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* SSU:

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- Ignore padding beyond last multiple of 16 (prep for obfuscation)
  - Comment out xor with 0 (version)
  - Don't need to zero IV buf before overwriting
* AES:
  - Decrypt speedup by XOR in place
  - Log if decrypt not mod 16
This commit is contained in:
zzz
2013-06-21 19:21:02 +00:00
parent 322e76d2a9
commit bb100de702
3 changed files with 31 additions and 9 deletions
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7
router/java/src/net/i2p/router/transport/udp/PacketBuilder.java
View File

@@ -121,8 +121,11 @@ class PacketBuilder {
static final int TYPE_SREQ = 52;
static final int TYPE_CREAT = 53;
/** we only talk to people of the right version */
/** we only talk to people of the right version
* Commented out to prevent findbugs noop complaint
* If we ever change this, uncomment below and in UDPPacket
static final int PROTOCOL_VERSION = 0;
*/
/** if no extended options or rekey data, which we don't support = 37 */
public static final int HEADER_SIZE = UDPPacket.MAC_SIZE + UDPPacket.IV_SIZE + 1 + 4;
@@ -1317,7 +1320,7 @@ class PacketBuilder {
off += encryptSize;
System.arraycopy(iv, 0, data, off, UDPPacket.IV_SIZE);
off += UDPPacket.IV_SIZE;
DataHelper.toLong(data, off, 2, encryptSize ^ PROTOCOL_VERSION);
DataHelper.toLong(data, off, 2, encryptSize /* ^ PROTOCOL_VERSION */ );
int hmacOff = packet.getPacket().getOffset();
int hmacLen = encryptSize + UDPPacket.IV_SIZE + 2;

14
router/java/src/net/i2p/router/transport/udp/UDPPacket.java
View File

@@ -202,7 +202,7 @@ class UDPPacket implements CDQEntry {
off += payloadLength;
System.arraycopy(_data, _packet.getOffset() + MAC_SIZE, _validateBuf, off, IV_SIZE);
off += IV_SIZE;
DataHelper.toLong(_validateBuf, off, 2, payloadLength ^ PacketBuilder.PROTOCOL_VERSION);
DataHelper.toLong(_validateBuf, off, 2, payloadLength /* ^ PacketBuilder.PROTOCOL_VERSION */ );
off += 2;
eq = _context.hmac().verify(macKey, _validateBuf, 0, off, _data, _packet.getOffset(), MAC_SIZE);
@@ -241,10 +241,18 @@ class UDPPacket implements CDQEntry {
*/
public void decrypt(SessionKey cipherKey) {
verifyNotReleased();
Arrays.fill(_ivBuf, (byte)0);
System.arraycopy(_data, MAC_SIZE, _ivBuf, 0, IV_SIZE);
int len = _packet.getLength();
_context.aes().decrypt(_data, _packet.getOffset() + MAC_SIZE + IV_SIZE, _data, _packet.getOffset() + MAC_SIZE + IV_SIZE, cipherKey, _ivBuf, len - MAC_SIZE - IV_SIZE);
// As of 0.9.7, ignore padding beyond the last mod 16,
// it could otherwise blow up in decryption.
// This allows for better obfuscation.
// Probably works without this since _data is bigger than necessary, but let's not
// bother decrypting and risk overrun.
int rem = len & 0x0f;
if (rem != 0)
len -= rem;
int off = _packet.getOffset() + MAC_SIZE + IV_SIZE;
_context.aes().decrypt(_data, off, _data, off, cipherKey, _ivBuf, len - MAC_SIZE - IV_SIZE);
}
/**