am 38dc1542: Merge "Always mix in additional entropy into keymaster." into mnc-dev (f5158eb2) · Commits · e / os / android_frameworks_base

keystore/java/android/security/KeyStoreCipherSpi.java

+3 −4

Original line number	Diff line number	Diff line
		@@ -634,10 +634,9 @@ public abstract class KeyStoreCipherSpi extends CipherSpi implements KeyStoreCry
		if ((mIv == null) && (mEncrypting)) {
		// IV was not provided by the caller and thus will be generated by keymaster.
		// Mix in some additional entropy from the provided SecureRandom.
		if (mRng != null) {
		mAdditionalEntropyForBegin = new byte[mBlockSizeBytes];
		mRng.nextBytes(mAdditionalEntropyForBegin);
		}
		mAdditionalEntropyForBegin =
		KeyStoreCryptoOperationUtils.getRandomBytesToMixIntoKeystoreRng(
		mRng, mBlockSizeBytes);
		}
		}
		}

+28 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@ import android.security.keymaster.KeymasterDefs;
		import java.security.GeneralSecurityException;
		import java.security.InvalidAlgorithmParameterException;
		import java.security.InvalidKeyException;
		import java.security.SecureRandom;

		/**
		* Assorted utility methods for implementing crypto operations on top of KeyStore.
		@@ -28,6 +29,9 @@ import java.security.InvalidKeyException;
		* @hide
		*/
		abstract class KeyStoreCryptoOperationUtils {

		private static volatile SecureRandom sRng;

		private KeyStoreCryptoOperationUtils() {}

		/**
		@@ -81,4 +85,28 @@ abstract class KeyStoreCryptoOperationUtils {
		// General cases
		return getInvalidKeyExceptionForInit(keyStore, key, beginOpResultCode);
		}

		/**
		* Returns the requested number of random bytes to mix into keystore/keymaster RNG.
		*
		* @param rng RNG from which to obtain the random bytes or {@code null} for the platform-default
		* RNG.
		*/
		static byte[] getRandomBytesToMixIntoKeystoreRng(SecureRandom rng, int sizeBytes) {
		if (rng == null) {
		rng = getRng();
		}
		byte[] result = new byte[sizeBytes];
		rng.nextBytes(result);
		return result;
		}

		private static SecureRandom getRng() {
		// IMPLEMENTATION NOTE: It's OK to share a SecureRandom instance because SecureRandom is
		// required to be thread-safe.
		if (sRng == null) {
		sRng = new SecureRandom();
		}
		return sRng;
		}
		}

+3 −6

Original line number	Diff line number	Diff line
		@@ -173,12 +173,9 @@ public abstract class KeyStoreKeyGeneratorSpi extends KeyGeneratorSpi {
		args.addBoolean(KeymasterDefs.KM_TAG_CALLER_NONCE);
		}

		byte[] additionalEntropy = null;
		SecureRandom rng = mRng;
		if (rng != null) {
		additionalEntropy = new byte[(keySizeBits + 7) / 8];
		rng.nextBytes(additionalEntropy);
		}
		byte[] additionalEntropy =
		KeyStoreCryptoOperationUtils.getRandomBytesToMixIntoKeystoreRng(
		mRng, (keySizeBits + 7) / 8);

		int flags = spec.getFlags();
		String keyAliasInKeystore = Credentials.USER_SECRET_KEY + spec.getKeystoreAlias();