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KeyDerivationFunction for NTCP2

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orignal 2018-06-05 15:37:08 -04:00
parent 86c1984982
commit 8c9eaccc11
4 changed files with 41 additions and 0 deletions
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31
libi2pd/NTCP2.cpp
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@ -1,4 +1,6 @@
#include <openssl/rand.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include "Crypto.h"
#include "Ed25519.h"
#include "ChaCha20.h"
@ -18,6 +20,35 @@ namespace transport
{
}
bool NTCP2Session::KeyDerivationFunction (const uint8_t * rs, const uint8_t * pub, uint8_t * derived)
{
static const char protocolName[] = "Noise_XK_25519_ChaChaPoly_SHA256"; // 32 bytes
uint8_t h[64], ck[33];
SHA256 ((const uint8_t *)protocolName, 32, h);
memcpy (ck, h, 32);
// h = SHA256(h || rs)
memcpy (h + 32, rs, 32);
SHA256 (h, 64, h);
// h = SHA256(h || pub)
memcpy (h + 32, pub, 32);
SHA256 (h, 64, h);
// x25519 between rs and priv
uint8_t inputKeyMaterial[32];
BN_CTX * ctx = BN_CTX_new ();
i2p::crypto::GetEd25519 ()->Mul (rs, m_ExpandedPrivateKey, inputKeyMaterial, ctx); // rs*priv
BN_CTX_free (ctx);
// temp_key = HMAC-SHA256(ck, input_key_material)
uint8_t tempKey[32]; unsigned int len;
HMAC(EVP_sha256(), ck, 32, inputKeyMaterial, 32, tempKey, &len);
// ck = HMAC-SHA256(temp_key, byte(0x01))
inputKeyMaterial[0] = 1;
HMAC(EVP_sha256(), tempKey, 32, inputKeyMaterial, 1, ck, &len);
// derived = HMAC-SHA256(temp_key, ck || byte(0x02))
ck[32] = 2;
HMAC(EVP_sha256(), tempKey, 32, ck, 33, derived, &len);
return true;
}
void NTCP2Session::CreateEphemeralKey (uint8_t * pub)
{
uint8_t key[32];