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Added interfaces for reading and writing packets and recognising which

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contact originated an incoming connection, and an implementation of
the PacketWriter interface.
This commit is contained in:
akwizgran
2011-08-09 16:15:25 +01:00
parent 18654f1514
commit e9d0021f56
8 changed files with 351 additions and 1 deletions
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27
components/net/sf/briar/crypto/CryptoComponentImpl.java
View File

@@ -8,6 +8,10 @@ import java.security.NoSuchProviderException;
import java.security.Security;
import java.security.Signature;
import javax.crypto.KeyGenerator;
import javax.crypto.Mac;
import javax.crypto.SecretKey;
import net.sf.briar.api.crypto.CryptoComponent;
import net.sf.briar.api.crypto.KeyParser;
@@ -18,11 +22,15 @@ class CryptoComponentImpl implements CryptoComponent {
private static final String PROVIDER = "BC";
private static final String DIGEST_ALGO = "SHA-256";
private static final String KEY_PAIR_ALGO = "ECDSA";
private static final int KEY_PAIR_KEYSIZE = 256;
private static final int KEY_PAIR_KEYSIZE = 256; // Bits
private static final String MAC_ALGO = "HMacSHA256";
private static final String SECRET_KEY_ALGO = "AES";
private static final int SECRET_KEY_KEYSIZE = 256; // Bits
private static final String SIGNATURE_ALGO = "ECDSA";
private final KeyParser keyParser;
private final KeyPairGenerator keyPairGenerator;
private final KeyGenerator keyGenerator;
CryptoComponentImpl() {
Security.addProvider(new BouncyCastleProvider());
@@ -31,6 +39,9 @@ class CryptoComponentImpl implements CryptoComponent {
keyPairGenerator = KeyPairGenerator.getInstance(KEY_PAIR_ALGO,
PROVIDER);
keyPairGenerator.initialize(KEY_PAIR_KEYSIZE);
keyGenerator = KeyGenerator.getInstance(SECRET_KEY_ALGO,
PROVIDER);
keyGenerator.init(SECRET_KEY_KEYSIZE);
} catch(NoSuchAlgorithmException impossible) {
throw new RuntimeException(impossible);
} catch(NoSuchProviderException impossible) {
@@ -42,10 +53,24 @@ class CryptoComponentImpl implements CryptoComponent {
return keyPairGenerator.generateKeyPair();
}
public SecretKey generateSecretKey() {
return keyGenerator.generateKey();
}
public KeyParser getKeyParser() {
return keyParser;
}
public Mac getMac() {
try {
return Mac.getInstance(MAC_ALGO, PROVIDER);
} catch(NoSuchAlgorithmException impossible) {
throw new RuntimeException(impossible);
} catch(NoSuchProviderException impossible) {
throw new RuntimeException(impossible);
}
}
public MessageDigest getMessageDigest() {
try {
return MessageDigest.getInstance(DIGEST_ALGO, PROVIDER);

105
components/net/sf/briar/transport/PacketWriterImpl.java Normal file
View File

@@ -0,0 +1,105 @@
package net.sf.briar.transport;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.crypto.Mac;
import net.sf.briar.api.transport.PacketWriter;
class PacketWriterImpl extends FilterOutputStream implements PacketWriter {
private static final int MAX_16_BIT_UNSIGNED = 65535; // 2^16 - 1
private static final long MAX_32_BIT_UNSIGNED = 4294967295L; // 2^32 - 1
private final Mac mac;
private final int transportIdentifier;
private final long connectionNumber;
private long packetNumber = 0L;
private boolean betweenPackets = true;
PacketWriterImpl(OutputStream out, Mac mac, int transportIdentifier,
long connectionNumber) {
super(out);
this.mac = mac;
if(transportIdentifier < 0) throw new IllegalArgumentException();
if(transportIdentifier > MAX_16_BIT_UNSIGNED)
throw new IllegalArgumentException();
this.transportIdentifier = transportIdentifier;
if(connectionNumber < 0L) throw new IllegalArgumentException();
if(connectionNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException();
this.connectionNumber = connectionNumber;
}
public OutputStream getOutputStream() {
return this;
}
public void nextPacket() throws IOException {
if(!betweenPackets) writeMac();
}
@Override
public void write(int b) throws IOException {
if(betweenPackets) writeTag();
out.write(b);
mac.update((byte) b);
}
@Override
public void write(byte[] b) throws IOException {
if(betweenPackets) writeTag();
out.write(b);
mac.update(b);
}
@Override
public void write(byte[] b, int len, int off) throws IOException {
if(betweenPackets) writeTag();
out.write(b, len, off);
mac.update(b, len, off);
}
private void writeMac() throws IOException {
out.write(mac.doFinal());
betweenPackets = true;
}
private void writeTag() throws IOException {
if(packetNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalStateException();
byte[] tag = new byte[16];
// Encode the transport identifier as an unsigned 16-bit integer
writeUint16(transportIdentifier, tag, 2);
// Encode the connection number as an unsigned 32-bit integer
writeUint32(connectionNumber, tag, 4);
// Encode the packet number as an unsigned 32-bit integer
writeUint32(packetNumber, tag, 8);
// Write the tag to the underlying output stream and the MAC
out.write(tag);
mac.update(tag);
packetNumber++;
betweenPackets = false;
}
private void writeUint16(int i, byte[] b, int offset) {
assert i >= 0;
assert i <= MAX_16_BIT_UNSIGNED;
assert b.length >= offset + 2;
b[offset] = (byte) (i >> 8);
b[offset + 1] = (byte) (i & 0xFF);
}
private void writeUint32(long i, byte[] b, int offset) {
assert i >= 0L;
assert i <= MAX_32_BIT_UNSIGNED;
assert b.length >= offset + 4;
b[offset] = (byte) (i >> 24);
b[offset + 1] = (byte) (i >> 16 & 0xFF);
b[offset + 2] = (byte) (i >> 8 & 0xFF);
b[offset + 3] = (byte) (i & 0xFF);
}
}