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https://github.com/moparisthebest/open-keychain
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Do not seed /dev/urandom. urandom is non-writeable on some devices. Because only OpenSSL seeding is broken, this should not result in security problems!
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c90e776055
commit
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@ -18,9 +18,7 @@ import java.io.DataInputStream;
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import java.io.DataOutputStream;
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import java.io.File;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.io.UnsupportedEncodingException;
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import java.security.NoSuchAlgorithmException;
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import java.security.Provider;
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@ -35,6 +33,19 @@ import java.security.Security;
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* Architecture primitives. A good place to invoke them is in the application's {@code onCreate}.
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*
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* copied from http://android-developers.blogspot.de/2013/08/some-securerandom-thoughts.html
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*
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*
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* Sep 15, 2013:
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* On some devices /dev/urandom is non-writable!
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* No need to seed /dev/urandom. urandom should have enough seeds from the OS and kernel.
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* Only OpenSSL seeds are broken. See http://emboss.github.io/blog/2013/08/21/openssl-prng-is-not-really-fork-safe
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*
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* see also:
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* https://github.com/k9mail/k-9/commit/dda8f64276d4d29c43f86237cd77819c28f22f21
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* In addition to a couple of custom ROMs linking /dev/urandom to a non-writable
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* random version, now Samsung's SELinux policy also prevents apps from opening
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* /dev/urandom for writing. Since we shouldn't need to write to /dev/urandom anyway
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* we now simply don't.
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*/
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public final class PRNGFixes {
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@ -138,6 +149,7 @@ public final class PRNGFixes {
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* {@code Provider} of {@code SecureRandom} engines which pass through all requests to the Linux
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* PRNG.
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*/
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@SuppressWarnings("serial")
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private static class LinuxPRNGSecureRandomProvider extends Provider {
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public LinuxPRNGSecureRandomProvider() {
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@ -155,6 +167,7 @@ public final class PRNGFixes {
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/**
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* {@link SecureRandomSpi} which passes all requests to the Linux PRNG ({@code /dev/urandom}).
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*/
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@SuppressWarnings("serial")
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public static class LinuxPRNGSecureRandom extends SecureRandomSpi {
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/*
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@ -178,40 +191,40 @@ public final class PRNGFixes {
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*/
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private static DataInputStream sUrandomIn;
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/**
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* Output stream for writing to Linux PRNG or {@code null} if not yet opened.
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*
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* @GuardedBy("sLock")
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*/
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private static OutputStream sUrandomOut;
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/**
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* Whether this engine instance has been seeded. This is needed because each instance needs
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* to seed itself if the client does not explicitly seed it.
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*/
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private boolean mSeeded;
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// /**
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// * Output stream for writing to Linux PRNG or {@code null} if not yet opened.
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// *
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// * @GuardedBy("sLock")
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// */
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// private static OutputStream sUrandomOut;
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//
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// /**
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// * Whether this engine instance has been seeded. This is needed because each instance needs
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// * to seed itself if the client does not explicitly seed it.
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// */
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// private boolean mSeeded;
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@Override
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protected void engineSetSeed(byte[] bytes) {
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try {
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OutputStream out;
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synchronized (sLock) {
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out = getUrandomOutputStream();
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}
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out.write(bytes);
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out.flush();
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mSeeded = true;
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} catch (IOException e) {
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throw new SecurityException("Failed to mix seed into " + URANDOM_FILE, e);
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}
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// try {
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// OutputStream out;
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// synchronized (sLock) {
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// out = getUrandomOutputStream();
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// }
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// out.write(bytes);
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// out.flush();
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// mSeeded = true;
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// } catch (IOException e) {
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// throw new SecurityException("Failed to mix seed into " + URANDOM_FILE, e);
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// }
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}
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@Override
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protected void engineNextBytes(byte[] bytes) {
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if (!mSeeded) {
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// Mix in the device- and invocation-specific seed.
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engineSetSeed(generateSeed());
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}
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// if (!mSeeded) {
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// // Mix in the device- and invocation-specific seed.
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// engineSetSeed(generateSeed());
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// }
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try {
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DataInputStream in;
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@ -251,19 +264,19 @@ public final class PRNGFixes {
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}
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}
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private OutputStream getUrandomOutputStream() {
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synchronized (sLock) {
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if (sUrandomOut == null) {
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try {
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sUrandomOut = new FileOutputStream(URANDOM_FILE);
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} catch (IOException e) {
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throw new SecurityException("Failed to open " + URANDOM_FILE
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+ " for writing", e);
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}
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}
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return sUrandomOut;
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}
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}
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// private OutputStream getUrandomOutputStream() {
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// synchronized (sLock) {
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// if (sUrandomOut == null) {
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// try {
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// sUrandomOut = new FileOutputStream(URANDOM_FILE);
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// } catch (IOException e) {
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// throw new SecurityException("Failed to open " + URANDOM_FILE
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// + " for writing", e);
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// }
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// }
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// return sUrandomOut;
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// }
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// }
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}
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/**
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