sufficientlysecure.keychain.service.KeychainIntentService;
 import org.sufficientlysecure.keychain.service.KeychainIntentServiceHandler;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 import java.util.Date;
 
@@ -41,7 +42,7 @@ public abstract class EncryptActivity extends BaseActivity {
     public static final int REQUEST_CODE_NFC = 0x00008002;
 
     // For NFC data
-    protected String mSigningKeyPassphrase = null;
+    protected Passphrase mSigningKeyPassphrase = null;
     protected Date mNfcTimestamp = null;
     protected byte[] mNfcHash = null;
 
@@ -64,7 +65,7 @@ public abstract class EncryptActivity extends BaseActivity {
         startActivityForResult(intent, REQUEST_CODE_PASSPHRASE);
     }
 
-    protected void startNfcSign(long keyId, String pin, byte[] hashToSign, int hashAlgo) {
+    protected void startNfcSign(long keyId, Passphrase pin, byte[] hashToSign, int hashAlgo) {
         // build PendingIntent for Yubikey NFC operations
         Intent intent = new Intent(this, NfcActivity.class);
         intent.setAction(NfcActivity.ACTION_SIGN_HASH);
@@ -84,7 +85,7 @@ public abstract class EncryptActivity extends BaseActivity {
         switch (requestCode) {
             case REQUEST_CODE_PASSPHRASE: {
                 if (resultCode == RESULT_OK && data != null) {
-                    mSigningKeyPassphrase = data.getStringExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
+                    mSigningKeyPassphrase = data.getParcelableExtra(PassphraseDialogActivity.MESSAGE_DATA_PASSPHRASE);
                     startEncrypt();
                     return;
                 }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptActivityInterface.java

@@ -19,6 +19,8 @@ package org.sufficientlysecure.keychain.ui;
 
 import android.net.Uri;
 
+import org.sufficientlysecure.keychain.util.Passphrase;
+
 import java.util.ArrayList;
 
 public interface EncryptActivityInterface {
@@ -39,7 +41,7 @@ public interface EncryptActivityInterface {
     public void setEncryptionKeys(long[] encryptionKeys);
     public void setEncryptionUsers(String[] encryptionUsers);
 
-    public void setPassphrase(String passphrase);
+    public void setPassphrase(Passphrase passphrase);
 
     // ArrayList on purpose as only those are parcelable
     public ArrayList<Uri> getInputUris();

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptFilesActivity.java

@@ -36,6 +36,7 @@ import org.sufficientlysecure.keychain.pgp.SignEncryptParcel;
 import org.sufficientlysecure.keychain.ui.dialog.DeleteFileDialogFragment;
 import org.sufficientlysecure.keychain.ui.util.Notify;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.ShareHelper;
 
 import java.util.ArrayList;
@@ -72,7 +73,7 @@ public class EncryptFilesActivity extends EncryptActivity implements EncryptActi
     private long mEncryptionKeyIds[] = null;
     private String mEncryptionUserIds[] = null;
     private long mSigningKeyId = Constants.key.none;
-    private String mPassphrase = "";
+    private Passphrase mPassphrase = new Passphrase();
 
     private ArrayList<Uri> mInputUris;
     private ArrayList<Uri> mOutputUris;
@@ -136,7 +137,7 @@ public class EncryptFilesActivity extends EncryptActivity implements EncryptActi
     }
 
     @Override
-    public void setPassphrase(String passphrase) {
+    public void setPassphrase(Passphrase passphrase) {
         mPassphrase = passphrase;
     }
 
@@ -243,8 +244,8 @@ public class EncryptFilesActivity extends EncryptActivity implements EncryptActi
 
         if (isModeSymmetric()) {
             Log.d(Constants.TAG, "Symmetric encryption enabled!");
-            String passphrase = mPassphrase;
+            Passphrase passphrase = mPassphrase;
-            if (passphrase.length() == 0) {
+            if (passphrase.isEmpty()) {
                 passphrase = null;
             }
             data.setSymmetricPassphrase(passphrase);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptSymmetricFragment.java

@@ -28,6 +28,7 @@ import android.view.ViewGroup;
 import android.widget.EditText;
 
 import org.sufficientlysecure.keychain.R;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 public class EncryptSymmetricFragment extends Fragment implements EncryptActivityInterface.UpdateListener {
 
@@ -67,8 +68,13 @@ public class EncryptSymmetricFragment extends Fragment implements EncryptActivit
             @Override
             public void afterTextChanged(Editable s) {
                 // update passphrase in EncryptActivity
-                if (mPassphrase.getText().toString().equals(mPassphraseAgain.getText().toString())) {
+                Passphrase p1 = new Passphrase(mPassphrase.getText());
-                    mEncryptInterface.setPassphrase(s.toString());
+                Passphrase p2 = new Passphrase(mPassphraseAgain.getText());
+                boolean passesEquals = (p1.equals(p2));
+                p1.removeFromMemory();
+                p2.removeFromMemory();
+                if (passesEquals) {
+                    mEncryptInterface.setPassphrase(new Passphrase(mPassphrase.getText()));
                 } else {
                     mEncryptInterface.setPassphrase(null);
                 }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/EncryptTextActivity.java

@@ -36,6 +36,7 @@ import org.sufficientlysecure.keychain.pgp.PgpConstants;
 import org.sufficientlysecure.keychain.pgp.SignEncryptParcel;
 import org.sufficientlysecure.keychain.ui.util.Notify;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.ShareHelper;
 
 import java.util.ArrayList;
@@ -70,7 +71,7 @@ public class EncryptTextActivity extends EncryptActivity implements EncryptActiv
     private String mEncryptionUserIds[] = null;
     // TODO Constants.key.none? What's wrong with a null value?
     private long mSigningKeyId = Constants.key.none;
-    private String mPassphrase = "";
+    private Passphrase mPassphrase = new Passphrase();
 
     private ArrayList<Uri> mInputUris;
     private ArrayList<Uri> mOutputUris;
@@ -134,7 +135,8 @@ public class EncryptTextActivity extends EncryptActivity implements EncryptActiv
     }
 
     @Override
-    public void setPassphrase(String passphrase) {
+    public void setPassphrase(Passphrase passphrase) {
+        mPassphrase.removeFromMemory();
         mPassphrase = passphrase;
     }
 
@@ -223,8 +225,8 @@ public class EncryptTextActivity extends EncryptActivity implements EncryptActiv
 
         if (isModeSymmetric()) {
             Log.d(Constants.TAG, "Symmetric encryption enabled!");
-            String passphrase = mPassphrase;
+            Passphrase passphrase = mPassphrase;
-            if (passphrase.length() == 0) {
+            if (passphrase.isEmpty()) {
                 passphrase = null;
             }
             data.setSymmetricPassphrase(passphrase);

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/PassphraseDialogActivity.java

@@ -55,6 +55,7 @@ import org.sufficientlysecure.keychain.provider.ProviderHelper;
 import org.sufficientlysecure.keychain.service.PassphraseCacheService;
 import org.sufficientlysecure.keychain.ui.dialog.CustomAlertDialogBuilder;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 import org.sufficientlysecure.keychain.util.Preferences;
 
 /**
@@ -318,7 +319,7 @@ public class PassphraseDialogActivity extends FragmentActivity {
             positive.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
-                    final String passphrase = mPassphraseEditText.getText().toString();
+                    final Passphrase passphrase = new Passphrase(mPassphraseEditText);
 
                     // Early breakout if we are dealing with a symmetric key
                     if (mSecretRing == null) {
@@ -395,7 +396,7 @@ public class PassphraseDialogActivity extends FragmentActivity {
             });
         }
 
-        private void finishCaching(String passphrase) {
+        private void finishCaching(Passphrase passphrase) {
             // any indication this isn't needed anymore, don't do it.
             if (mIsCancelled || getActivity() == null) {
                 return;

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/SetPassphraseDialogFragment.java

@@ -45,6 +45,7 @@ import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.ui.widget.PassphraseEditText;
 import org.sufficientlysecure.keychain.util.Log;
+import org.sufficientlysecure.keychain.util.Passphrase;
 
 public class SetPassphraseDialogFragment extends DialogFragment implements OnEditorActionListener {
     private static final String ARG_MESSENGER = "messenger";
@@ -67,12 +68,12 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
      * @param messenger to communicate back after setting the passphrase
      * @return
      */
-    public static SetPassphraseDialogFragment newInstance(Messenger messenger, String oldPassphrase, int title) {
+    public static SetPassphraseDialogFragment newInstance(Messenger messenger, Passphrase oldPassphrase, int title) {
         SetPassphraseDialogFragment frag = new SetPassphraseDialogFragment();
         Bundle args = new Bundle();
         args.putInt(ARG_TITLE, title);
         args.putParcelable(ARG_MESSENGER, messenger);
-        args.putString(ARG_OLD_PASSPHRASE, oldPassphrase);
+        args.putParcelable(ARG_OLD_PASSPHRASE, oldPassphrase);
 
         frag.setArguments(args);
 
@@ -88,7 +89,7 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
 
         int title = getArguments().getInt(ARG_TITLE);
         mMessenger = getArguments().getParcelable(ARG_MESSENGER);
-        String oldPassphrase = getArguments().getString(ARG_OLD_PASSPHRASE);
+        Passphrase oldPassphrase = getArguments().getParcelable(ARG_OLD_PASSPHRASE);
 
         CustomAlertDialogBuilder alert = new CustomAlertDialogBuilder(activity);
 
@@ -103,7 +104,7 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
         mNoPassphraseCheckBox = (CheckBox) view.findViewById(R.id.passphrase_no_passphrase);
 
 
-        if (TextUtils.isEmpty(oldPassphrase)) {
+        if (oldPassphrase.isEmpty()) {
             mNoPassphraseCheckBox.setChecked(true);
             mPassphraseEditText.setEnabled(false);
             mPassphraseAgainEditText.setEnabled(false);
@@ -123,12 +124,12 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
             public void onClick(DialogInterface dialog, int id) {
                 dismiss();
 
-                String passphrase1;
+                Passphrase passphrase1 = new Passphrase();
                 if (mNoPassphraseCheckBox.isChecked()) {
-                    passphrase1 = "";
+                    passphrase1.setEmpty();
                 } else {
-                    passphrase1 = mPassphraseEditText.getText().toString();
+                    passphrase1 = new Passphrase(mPassphraseEditText);
-                    String passphrase2 = mPassphraseAgainEditText.getText().toString();
+                    Passphrase passphrase2 = new Passphrase(mPassphraseAgainEditText);
                     if (!passphrase1.equals(passphrase2)) {
                         Toast.makeText(
                                 activity,
@@ -139,7 +140,7 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
                         return;
                     }
 
-                    if (passphrase1.equals("")) {
+                    if (passphrase1.isEmpty()) {
                         Toast.makeText(
                                 activity,
                                 getString(R.string.error_message,
@@ -152,7 +153,7 @@ public class SetPassphraseDialogFragment extends DialogFragment implements OnEdi
 
                 // return resulting data back to activity
                 Bundle data = new Bundle();
-                data.putString(MESSAGE_NEW_PASSPHRASE, passphrase1);
+                data.putParcelable(MESSAGE_NEW_PASSPHRASE, passphrase1);
 
                 sendMessageToHandler(MESSAGE_OKAY, data);
             }

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/Passphrase.java

@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2015 Dominik Schürmann <dominik@dominikschuermann.de>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.sufficientlysecure.keychain.util;
+
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.text.Editable;
+import android.widget.EditText;
+
+import org.sufficientlysecure.keychain.Constants;
+
+import java.util.Arrays;
+
+public class Passphrase implements Parcelable {
+    private char[] mPassphrase;
+
+    /**
+     * According to http://stackoverflow.com/a/15844273 EditText is not using String internally
+     * but char[]. Thus, we can get the char[] directly from it.
+     */
+    public Passphrase(Editable editable) {
+        int pl = editable.length();
+        mPassphrase = new char[pl];
+        editable.getChars(0, pl, mPassphrase, 0);
+        // TODO: clean up internal char[] of EditText after getting the passphrase?
+//        editText.getText().replace()
+        System.gc();
+    }
+
+    public Passphrase(EditText editText) {
+        this(editText.getText());
+    }
+
+    public Passphrase(String passphrase) {
+        mPassphrase = passphrase.toCharArray();
+    }
+
+    public Passphrase() {
+        setEmpty();
+    }
+
+    public char[] getCharArray() {
+        return mPassphrase;
+    }
+
+    public boolean isEmpty() {
+        return (mPassphrase.length == 0);
+    }
+
+    public void setEmpty() {
+        removeFromMemory();
+        mPassphrase = new char[0];
+    }
+
+    public void removeFromMemory() {
+        if (mPassphrase != null) {
+            Arrays.fill(mPassphrase, ' ');
+            System.gc();
+        }
+    }
+
+    @Override
+    public String toString() {
+        if (Constants.DEBUG) {
+            return "Passphrase{" +
+                    "mPassphrase=" + Arrays.toString(mPassphrase) +
+                    '}';
+        } else {
+            return "Passphrase: hidden";
+        }
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+
+        Passphrase that = (Passphrase) o;
+        if (!Arrays.equals(mPassphrase, that.mPassphrase)) {
+            return false;
+        }
+
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        return mPassphrase != null ? Arrays.hashCode(mPassphrase) : 0;
+    }
+
+    private Passphrase(Parcel source) {
+        mPassphrase = source.createCharArray();
+    }
+
+    public void writeToParcel(Parcel dest, int flags) {
+        dest.writeCharArray(mPassphrase);
+    }
+
+    public static final Creator<Passphrase> CREATOR = new Creator<Passphrase>() {
+        public Passphrase createFromParcel(final Parcel source) {
+            return new Passphrase(source);
+        }
+
+        public Passphrase[] newArray(final int size) {
+            return new Passphrase[size];
+        }
+    };
+
+    public int describeContents() {
+        return 0;
+    }
+}