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session key decryption

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orignal 2014-05-14 22:49:22 -04:00
parent 0a53555ac7
commit d3812786fa
2 changed files with 37 additions and 15 deletions
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41
SSU.cpp
View File

@ -29,7 +29,7 @@ namespace ssu
delete m_DHKeysPair;
}
void SSUSession::CreateAESandMacKey (const uint8_t * pubKey, uint8_t * aesKey, uint8_t * macKey)
void SSUSession::CreateAESandMacKey (const uint8_t * pubKey)
{
CryptoPP::DH dh (i2p::crypto::elgp, i2p::crypto::elgg);
uint8_t sharedKey[256];
@ -41,14 +41,14 @@ namespace ssu
if (sharedKey[0] & 0x80)
{
aesKey[0] = 0;
memcpy (aesKey + 1, sharedKey, 31);
memcpy (macKey, sharedKey + 31, 32);
m_SessionKey[0] = 0;
memcpy (m_SessionKey + 1, sharedKey, 31);
memcpy (m_MacKey, sharedKey + 31, 32);
}
else if (sharedKey[0])
{
memcpy (aesKey, sharedKey, 32);
memcpy (macKey, sharedKey + 32, 32);
memcpy (m_SessionKey, sharedKey, 32);
memcpy (m_MacKey, sharedKey + 32, 32);
}
else
{
@ -64,10 +64,11 @@ namespace ssu
}
}
memcpy (aesKey, nonZero, 32);
CryptoPP::SHA256().CalculateDigest(macKey, nonZero, 64 - (nonZero - sharedKey));
memcpy (m_SessionKey, nonZero, 32);
CryptoPP::SHA256().CalculateDigest(m_MacKey, nonZero, 64 - (nonZero - sharedKey));
}
m_IsSessionKey = true;
m_SessionKeyDecryption.SetKey (m_SessionKey);
}
void SSUSession::ProcessNextMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint)
@ -83,7 +84,7 @@ namespace ssu
{
ScheduleTermination ();
if (m_IsSessionKey && Validate (buf, len, m_MacKey)) // try session key first
Decrypt (buf, len, m_SessionKey);
DecryptSessionKey (buf, len);
else
{
// try intro key depending on side
@ -164,7 +165,7 @@ namespace ssu
m_State = eSessionStateRequestReceived;
LogPrint ("Session request received");
m_RemoteEndpoint = senderEndpoint;
CreateAESandMacKey (buf + sizeof (SSUHeader), m_SessionKey, m_MacKey);
CreateAESandMacKey (buf + sizeof (SSUHeader));
SendSessionCreated (buf + sizeof (SSUHeader));
}
@ -182,7 +183,7 @@ namespace ssu
uint8_t signedData[532]; // x,y, our IP, our port, remote IP, remote port, relayTag, signed on time
uint8_t * payload = buf + sizeof (SSUHeader);
uint8_t * y = payload;
CreateAESandMacKey (y, m_SessionKey, m_MacKey);
CreateAESandMacKey (y);
memcpy (signedData, m_DHKeysPair->publicKey, 256); // x
memcpy (signedData + 256, y, 256); // y
payload += 256;
@ -523,6 +524,24 @@ namespace ssu
m_Decryption.ProcessData (encrypted, encrypted, encryptedLen);
}
void SSUSession::DecryptSessionKey (uint8_t * buf, size_t len)
{
if (len < sizeof (SSUHeader))
{
LogPrint ("Unexpected SSU packet length ", len);
return;
}
SSUHeader * header = (SSUHeader *)buf;
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
encryptedLen = (encryptedLen>>4)<<4; // make sure 16 bytes boundary
if (encryptedLen > 0)
{
m_SessionKeyDecryption.SetIV (header->iv);
m_SessionKeyDecryption.Decrypt (encrypted, encryptedLen, encrypted);
}
}
bool SSUSession::Validate (uint8_t * buf, size_t len, const uint8_t * macKey)
{
if (len < sizeof (SSUHeader))

11
SSU.h
View File

@ -9,6 +9,7 @@
#include <boost/asio.hpp>
#include <cryptopp/modes.h>
#include <cryptopp/aes.h>
#include "aes.h"
#include "I2PEndian.h"
#include "Identity.h"
#include "RouterInfo.h"
@ -85,7 +86,7 @@ namespace ssu
private:
void CreateAESandMacKey (const uint8_t * pubKey, uint8_t * aesKey, uint8_t * macKey);
void CreateAESandMacKey (const uint8_t * pubKey);
void ProcessMessage (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint); // call for established session
void ProcessSessionRequest (uint8_t * buf, size_t len, const boost::asio::ip::udp::endpoint& senderEndpoint);
@ -112,7 +113,8 @@ namespace ssu
void Send (uint8_t type, const uint8_t * payload, size_t len); // with session key
void FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len, const uint8_t * aesKey, const uint8_t * iv, const uint8_t * macKey);
void Decrypt (uint8_t * buf, size_t len, const uint8_t * aesKey);
void Decrypt (uint8_t * buf, size_t len, const uint8_t * aesKey);
void DecryptSessionKey (uint8_t * buf, size_t len);
bool Validate (uint8_t * buf, size_t len, const uint8_t * macKey);
const uint8_t * GetIntroKey () const;
@ -132,8 +134,9 @@ namespace ssu
bool m_IsSessionKey;
uint32_t m_RelayTag;
std::set<uint32_t> m_PeerTestNonces;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption;
CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption m_Decryption;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption; // TODO: remove
CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption m_Decryption; // TODO: remove
i2p::crypto::CBCDecryption m_SessionKeyDecryption;
uint8_t m_SessionKey[32], m_MacKey[32];
std::list<i2p::I2NPMessage *> m_DelayedMessages;
SSUData m_Data;