Erase keys after using them. (Copies created by ciphers, etc, may

still exist.)

api/net/sf/briar/api/crypto/ErasableKey.java

@@ -4,6 +4,9 @@ import javax.crypto.SecretKey;
 
 public interface ErasableKey extends SecretKey {
 
+	/** Returns a copy of the key. */
+	ErasableKey copy();
+
 	/** Erases the key from memory. */
 	void erase();
 }

components/net/sf/briar/crypto/ErasableKeyImpl.java

@@ -33,6 +33,10 @@ class ErasableKeyImpl implements ErasableKey {
 		return "RAW";
 	}
 
+	public ErasableKey copy() {
+		return new ErasableKeyImpl(getEncoded(), algorithm);
+	}
+
 	public void erase() {
 		if(erased) throw new IllegalStateException();
 		ByteUtils.erase(key);

components/net/sf/briar/transport/ConnectionDecrypterImpl.java

@@ -43,6 +43,7 @@ implements ConnectionDecrypter {
 	}
 
 	public void readMac(byte[] mac) throws IOException {
+		try {
 			if(betweenFrames) throw new IllegalStateException();
 			// If we have any plaintext in the buffer, copy it into the MAC
 			System.arraycopy(buf, bufOff, mac, 0, bufLen);
@@ -68,13 +69,21 @@ implements ConnectionDecrypter {
 			}
 			bufOff = bufLen = 0;
 			betweenFrames = true;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	@Override
 	public int read() throws IOException {
+		try {
 			if(betweenFrames) initialiseCipher();
 			if(bufLen == 0) {
-			if(!readBlock()) return -1;
+				if(!readBlock()) {
+					frameKey.erase();
+					return -1;
+				}
 				bufOff = 0;
 				bufLen = buf.length;
 			}
@@ -82,6 +91,10 @@ implements ConnectionDecrypter {
 			bufOff++;
 			bufLen--;
 			return i < 0 ? i + 256 : i;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	@Override
@@ -91,9 +104,13 @@ implements ConnectionDecrypter {
 
 	@Override
 	public int read(byte[] b, int off, int len) throws IOException {
+		try {
 			if(betweenFrames) initialiseCipher();
 			if(bufLen == 0) {
-			if(!readBlock()) return -1;
+				if(!readBlock()) {
+					frameKey.erase();
+					return -1;
+				}
 				bufOff = 0;
 				bufLen = buf.length;
 			}
@@ -102,6 +119,10 @@ implements ConnectionDecrypter {
 			bufOff += length;
 			bufLen -= length;
 			return length;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	// Although we're using CTR mode, which doesn't require full blocks of

components/net/sf/briar/transport/ConnectionEncrypterImpl.java

@@ -46,6 +46,7 @@ implements ConnectionEncrypter {
 		}
 		if(encryptedIv.length != IV_LENGTH)
 			throw new IllegalArgumentException();
+		ivKey.erase();
 	}
 
 	public OutputStream getOutputStream() {
@@ -53,6 +54,7 @@ implements ConnectionEncrypter {
 	}
 
 	public void writeMac(byte[] mac) throws IOException {
+		try {
 			if(!ivWritten || betweenFrames) throw new IllegalStateException();
 			try {
 				out.write(frameCipher.doFinal(mac));
@@ -63,6 +65,10 @@ implements ConnectionEncrypter {
 			}
 			capacity -= mac.length;
 			betweenFrames = true;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	public long getRemainingCapacity() {
@@ -71,11 +77,16 @@ implements ConnectionEncrypter {
 
 	@Override
 	public void write(int b) throws IOException {
+		try {
 			if(!ivWritten) writeIv();
 			if(betweenFrames) initialiseCipher();
 			byte[] ciphertext = frameCipher.update(new byte[] {(byte) b});
 			if(ciphertext != null) out.write(ciphertext);
 			capacity--;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	@Override
@@ -85,11 +96,16 @@ implements ConnectionEncrypter {
 
 	@Override
 	public void write(byte[] b, int off, int len) throws IOException {
+		try {
 			if(!ivWritten) writeIv();
 			if(betweenFrames) initialiseCipher();
 			byte[] ciphertext = frameCipher.update(b, off, len);
 			if(ciphertext != null) out.write(ciphertext);
 			capacity -= len;
+		} catch(IOException e) {
+			frameKey.erase();
+			throw e;
+		}
 	}
 
 	private void writeIv() throws IOException {

components/net/sf/briar/transport/ConnectionReaderFactoryImpl.java

@@ -42,6 +42,7 @@ class ConnectionReaderFactoryImpl implements ConnectionReaderFactory {
 		} catch(InvalidKeyException badKey) {
 			throw new IllegalArgumentException(badKey);
 		}
+		ivKey.erase();
 		// Validate the IV
 		if(!IvEncoder.validateIv(iv, true, ctx))
 			throw new IllegalArgumentException();

components/net/sf/briar/transport/ConnectionReaderImpl.java

@@ -40,6 +40,7 @@ implements ConnectionReader {
 		} catch(InvalidKeyException e) {
 			throw new IllegalArgumentException(e);
 		}
+		macKey.erase();
 		maxPayloadLength = MAX_FRAME_LENGTH - 4 - mac.getMacLength();
 		header = new byte[4];
 		payload = new byte[maxPayloadLength];

components/net/sf/briar/transport/ConnectionRecogniserImpl.java

@@ -92,6 +92,7 @@ DatabaseListener {
 			byte[] secret = e.getValue();
 			ErasableKey ivKey = crypto.deriveIvKey(secret, true);
 			Bytes iv = new Bytes(encryptIv(i, unseen, ivKey));
+			ivKey.erase();
 			expected.put(iv, new ConnectionContextImpl(c, i, unseen, secret));
 		}
 	}

components/net/sf/briar/transport/ConnectionWriterFactoryImpl.java

@@ -47,6 +47,7 @@ class ConnectionWriterFactoryImpl implements ConnectionWriterFactory {
 		} catch(InvalidKeyException badKey) {
 			throw new RuntimeException(badKey);
 		}
+		ivKey.erase();
 		// Validate the IV
 		if(!IvEncoder.validateIv(iv, true, ctx))
 			throw new IllegalArgumentException();

components/net/sf/briar/transport/ConnectionWriterImpl.java

@@ -41,6 +41,7 @@ implements ConnectionWriter {
 		} catch(InvalidKeyException badKey) {
 			throw new IllegalArgumentException(badKey);
 		}
+		macKey.erase();
 		maxPayloadLength = MAX_FRAME_LENGTH - 4 - mac.getMacLength();
 		buf = new ByteArrayOutputStream(maxPayloadLength);
 		header = new byte[4];

test/net/sf/briar/transport/FrameReadWriteTest.java

@@ -74,12 +74,16 @@ public class FrameReadWriteTest extends TestCase {
 		random.nextBytes(frame);
 		byte[] frame1 = new byte[321];
 		random.nextBytes(frame1);
+		// Copy the keys - the copies will be erased
+		ErasableKey frameCopy = frameKey.copy();
+		ErasableKey ivCopy = ivKey.copy();
+		ErasableKey macCopy = macKey.copy();
 		// Write the frames
 		ByteArrayOutputStream out = new ByteArrayOutputStream();
 		ConnectionEncrypter encrypter = new ConnectionEncrypterImpl(out,
-				Long.MAX_VALUE, iv, ivCipher, frameCipher, ivKey, frameKey);
+				Long.MAX_VALUE, iv, ivCipher, frameCipher, ivCopy, frameCopy);
 		ConnectionWriter writer = new ConnectionWriterImpl(encrypter, mac,
-				macKey);
+				macCopy);
 		OutputStream out1 = writer.getOutputStream();
 		out1.write(frame);
 		out1.flush();