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use CBCEncryption for session key encryption

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orignal 2014-06-01 19:51:27 -04:00
parent 0d51f240d0
commit 6518727270
2 changed files with 32 additions and 19 deletions
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49
SSU.cpp
View File

@ -68,6 +68,7 @@ namespace ssu
CryptoPP::SHA256().CalculateDigest(m_MacKey, nonZero, 64 - (nonZero - sharedKey));
}
m_IsSessionKey = true;
m_SessionKeyEncryption.SetKey (m_SessionKey);
m_SessionKeyDecryption.SetKey (m_SessionKey);
}
@ -509,6 +510,28 @@ namespace ssu
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, macKey, header->mac);
}
void SSUSession::FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len)
{
if (len < sizeof (SSUHeader))
{
LogPrint ("Unexpected SSU packet length ", len);
return;
}
SSUHeader * header = (SSUHeader *)buf;
i2p::context.GetRandomNumberGenerator ().GenerateBlock (header->iv, 16); // random iv
m_SessionKeyEncryption.SetIV (header->iv);
header->flag = payloadType << 4; // MSB is 0
header->time = htobe32 (i2p::util::GetSecondsSinceEpoch ());
uint8_t * encrypted = &header->flag;
uint16_t encryptedLen = len - (encrypted - buf);
encryptedLen = (encryptedLen>>4)<<4; // make sure 16 bytes boundary, TODO: do we really need it?
m_SessionKeyEncryption.Encrypt (encrypted, encryptedLen, encrypted);
// assume actual buffer size is 18 (16 + 2) bytes more
memcpy (buf + len, header->iv, 16);
*(uint16_t *)(buf + len + 16) = htobe16 (encryptedLen);
i2p::crypto::HMACMD5Digest (encrypted, encryptedLen + 18, m_MacKey, header->mac);
}
void SSUSession::Decrypt (uint8_t * buf, size_t len, const uint8_t * aesKey)
{
if (len < sizeof (SSUHeader))
@ -790,17 +813,14 @@ namespace ssu
memset (payload, 0, 6); // address and port always zero for Alice
payload += 6; // address and port
memcpy (payload, introKey, 32); // intro key
uint8_t iv[16];
rnd.GenerateBlock (iv, 16); // random iv
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_PEER_TEST, buf, 80, m_SessionKey, iv, m_MacKey);
FillHeaderAndEncrypt (PAYLOAD_TYPE_PEER_TEST, buf, 80);
m_Server.Send (buf, 80, m_RemoteEndpoint);
}
void SSUSession::SendMsgAck (uint32_t msgID)
{
uint8_t buf[48 + 18]; // actual length is 44 = 37 + 7 but pad it to multiple of 16
uint8_t iv[16];
uint8_t * payload = buf + sizeof (SSUHeader);
*payload = DATA_FLAG_EXPLICIT_ACKS_INCLUDED; // flag
payload++;
@ -810,10 +830,8 @@ namespace ssu
payload += 4;
*payload = 0; // number of fragments
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_DATA, buf, 48, m_SessionKey, iv, m_MacKey);
FillHeaderAndEncrypt (PAYLOAD_TYPE_DATA, buf, 48);
m_Server.Send (buf, 48, m_RemoteEndpoint);
}
@ -821,11 +839,9 @@ namespace ssu
{
if (m_IsSessionKey)
{
uint8_t buf[48 + 18], iv[16];
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
uint8_t buf[48 + 18];
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_DESTROYED, buf, 48, m_SessionKey, iv, m_MacKey);
FillHeaderAndEncrypt (PAYLOAD_TYPE_SESSION_DESTROYED, buf, 48);
m_Server.Send (buf, 48, m_RemoteEndpoint);
}
}
@ -840,7 +856,7 @@ namespace ssu
uint32_t fragmentNum = 0;
while (len > 0)
{
uint8_t buf[SSU_MTU + 18], iv[16], * payload = buf + sizeof (SSUHeader);
uint8_t buf[SSU_MTU + 18], * payload = buf + sizeof (SSUHeader);
*payload = DATA_FLAG_WANT_REPLY; // for compatibility
payload++;
*payload = 1; // always 1 message fragment per message
@ -863,10 +879,8 @@ namespace ssu
if (size & 0x0F) // make sure 16 bytes boundary
size = ((size >> 4) + 1) << 4; // (/16 + 1)*16
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
// encrypt message with session key
FillHeaderAndEncrypt (PAYLOAD_TYPE_DATA, buf, size, m_SessionKey, iv, m_MacKey);
FillHeaderAndEncrypt (PAYLOAD_TYPE_DATA, buf, size);
m_Server.Send (buf, size, m_RemoteEndpoint);
if (!isLast)
@ -884,7 +898,6 @@ namespace ssu
void SSUSession::Send (uint8_t type, const uint8_t * payload, size_t len)
{
uint8_t buf[SSU_MTU + 18];
uint8_t iv[16];
size_t msgSize = len + sizeof (SSUHeader);
if (msgSize > SSU_MTU)
{
@ -892,10 +905,8 @@ namespace ssu
return;
}
memcpy (buf + sizeof (SSUHeader), payload, len);
CryptoPP::RandomNumberGenerator& rnd = i2p::context.GetRandomNumberGenerator ();
rnd.GenerateBlock (iv, 16); // random iv
// encrypt message with session key
FillHeaderAndEncrypt (type, buf, msgSize, m_SessionKey, iv, m_MacKey);
FillHeaderAndEncrypt (type, buf, msgSize);
m_Server.Send (buf, msgSize, m_RemoteEndpoint);
}

2
SSU.h
View File

@ -113,6 +113,7 @@ 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 FillHeaderAndEncrypt (uint8_t payloadType, uint8_t * buf, size_t len); // with session key
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);
@ -136,6 +137,7 @@ namespace ssu
std::set<uint32_t> m_PeerTestNonces;
CryptoPP::CBC_Mode<CryptoPP::AES>::Encryption m_Encryption; // TODO: remove
CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption m_Decryption; // TODO: remove
i2p::crypto::CBCEncryption m_SessionKeyEncryption;
i2p::crypto::CBCDecryption m_SessionKeyDecryption;
uint8_t m_SessionKey[32], m_MacKey[32];
std::list<i2p::I2NPMessage *> m_DelayedMessages;