Extracted CRAM-MD5 computation into separate class.

This gets rid of duplicated code in ImapStore, Pop3Store, and
SmtpTransport.

src/com/fsck/k9/mail/Authentication.java

@@ -0,0 +1,85 @@
+package com.fsck.k9.mail;
+
+import java.security.MessageDigest;
+
+import com.fsck.k9.mail.filter.Base64;
+import com.fsck.k9.mail.filter.Hex;
+
+public class Authentication {
+	private static final String US_ASCII = "US-ASCII";
+
+	/**
+	 * Computes the response for CRAM-MD5 authentication mechanism given the user credentials and
+	 * the server-provided nonce.
+	 *
+	 * @param username The username.
+	 * @param password The password.
+	 * @param b64Nonce The nonce as base64-encoded string.
+	 * @return The CRAM-MD5 response.
+	 *
+	 * @throws AuthenticationFailedException If something went wrong.
+	 *
+	 * @see Authentication#computeCramMd5Bytes(String, String, byte[])
+	 */
+	public static String computeCramMd5(String username, String password, String b64Nonce)
+	throws AuthenticationFailedException {
+
+        try {
+        	byte[] b64NonceBytes = b64Nonce.getBytes(US_ASCII);
+			byte[] b64CRAM = computeCramMd5Bytes(username, password, b64NonceBytes);
+		    return new String(b64CRAM, US_ASCII);
+        } catch (AuthenticationFailedException e) {
+        	throw e;
+        } catch (Exception e) {
+        	throw new AuthenticationFailedException("This shouldn't happen", e);
+        }
+	}
+
+	/**
+	 * Computes the response for CRAM-MD5 authentication mechanism given the user credentials and
+	 * the server-provided nonce.
+	 *
+	 * @param username The username.
+	 * @param password The password.
+	 * @param b64Nonce The nonce as base64-encoded byte array.
+	 * @return The CRAM-MD5 response as byte array.
+	 *
+	 * @throws AuthenticationFailedException If something went wrong.
+	 *
+	 * @see <a href="https://tools.ietf.org/html/rfc2195">RFC 2195</a>
+	 */
+	public static byte[] computeCramMd5Bytes(String username, String password, byte[] b64Nonce)
+	throws AuthenticationFailedException {
+
+        try {
+			byte[] nonce = Base64.decodeBase64(b64Nonce);
+
+		    byte[] secretBytes = password.getBytes(US_ASCII);
+		    MessageDigest md = MessageDigest.getInstance("MD5");
+		    if (secretBytes.length > 64) {
+		        secretBytes = md.digest(secretBytes);
+		    }
+
+			byte[] ipad = new byte[64];
+		    byte[] opad = new byte[64];
+		    System.arraycopy(secretBytes, 0, ipad, 0, secretBytes.length);
+		    System.arraycopy(secretBytes, 0, opad, 0, secretBytes.length);
+		    for (int i = 0; i < ipad.length; i++) ipad[i] ^= 0x36;
+		    for (int i = 0; i < opad.length; i++) opad[i] ^= 0x5c;
+
+		    md.update(ipad);
+		    byte[] firstPass = md.digest(nonce);
+
+		    md.update(opad);
+		    byte[] result = md.digest(firstPass);
+
+		    String plainCRAM = username + " " + new String(Hex.encodeHex(result));
+		    byte[] b64CRAM = Base64.encodeBase64(plainCRAM.getBytes(US_ASCII));
+
+		    return b64CRAM;
+
+        } catch (Exception e) {
+        	throw new AuthenticationFailedException("Something went wrong during CRAM-MD5 computation", e);
+        }
+	}
+}

src/com/fsck/k9/mail/store/ImapStore.java

@@ -20,8 +20,6 @@ import java.nio.ByteBuffer;
 import java.nio.CharBuffer;
 import java.nio.charset.Charset;
 import java.security.GeneralSecurityException;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.security.Security;
 import java.text.SimpleDateFormat;
@@ -61,6 +59,7 @@ import com.fsck.k9.controller.MessageRetrievalListener;
 import com.fsck.k9.helper.Utility;
 import com.fsck.k9.helper.power.TracingPowerManager;
 import com.fsck.k9.helper.power.TracingPowerManager.TracingWakeLock;
+import com.fsck.k9.mail.Authentication;
 import com.fsck.k9.mail.AuthenticationFailedException;
 import com.fsck.k9.mail.Body;
 import com.fsck.k9.mail.CertificateValidationException;
@@ -73,10 +72,8 @@ import com.fsck.k9.mail.Part;
 import com.fsck.k9.mail.PushReceiver;
 import com.fsck.k9.mail.Pusher;
 import com.fsck.k9.mail.Store;
-import com.fsck.k9.mail.filter.Base64;
 import com.fsck.k9.mail.filter.EOLConvertingOutputStream;
 import com.fsck.k9.mail.filter.FixedLengthInputStream;
-import com.fsck.k9.mail.filter.Hex;
 import com.fsck.k9.mail.filter.PeekableInputStream;
 import com.fsck.k9.mail.internet.MimeBodyPart;
 import com.fsck.k9.mail.internet.MimeHeader;
@@ -2099,38 +2096,14 @@ public class ImapStore extends Store {
                 }
                 byte[] b64NonceTrim = new byte[b64NonceLen - 2];
                 System.arraycopy(buf, 1, b64NonceTrim, 0, b64NonceLen - 2);
-                byte[] nonce = Base64.decodeBase64(b64NonceTrim);
-                if (K9.DEBUG) {
-                    Log.d(K9.LOG_TAG, "Got nonce: " + new String(b64NonceTrim, "US-ASCII"));
-                    Log.d(K9.LOG_TAG, "Plaintext nonce: " + new String(nonce, "US-ASCII"));
-                }
 
-                byte[] ipad = new byte[64];
+                byte[] b64CRAM = Authentication.computeCramMd5Bytes(mSettings.getUsername(),
-                byte[] opad = new byte[64];
+                		mSettings.getPassword(), b64NonceTrim);
-                byte[] secretBytes = mSettings.getPassword().getBytes("US-ASCII");
-                MessageDigest md = MessageDigest.getInstance("MD5");
-                if (secretBytes.length > 64) {
-                    secretBytes = md.digest(secretBytes);
-                }
-                System.arraycopy(secretBytes, 0, ipad, 0, secretBytes.length);
-                System.arraycopy(secretBytes, 0, opad, 0, secretBytes.length);
-                for (int i = 0; i < ipad.length; i++) ipad[i] ^= 0x36;
-                for (int i = 0; i < opad.length; i++) opad[i] ^= 0x5c;
-                md.update(ipad);
-                byte[] firstPass = md.digest(nonce);
-                md.update(opad);
-                byte[] result = md.digest(firstPass);
-                String plainCRAM = mSettings.getUsername() + " " + new String(Hex.encodeHex(result));
-                byte[] b64CRAM = Base64.encodeBase64(plainCRAM.getBytes("US-ASCII"));
-                if (K9.DEBUG) {
-                    Log.d(K9.LOG_TAG, "Username == " + mSettings.getUsername());
-                    Log.d(K9.LOG_TAG, "plainCRAM: " + plainCRAM);
-                    Log.d(K9.LOG_TAG, "b64CRAM: " + new String(b64CRAM, "US-ASCII"));
-                }
 
                 mOut.write(b64CRAM);
                 mOut.write(new byte[] { 0x0d, 0x0a });
                 mOut.flush();
+
                 int respLen = 0;
                 for (int i = 0; i < buf.length; i++) {
                     buf[i] = (byte)mIn.read();
@@ -2139,15 +2112,14 @@ public class ImapStore extends Store {
                         break;
                     }
                 }
+
                 String toMatch = tag + " OK";
                 String respStr = new String(buf, 0, respLen);
                 if (!respStr.startsWith(toMatch)) {
                     throw new AuthenticationFailedException("CRAM-MD5 error: " + respStr);
                 }
             } catch (IOException ioe) {
-                throw new AuthenticationFailedException("CRAM-MD5 Auth Failed.");
+                throw new AuthenticationFailedException("CRAM-MD5 Auth Failed.", ioe);
-            } catch (NoSuchAlgorithmException nsae) {
-                throw new AuthenticationFailedException("MD5 Not Available.");
             }
         }
 

src/com/fsck/k9/mail/store/Pop3Store.java

@@ -9,8 +9,6 @@ import com.fsck.k9.controller.MessageRetrievalListener;
 import com.fsck.k9.helper.Utility;
 import com.fsck.k9.mail.*;
 import com.fsck.k9.mail.Folder.OpenMode;
-import com.fsck.k9.mail.filter.Base64;
-import com.fsck.k9.mail.filter.Hex;
 import com.fsck.k9.mail.internet.MimeMessage;
 
 import javax.net.ssl.SSLContext;
@@ -19,8 +17,6 @@ import javax.net.ssl.TrustManager;
 import java.io.*;
 import java.net.*;
 import java.security.GeneralSecurityException;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Date;
@@ -231,40 +227,9 @@ public class Pop3Store extends Store {
                 if (useCramMd5)
                 {
                     try {
-                        String nonce64, plainCRAM, b64CRAM;
+                        String b64Nonce = executeSimpleCommand("AUTH CRAM-MD5").replace("+ ", "");
-                        MessageDigest md;
-                        byte[] ipad = new byte[64];
-                        byte[] opad = new byte[64];
-                        byte[] nonce, secretBytes, firstPass, result;
-
-                        nonce64 = executeSimpleCommand("AUTH CRAM-MD5").replace("+ ", "");
-                        nonce = Base64.decodeBase64(nonce64.getBytes("US-ASCII"));
-
-                        secretBytes = mPassword.getBytes("US-ASCII");
-                        try {
-                            md = MessageDigest.getInstance("MD5");
-                        } catch (NoSuchAlgorithmException nsae) {
-                            throw new AuthenticationFailedException("MD5 Not Available.");
-                        }
-
-                        if (secretBytes.length > 64) {
-                            secretBytes = md.digest(secretBytes);
-                        }
-
-                        System.arraycopy(secretBytes, 0, ipad, 0, secretBytes.length);
-                        System.arraycopy(secretBytes, 0, opad, 0, secretBytes.length);
-                        for (int i = 0; i < ipad.length; i++) ipad[i] ^= 0x36;
-                        for (int i = 0; i < opad.length; i++) opad[i] ^= 0x5c;
-
-                        md.update(ipad);
-                        firstPass = md.digest(nonce);
-
-                        md.update(opad);
-                        result = md.digest(firstPass);
-
-                        plainCRAM = mUsername + " " + new String(Hex.encodeHex(result));
-                        b64CRAM = new String(Base64.encodeBase64(plainCRAM.getBytes("US-ASCII")), "US-ASCII");
 
+                        String b64CRAM = Authentication.computeCramMd5(mUsername, mPassword, b64Nonce);
                         executeSimpleCommand(b64CRAM);
 
                     } catch (MessagingException me) {

src/com/fsck/k9/mail/transport/SmtpTransport.java

@@ -7,7 +7,6 @@ import com.fsck.k9.mail.*;
 import com.fsck.k9.mail.Message.RecipientType;
 import com.fsck.k9.mail.filter.Base64;
 import com.fsck.k9.mail.filter.EOLConvertingOutputStream;
-import com.fsck.k9.mail.filter.Hex;
 import com.fsck.k9.mail.filter.LineWrapOutputStream;
 import com.fsck.k9.mail.filter.PeekableInputStream;
 import com.fsck.k9.mail.filter.SmtpDataStuffing;
@@ -25,8 +24,6 @@ import java.io.OutputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.*;
 import java.security.GeneralSecurityException;
-import java.security.MessageDigest;
-import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
 
 import java.util.*;
@@ -522,33 +519,15 @@ public class SmtpTransport extends Transport {
 
     private void saslAuthCramMD5(String username, String password) throws MessagingException,
         AuthenticationFailedException, IOException {
+
     	List<String> respList = executeSimpleCommand("AUTH CRAM-MD5");
-        if (respList.size() != 1) throw new AuthenticationFailedException("Unable to negotiate CRAM-MD5");
+        if (respList.size() != 1) {
+        	throw new AuthenticationFailedException("Unable to negotiate CRAM-MD5");
+        }
+
         String b64Nonce = respList.get(0);
-        byte[] nonce = Base64.decodeBase64(b64Nonce.getBytes("US-ASCII"));
+        String b64CRAMString = Authentication.computeCramMd5(mUsername, mPassword, b64Nonce);
-        byte[] ipad = new byte[64];
+
-        byte[] opad = new byte[64];
-        byte[] secretBytes = password.getBytes("US-ASCII");
-        MessageDigest md;
-        try {
-            md = MessageDigest.getInstance("MD5");
-        } catch (NoSuchAlgorithmException nsae) {
-            throw new AuthenticationFailedException("MD5 Not Available.");
-        }
-        if (secretBytes.length > 64) {
-            secretBytes = md.digest(secretBytes);
-        }
-        System.arraycopy(secretBytes, 0, ipad, 0, secretBytes.length);
-        System.arraycopy(secretBytes, 0, opad, 0, secretBytes.length);
-        for (int i = 0; i < ipad.length; i++) ipad[i] ^= 0x36;
-        for (int i = 0; i < opad.length; i++) opad[i] ^= 0x5c;
-        md.update(ipad);
-        byte[] firstPass = md.digest(nonce);
-        md.update(opad);
-        byte[] result = md.digest(firstPass);
-        String plainCRAM = username + " " + new String(Hex.encodeHex(result));
-        byte[] b64CRAM = Base64.encodeBase64(plainCRAM.getBytes("US-ASCII"));
-        String b64CRAMString = new String(b64CRAM, "US-ASCII");
         try {
             executeSimpleCommand(b64CRAMString, true);
         } catch (MessagingException me) {