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new session reply

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orignal 2020-01-17 14:11:15 -05:00
parent 80373623cd
commit 62e39ddfbd
2 changed files with 73 additions and 2 deletions
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73
libi2pd/ECIESX25519AEADRatchetSession.cpp
View File

@ -34,7 +34,16 @@ namespace garlic
SHA256_Update (&ctx, buf, len);
SHA256_Final (m_H, &ctx);
}
void ECIESX25519AEADRatchetSession::DHInitialize (const uint8_t * rootKey, const uint8_t * k, uint8_t * nextRootKey, uint8_t * ck)
{
uint8_t keydata[64];
i2p::crypto::HKDF (rootKey, k, 32, "KDFDHRatchetStep", keydata); // keydata = HKDF(rootKey, k, "KDFDHRatchetStep", 64)
memcpy (nextRootKey, keydata, 32); // nextRootKey = keydata[0:31]
i2p::crypto::HKDF (keydata + 32, nullptr, 0, "TagAndKeyGenKeys", ck);
// ck = [sessTag_ck, symmKey_ck] = HKDF(keydata[32:63], ZEROLEN, "TagAndKeyGenKeys", 64)
}
bool ECIESX25519AEADRatchetSession::NewIncomingSession (const uint8_t * buf, size_t len, CloveHandler handleClove)
{
if (!GetOwner ()) return false;
@ -165,11 +174,66 @@ namespace garlic
LogPrint (eLogWarning, "Garlic: Payload section AEAD encryption failed");
return false;
}
MixHash (out + offset, len + 16); // h = SHA256(h || ciphertext)
MixHash (out + offset, 16); // h = SHA256(h || ciphertext)
return true;
}
bool ECIESX25519AEADRatchetSession::NewSessionReplyMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen)
{
m_EphemeralKeys.GenerateKeys ();
// we are Bob
uint8_t tagsetKey[32], ck[64];
i2p::crypto::HKDF (m_CK, nullptr, 0, "SessionReplyTags", tagsetKey, 32); // tagsetKey = HKDF(chainKey, ZEROLEN, "SessionReplyTags", 32)
DHInitialize (m_CK, tagsetKey, tagsetKey, ck); // tagset_nsr = DH_INITIALIZE(chainKey, tagsetKey), nextRootKey?
// Session Tag Ratchet
uint8_t keydata[64];
i2p::crypto::HKDF (ck, nullptr, 0, "STInitialization", keydata); // keydata = HKDF(sessTag_ck, ZEROLEN, "STInitialization", 64)
// sessTag_chainKey = keydata[0:31], SESSTAG_CONSTANT = keydata[32:63]
i2p::crypto::HKDF (keydata, keydata + 32, 32, "SessionTagKeyGen", keydata); // keydata_0 = HKDF(sessTag_chainkey, SESSTAG_CONSTANT, "SessionTagKeyGen", 64)
// tag_0 = keydata_0[32:39]
uint8_t * tag = keydata + 32;
size_t offset = 0;
memcpy (out + offset, tag, 8);
offset += 8;
if (!i2p::crypto::GetElligator ()->Encode (m_EphemeralKeys.GetPublicKey (), out + offset)) // bepk
{
LogPrint (eLogError, "Garlic: Can't encode elligator");
return false;
}
offset += 32;
// KDF for Reply Key Section
MixHash (tag, 8); // h = SHA256(h || tag)
MixHash (m_EphemeralKeys.GetPublicKey (), 32); // h = SHA256(h || bepk)
uint8_t sharedSecret[32];
m_EphemeralKeys.Agree (m_RemoteStaticKey, sharedSecret); // sharedSecret = x25519(besk, aepk)
i2p::crypto::HKDF (m_CK, sharedSecret, 32, "", m_CK); // [chainKey, key] = HKDF(chainKey, sharedSecret, "", 64)
uint8_t nonce[12];
memset (nonce, 0, 12); // n = 0
// calulate hash for zero length
if (!i2p::crypto::AEADChaCha20Poly1305 (sharedSecret /* can be anything */, 0, m_H, 32, m_CK + 32, nonce, out + offset, 16, true)) // encrypt, ciphertext = ENCRYPT(k, n, ZEROLEN, ad)
{
LogPrint (eLogWarning, "Garlic: Reply key section AEAD encryption failed");
return false;
}
MixHash (out + offset, 16); // h = SHA256(h || ciphertext)
out += 16;
// KDF for payload
i2p::crypto::HKDF (m_CK, nullptr, 0, "STInitialization", keydata); // keydata = HKDF(chainKey, ZEROLEN, "", 64)
// k_ab = keydata[0:31], k_ba = keydata[32:63]
// tagset_ab = DH_INITIALIZE(chainKey, k_ab), tagset_ba = DH_INITIALIZE(chainKey, k_ba)
i2p::crypto::HKDF (keydata + 32, nullptr, 0, "AttachPayloadKDF", keydata, 32); // k = HKDF(k_ba, ZEROLEN, "AttachPayloadKDF", 32)
// encrypt payload
if (!i2p::crypto::AEADChaCha20Poly1305 (payload, len, m_H, 32, keydata, nonce, out + offset, len + 16, true)) // encrypt
{
LogPrint (eLogWarning, "Garlic: Payload section AEAD encryption failed");
return false;
}
return true;
}
std::shared_ptr<I2NPMessage> ECIESX25519AEADRatchetSession::WrapSingleMessage (std::shared_ptr<const I2NPMessage> msg)
{
auto m = NewI2NPMessage ();
@ -185,6 +249,11 @@ namespace garlic
return nullptr;
len += 96;
break;
case eSessionStateNewSessionReceived:
if (!NewSessionReplyMessage (payload.data (), payload.size (), buf, m->maxLen))
return nullptr;
len += 72;
break;
default:
return nullptr;
}

2
libi2pd/ECIESX25519AEADRatchetSession.h
View File

@ -48,10 +48,12 @@ namespace garlic
private:
void MixHash (const uint8_t * buf, size_t len);
void DHInitialize (const uint8_t * rootKey, const uint8_t * k, uint8_t * nextRootKey, uint8_t * ck); // ck is 64 buytes
void HandlePayload (const uint8_t * buf, size_t len, CloveHandler& handleClove);
bool NewOutgoingSessionMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen);
bool NewSessionReplyMessage (const uint8_t * payload, size_t len, uint8_t * out, size_t outLen);
std::vector<uint8_t> CreatePayload (std::shared_ptr<const I2NPMessage> msg);
private: