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some refactoring of NTCP2 code

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pull/1212/head
orignal 6 years ago
parent 6054bd6621
commit 5218c8584f
2 changed files with 79 additions and 57 deletions
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110
libi2pd/NTCP2.cpp
Unescape Escape View File

@ -15,6 +15,17 @@ namespace i2p
{
namespace transport
{
NTCP2Establisher::NTCP2Establisher ()
{
m_Ctx = BN_CTX_new ();
CreateEphemeralKey ();
}
NTCP2Establisher::~NTCP2Establisher ()
{
BN_CTX_free (m_Ctx);
}
void NTCP2Establisher::MixKey (const uint8_t * inputKeyMaterial, uint8_t * derived)
{
// temp_key = HMAC-SHA256(ck, input_key_material)
@ -28,7 +39,7 @@ namespace transport
HMAC(EVP_sha256(), tempKey, 32, m_CK, 33, derived, &len);
}
void NTCP2Establisher::KeyDerivationFunction1 (const uint8_t * rs, const uint8_t * priv, const uint8_t * pub, uint8_t * derived)
void NTCP2Establisher::KeyDerivationFunction1 (const uint8_t * rs, const uint8_t * priv, const uint8_t * pub)
{
static const uint8_t protocolNameHash[] =
{
@ -50,10 +61,20 @@ namespace transport
// x25519 between rs and priv
uint8_t inputKeyMaterial[32];
i2p::crypto::GetEd25519 ()->ScalarMul (rs, priv, inputKeyMaterial, m_Ctx); // rs*priv
MixKey (inputKeyMaterial, derived);
MixKey (inputKeyMaterial, m_K);
}
void NTCP2Establisher::KDF1Alice ()
{
KeyDerivationFunction1 (m_RemoteStaticKey, GetPriv (), GetPub ());
}
void NTCP2Establisher::KDF1Bob ()
{
KeyDerivationFunction1 (GetRemotePub (), i2p::context.GetNTCP2StaticPrivateKey (), GetRemotePub ());
}
void NTCP2Establisher::KeyDerivationFunction2 (const uint8_t * priv, const uint8_t * pub, const uint8_t * sessionRequest, size_t sessionRequestLen, uint8_t * derived)
void NTCP2Establisher::KeyDerivationFunction2 (const uint8_t * sessionRequest, size_t sessionRequestLen)
{
uint8_t h[64];
memcpy (h, m_H, 32);
@ -62,24 +83,32 @@ namespace transport
int paddingLength = sessionRequestLen - 64;
if (paddingLength > 0)
{
std::vector<uint8_t> h1(paddingLength + 32);
memcpy (h1.data (), h, 32);
memcpy (h1.data () + 32, sessionRequest + 64, paddingLength);
SHA256 (h1.data (), paddingLength + 32, h);
SHA256_CTX ctx;
SHA256_Init (&ctx);
SHA256_Update (&ctx, h, 32);
SHA256_Update (&ctx, sessionRequest + 64, paddingLength);
SHA256_Final (h, &ctx);
}
memcpy (h + 32, pub, 32);
memcpy (h + 32, GetRemotePub (), 32);
SHA256 (h, 64, m_H);
// x25519 between remote pub and priv
uint8_t inputKeyMaterial[32];
i2p::crypto::GetEd25519 ()->ScalarMul (pub, priv, inputKeyMaterial, m_Ctx);
MixKey (inputKeyMaterial, derived);
i2p::crypto::GetEd25519 ()->ScalarMul (GetRemotePub (), GetPriv (), inputKeyMaterial, m_Ctx);
MixKey (inputKeyMaterial, m_K);
}
void NTCP2Establisher::CreateEphemeralKey (uint8_t * pub)
void NTCP2Establisher::KeyDerivationFunction3 (const uint8_t * staticPrivKey)
{
uint8_t inputKeyMaterial[32];
i2p::crypto::GetEd25519 ()->ScalarMul (GetRemotePub (), staticPrivKey, inputKeyMaterial, m_Ctx);
MixKey (inputKeyMaterial, m_K);
}
void NTCP2Establisher::CreateEphemeralKey ()
{
RAND_bytes (m_EphemeralPrivateKey, 32);
i2p::crypto::GetEd25519 ()->ScalarMulB (m_EphemeralPrivateKey, pub, m_Ctx);
i2p::crypto::GetEd25519 ()->ScalarMulB (m_EphemeralPrivateKey, m_EphemeralPublicKey, m_Ctx);
}
NTCP2Session::NTCP2Session (NTCP2Server& server, std::shared_ptr<const i2p::data::RouterInfo> in_RemoteRouter):
@ -133,15 +162,6 @@ namespace transport
}
void NTCP2Session::KeyDerivationFunction3 (const uint8_t * staticPrivKey, uint8_t * derived)
{
uint8_t inputKeyMaterial[32];
BN_CTX * ctx = BN_CTX_new ();
i2p::crypto::GetEd25519 ()->ScalarMul (m_Establisher->m_Y, staticPrivKey, inputKeyMaterial, ctx);
BN_CTX_free (ctx);
m_Establisher->MixKey (inputKeyMaterial, derived);
}
void NTCP2Session::KeyDerivationFunctionDataPhase ()
{
uint8_t tempKey[32]; unsigned int len;
@ -171,18 +191,14 @@ namespace transport
m_SessionRequestBufferLen = paddingLength + 64;
m_SessionRequestBuffer = new uint8_t[m_SessionRequestBufferLen];
RAND_bytes (m_SessionRequestBuffer + 64, paddingLength);
// generate key pair (X)
uint8_t x[32];
m_Establisher->CreateEphemeralKey (x);
// encrypt X
i2p::crypto::CBCEncryption encryption;
encryption.SetKey (GetRemoteIdentity ()->GetIdentHash ());
encryption.SetIV (m_Establisher->m_IV);
encryption.Encrypt (x, 32, m_SessionRequestBuffer);
encryption.Encrypt (m_Establisher->GetPub (), 32, m_SessionRequestBuffer); // X
encryption.GetIV (m_Establisher->m_IV); // save IV for SessionCreated
// encryption key for next block
uint8_t key[32];
m_Establisher->KeyDerivationFunction1 (m_Establisher->m_RemoteStaticKey, m_Establisher->m_EphemeralPrivateKey, x, key);
m_Establisher->KDF1Alice ();
// fill options
uint8_t options[32]; // actual options size is 16 bytes
memset (options, 0, 16);
@ -195,7 +211,7 @@ namespace transport
// sign and encrypt options, use m_H as AD
uint8_t nonce[12];
memset (nonce, 0, 12); // set nonce to zero
i2p::crypto::AEADChaCha20Poly1305 (options, 16, m_Establisher->GetH (), 32, key, nonce, m_SessionRequestBuffer + 32, 32, true); // encrypt
i2p::crypto::AEADChaCha20Poly1305 (options, 16, m_Establisher->GetH (), 32, m_Establisher->GetK (), nonce, m_SessionRequestBuffer + 32, 32, true); // encrypt
// send message
boost::asio::async_write (m_Socket, boost::asio::buffer (m_SessionRequestBuffer, m_SessionRequestBufferLen), boost::asio::transfer_all (),
std::bind(&NTCP2Session::HandleSessionRequestSent, shared_from_this (), std::placeholders::_1, std::placeholders::_2));
@ -232,15 +248,14 @@ namespace transport
i2p::crypto::CBCDecryption decryption;
decryption.SetKey (i2p::context.GetIdentHash ());
decryption.SetIV (i2p::context.GetNTCP2IV ());
decryption.Decrypt (m_SessionRequestBuffer, 32, m_Establisher->m_Y);
decryption.Decrypt (m_SessionRequestBuffer, 32, m_Establisher->GetRemotePub ());
decryption.GetIV (m_Establisher->m_IV); // save IV for SessionCreated
// decryption key for next block
uint8_t key[32];
m_Establisher->KeyDerivationFunction1 (m_Establisher->m_Y, i2p::context.GetNTCP2StaticPrivateKey (), m_Establisher->m_Y, key);
m_Establisher->KDF1Bob ();
// verify MAC and decrypt options block (32 bytes), use m_H as AD
uint8_t nonce[12], options[16];
memset (nonce, 0, 12); // set nonce to zero
if (i2p::crypto::AEADChaCha20Poly1305 (m_SessionRequestBuffer + 32, 16, m_Establisher->GetH (), 32, key, nonce, options, 16, false)) // decrypt
if (i2p::crypto::AEADChaCha20Poly1305 (m_SessionRequestBuffer + 32, 16, m_Establisher->GetH (), 32, m_Establisher->GetK (), nonce, options, 16, false)) // decrypt
{
if (options[1] == 2)
{
@ -281,16 +296,13 @@ namespace transport
void NTCP2Session::SendSessionCreated ()
{
m_SessionCreatedBuffer = new uint8_t[287]; // TODO: determine actual max size
// generate key pair (y)
uint8_t y[32];
m_Establisher->CreateEphemeralKey (y);
// encrypt Y
i2p::crypto::CBCEncryption encryption;
encryption.SetKey (i2p::context.GetIdentHash ());
encryption.SetIV (m_Establisher->m_IV);
encryption.Encrypt (y, 32, m_SessionCreatedBuffer);
encryption.Encrypt (m_Establisher->GetPub (), 32, m_SessionCreatedBuffer); // Y
// encryption key for next block (m_K)
m_Establisher->KeyDerivationFunction2 (m_Establisher->m_EphemeralPrivateKey, m_Establisher->m_Y, m_SessionRequestBuffer, m_SessionRequestBufferLen, m_Establisher->m_K);
m_Establisher->KeyDerivationFunction2 (m_SessionRequestBuffer, m_SessionRequestBufferLen);
auto paddingLen = rand () % (287 - 64);
uint8_t options[16];
memset (options, 0, 16);
@ -299,7 +311,7 @@ namespace transport
// sign and encrypt options, use m_H as AD
uint8_t nonce[12];
memset (nonce, 0, 12); // set nonce to zero
i2p::crypto::AEADChaCha20Poly1305 (options, 16, m_Establisher->m_H, 32, m_Establisher->m_K, nonce, m_SessionCreatedBuffer + 32, 32, true); // encrypt
i2p::crypto::AEADChaCha20Poly1305 (options, 16, m_Establisher->GetH (), 32, m_Establisher->GetK (), nonce, m_SessionCreatedBuffer + 32, 32, true); // encrypt
// fill padding
RAND_bytes (m_SessionCreatedBuffer + 56, paddingLen);
// send message
@ -322,14 +334,14 @@ namespace transport
i2p::crypto::CBCDecryption decryption;
decryption.SetKey (GetRemoteIdentity ()->GetIdentHash ());
decryption.SetIV (m_Establisher->m_IV);
decryption.Decrypt (m_SessionCreatedBuffer, 32, m_Establisher->m_Y);
decryption.Decrypt (m_SessionCreatedBuffer, 32, m_Establisher->GetRemotePub ());
// decryption key for next block (m_K)
m_Establisher->KeyDerivationFunction2 (m_Establisher->m_EphemeralPrivateKey, m_Establisher->m_Y, m_SessionRequestBuffer, m_SessionRequestBufferLen, m_Establisher->m_K);
m_Establisher->KeyDerivationFunction2 (m_SessionRequestBuffer, m_SessionRequestBufferLen);
// decrypt and verify MAC
uint8_t payload[16];
uint8_t nonce[12];
memset (nonce, 0, 12); // set nonce to zero
if (i2p::crypto::AEADChaCha20Poly1305 (m_SessionCreatedBuffer + 32, 16, m_Establisher->GetH (), 32, m_Establisher->m_K, nonce, payload, 16, false)) // decrypt
if (i2p::crypto::AEADChaCha20Poly1305 (m_SessionCreatedBuffer + 32, 16, m_Establisher->GetH (), 32, m_Establisher->GetK (), nonce, payload, 16, false)) // decrypt
{
uint16_t paddingLen = bufbe16toh(payload + 2);
LogPrint (eLogDebug, "NTCP2: padding length ", paddingLen);
@ -375,16 +387,17 @@ namespace transport
int paddingLength = m_SessionCreatedBufferLen - 64;
if (paddingLength > 0)
{
std::vector<uint8_t> h1(paddingLength + 32);
memcpy (h1.data (), h, 32);
memcpy (h1.data () + 32, m_SessionCreatedBuffer + 64, paddingLength);
SHA256 (h1.data (), paddingLength + 32, h);
SHA256_CTX ctx;
SHA256_Init (&ctx);
SHA256_Update (&ctx, h, 32);
SHA256_Update (&ctx, m_SessionCreatedBuffer + 64, paddingLength);
SHA256_Final (h, &ctx);
}
// part1 48 bytes
m_SessionConfirmedBuffer = new uint8_t[2048]; // TODO: actual size
uint8_t nonce[12];
CreateNonce (1, nonce);
i2p::crypto::AEADChaCha20Poly1305 (i2p::context.GetNTCP2StaticPublicKey (), 32, h, 32, m_Establisher->m_K, nonce, m_SessionConfirmedBuffer, 48, true); // encrypt
i2p::crypto::AEADChaCha20Poly1305 (i2p::context.GetNTCP2StaticPublicKey (), 32, h, 32, m_Establisher->GetK (), nonce, m_SessionConfirmedBuffer, 48, true); // encrypt
// part 2
// update AD again
memcpy (h + 32, m_SessionConfirmedBuffer, 48);
@ -396,10 +409,9 @@ namespace transport
htobe16buf (buf.data () + 1, i2p::context.GetRouterInfo ().GetBufferLen () + 1); // flag + RI
buf[3] = 0; // flag
memcpy (buf.data () + 4, i2p::context.GetRouterInfo ().GetBuffer (), i2p::context.GetRouterInfo ().GetBufferLen ());
uint8_t key[32];
KeyDerivationFunction3 (i2p::context.GetNTCP2StaticPrivateKey (), key);
m_Establisher->KeyDerivationFunction3 (i2p::context.GetNTCP2StaticPrivateKey ());
memset (nonce, 0, 12); // set nonce to 0 again
i2p::crypto::AEADChaCha20Poly1305 (buf.data (), m3p2Len - 16, m_Establisher->GetH (), 32, key, nonce, m_SessionConfirmedBuffer + 48, m3p2Len, true); // encrypt
i2p::crypto::AEADChaCha20Poly1305 (buf.data (), m3p2Len - 16, m_Establisher->GetH (), 32, m_Establisher->GetK (), nonce, m_SessionConfirmedBuffer + 48, m3p2Len, true); // encrypt
uint8_t tmp[48];
memcpy (tmp, m_SessionConfirmedBuffer, 48);
memcpy (m_SessionConfirmedBuffer + 16, m_Establisher->GetH (), 32); // h || ciphertext

26
libi2pd/NTCP2.h
Unescape Escape View File

@ -15,20 +15,31 @@ namespace transport
{
struct NTCP2Establisher
{
NTCP2Establisher () { m_Ctx = BN_CTX_new (); };
~NTCP2Establisher () { BN_CTX_free (m_Ctx); };
NTCP2Establisher ();
~NTCP2Establisher ();
const uint8_t * GetPub () const { return m_EphemeralPublicKey; };
const uint8_t * GetPriv () const { return m_EphemeralPrivateKey; };
const uint8_t * GetRemotePub () const { return m_RemoteEphemeralPublicKey; }; // Y for Alice and X for Bob
uint8_t * GetRemotePub () { return m_RemoteEphemeralPublicKey; }; // to set
const uint8_t * GetK () const { return m_K; };
const uint8_t * GetCK () const { return m_CK; };
const uint8_t * GetH () const { return m_H; };
void KDF1Alice ();
void KDF1Bob ();
void MixKey (const uint8_t * inputKeyMaterial, uint8_t * derived);
void KeyDerivationFunction1 (const uint8_t * rs, const uint8_t * priv, const uint8_t * pub, uint8_t * derived); // for SessionRequest
void KeyDerivationFunction2 (const uint8_t * priv, const uint8_t * pub, const uint8_t * sessionRequest, size_t sessionRequestLen, uint8_t * derived); // for SessionCreate
void CreateEphemeralKey (uint8_t * pub);
void KeyDerivationFunction1 (const uint8_t * rs, const uint8_t * priv, const uint8_t * pub); // for SessionRequest
void KeyDerivationFunction2 (const uint8_t * sessionRequest, size_t sessionRequestLen); // for SessionCreate
void KeyDerivationFunction3 (const uint8_t * staticPrivKey); // for SessionConfirmed part 2
void CreateEphemeralKey ();
BN_CTX * m_Ctx;
uint8_t m_EphemeralPrivateKey[32]; // x25519
uint8_t m_RemoteStaticKey[32], m_IV[16], m_H[32] /*h*/, m_CK[33] /*ck*/, m_K[32] /* derived after SessionCreated */, m_Y[32] /* or X for Bob */;
uint8_t m_EphemeralPrivateKey[32], m_EphemeralPublicKey[32], m_RemoteEphemeralPublicKey[32]; // x25519
uint8_t m_RemoteStaticKey[32], m_IV[16], m_H[32] /*h*/, m_CK[33] /*ck*/, m_K[32] /*k*/;
};
@ -51,7 +62,6 @@ namespace transport
private:
void CreateNonce (uint64_t seqn, uint8_t * nonce);
void KeyDerivationFunction3 (const uint8_t * staticPrivKey, uint8_t * derived); // for SessionConfirmed part 2
void KeyDerivationFunctionDataPhase ();
// establish

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