RSA encrypt with private key in Android Keystore. (5552c89f) · Commits · e / os / android_frameworks_base

keystore/java/android/security/keystore/AndroidKeyStoreCipherSpiBase.java

+24 −4

Original line number	Diff line number	Diff line
		@@ -56,6 +56,7 @@ abstract class AndroidKeyStoreCipherSpiBase extends CipherSpi implements KeyStor
		// Fields below are populated by Cipher.init and KeyStore.begin and should be preserved after
		// doFinal finishes.
		private boolean mEncrypting;
		private int mKeymasterPurposeOverride = -1;
		private AndroidKeyStoreKey mKey;
		private SecureRandom mRng;

		@@ -165,6 +166,7 @@ abstract class AndroidKeyStoreCipherSpiBase extends CipherSpi implements KeyStor
		mKeyStore.abort(operationToken);
		}
		mEncrypting = false;
		mKeymasterPurposeOverride = -1;
		mKey = null;
		mRng = null;
		mOperationToken = null;
		@@ -210,9 +212,16 @@ abstract class AndroidKeyStoreCipherSpiBase extends CipherSpi implements KeyStor
		byte[] additionalEntropy = KeyStoreCryptoOperationUtils.getRandomBytesToMixIntoKeystoreRng(
		mRng, getAdditionalEntropyAmountForBegin());

		int purpose;
		if (mKeymasterPurposeOverride != -1) {
		purpose = mKeymasterPurposeOverride;
		} else {
		purpose = mEncrypting
		? KeymasterDefs.KM_PURPOSE_ENCRYPT : KeymasterDefs.KM_PURPOSE_DECRYPT;
		}
		OperationResult opResult = mKeyStore.begin(
		mKey.getAlias(),
		mEncrypting ? KeymasterDefs.KM_PURPOSE_ENCRYPT : KeymasterDefs.KM_PURPOSE_DECRYPT,
		purpose,
		true, // permit aborting this operation if keystore runs out of resources
		keymasterInputArgs,
		additionalEntropy);
		@@ -346,11 +355,11 @@ abstract class AndroidKeyStoreCipherSpiBase extends CipherSpi implements KeyStor
		} catch (KeyStoreException e) {
		switch (e.getErrorCode()) {
		case KeymasterDefs.KM_ERROR_INVALID_INPUT_LENGTH:
		throw new IllegalBlockSizeException();
		throw (IllegalBlockSizeException) new IllegalBlockSizeException().initCause(e);
		case KeymasterDefs.KM_ERROR_INVALID_ARGUMENT:
		throw new BadPaddingException();
		throw (BadPaddingException) new BadPaddingException().initCause(e);
		case KeymasterDefs.KM_ERROR_VERIFICATION_FAILED:
		throw new AEADBadTagException();
		throw (AEADBadTagException) new AEADBadTagException().initCause(e);
		default:
		throw (IllegalBlockSizeException) new IllegalBlockSizeException().initCause(e);
		}
		@@ -436,6 +445,17 @@ abstract class AndroidKeyStoreCipherSpiBase extends CipherSpi implements KeyStor
		mKey = key;
		}

		/**
		* Overrides the default purpose/type of the crypto operation.
		*/
		protected final void setKeymasterPurposeOverride(int keymasterPurpose) {
		mKeymasterPurposeOverride = keymasterPurpose;
		}

		protected final int getKeymasterPurposeOverride() {
		return mKeymasterPurposeOverride;
		}

		/**
		* Returns {@code true} if this cipher is initialized for encryption, {@code false} if this
		* cipher is initialized for decryption.

keystore/java/android/security/keystore/AndroidKeyStoreRSACipherSpi.java

+61 −8

Original line number	Diff line number	Diff line
		@@ -59,6 +59,13 @@ abstract class AndroidKeyStoreRSACipherSpi extends AndroidKeyStoreCipherSpiBase
		super(KeymasterDefs.KM_PAD_NONE);
		}

		@Override
		protected boolean isEncryptingUsingPrivateKeyPermitted() {
		// RSA encryption with no padding using private key is is a way to implement raw RSA
		// signatures. We have to support this.
		return true;
		}

		@Override
		protected void initAlgorithmSpecificParameters() throws InvalidKeyException {}

		@@ -152,8 +159,11 @@ abstract class AndroidKeyStoreRSACipherSpi extends AndroidKeyStoreCipherSpiBase
		paddedInput.length - bufferedInput.length,
		bufferedInput.length);
		} else {
		// No need to pad input
		paddedInput = bufferedInput;
		// RI throws BadPaddingException in this scenario. INVALID_ARGUMENT below will
		// be translated into BadPaddingException.
		throw new KeyStoreException(KeymasterDefs.KM_ERROR_INVALID_ARGUMENT,
		"Message size (" + bufferedInput.length + " bytes) must be smaller than"
		+ " modulus (" + mModulusSizeBytes + " bytes)");
		}
		return mDelegate.doFinal(paddedInput, 0, paddedInput.length);
		}
		@@ -412,14 +422,46 @@ abstract class AndroidKeyStoreRSACipherSpi extends AndroidKeyStoreCipherSpiBase
		}

		if (keystoreKey instanceof PrivateKey) {
		if ((opmode != Cipher.DECRYPT_MODE) && (opmode != Cipher.UNWRAP_MODE)) {
		throw new InvalidKeyException("Private key cannot be used with opmode: " + opmode
		+ ". Only DECRYPT_MODE and UNWRAP_MODE supported");
		// Private key
		switch (opmode) {
		case Cipher.DECRYPT_MODE:
		case Cipher.UNWRAP_MODE:
		// Permitted
		break;
		case Cipher.ENCRYPT_MODE:
		if (!isEncryptingUsingPrivateKeyPermitted()) {
		throw new InvalidKeyException(
		"RSA private keys cannot be used with Cipher.ENCRYPT_MODE"
		+ ". Only RSA public keys supported for this mode");
		}
		// JCA doesn't provide a way to generate raw RSA signatures (with arbitrary
		// padding). Thus, encrypting with private key is used instead.
		setKeymasterPurposeOverride(KeymasterDefs.KM_PURPOSE_SIGN);
		break;
		case Cipher.WRAP_MODE:
		throw new InvalidKeyException(
		"RSA private keys cannot be used with Cipher.WRAP_MODE"
		+ ". Only RSA public keys supported for this mode");
		// break;
		default:
		throw new InvalidKeyException(
		"RSA private keys cannot be used with opmode: " + opmode);
		}
		} else {
		if ((opmode != Cipher.ENCRYPT_MODE) && (opmode != Cipher.WRAP_MODE)) {
		throw new InvalidKeyException("Public key cannot be used with opmode: " + opmode
		+ ". Only ENCRYPT_MODE and WRAP_MODE supported");
		// Public key
		switch (opmode) {
		case Cipher.ENCRYPT_MODE:
		case Cipher.WRAP_MODE:
		// Permitted
		return;
		case Cipher.DECRYPT_MODE:
		case Cipher.UNWRAP_MODE:
		throw new InvalidKeyException("RSA public keys cannot be used with opmode: "
		+ opmode + ". Only RSA private keys supported for this opmode.");
		// break;
		default:
		throw new InvalidKeyException(
		"RSA public keys cannot be used with opmode: " + opmode);
		}
		}

		@@ -438,6 +480,10 @@ abstract class AndroidKeyStoreRSACipherSpi extends AndroidKeyStoreCipherSpiBase
		setKey(keystoreKey);
		}

		protected boolean isEncryptingUsingPrivateKeyPermitted() {
		return false;
		}

		@Override
		protected final void resetAll() {
		mModulusSizeBytes = -1;
		@@ -454,6 +500,13 @@ abstract class AndroidKeyStoreRSACipherSpi extends AndroidKeyStoreCipherSpiBase
		@NonNull KeymasterArguments keymasterArgs) {
		keymasterArgs.addInt(KeymasterDefs.KM_TAG_ALGORITHM, KeymasterDefs.KM_ALGORITHM_RSA);
		keymasterArgs.addInt(KeymasterDefs.KM_TAG_PADDING, mKeymasterPadding);
		int purposeOverride = getKeymasterPurposeOverride();
		if ((purposeOverride != -1)
		&& ((purposeOverride == KeymasterDefs.KM_PURPOSE_SIGN)
		\|\| (purposeOverride == KeymasterDefs.KM_PURPOSE_VERIFY))) {
		// Keymaster sign/verify requires digest to be specified. For raw sign/verify it's NONE.
		keymasterArgs.addInt(KeymasterDefs.KM_TAG_DIGEST, KeymasterDefs.KM_DIGEST_NONE);
		}
		}

		@Override