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use HKDF for NTCP2 key derivation data phase

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orignal 2019-12-18 20:45:47 -05:00
parent 19a88300c6
commit 599ec62bb0
4 changed files with 32 additions and 24 deletions
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30
libi2pd/Crypto.cpp
View file

@ -1259,18 +1259,29 @@ namespace crypto
#endif
}
void HKDF (const uint8_t * salt, const uint8_t * key, size_t keyLen, const std::string& info, uint8_t * out)
void HKDF (const uint8_t * salt, const uint8_t * key, size_t keyLen, const std::string& info,
uint8_t * out, size_t outLen)
{
#if OPENSSL_HKDF
EVP_PKEY_CTX * pctx = EVP_PKEY_CTX_new_id (EVP_PKEY_HKDF, NULL);
EVP_PKEY_CTX * pctx = EVP_PKEY_CTX_new_id (EVP_PKEY_HKDF, nullptr);
EVP_PKEY_derive_init (pctx);
EVP_PKEY_CTX_set_hkdf_md (pctx, EVP_sha256());
EVP_PKEY_CTX_set1_hkdf_salt (pctx, salt, 32);
EVP_PKEY_CTX_set1_hkdf_key (pctx, key, keyLen);
if (key && keyLen)
{
EVP_PKEY_CTX_set1_hkdf_salt (pctx, salt, 32);
EVP_PKEY_CTX_set1_hkdf_key (pctx, key, keyLen);
}
else
{
// zerolen
EVP_PKEY_CTX_hkdf_mode (pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY);
uint8_t tempKey[32]; unsigned int len;
HMAC(EVP_sha256(), salt, 32, nullptr, 0, tempKey, &len);
EVP_PKEY_CTX_set1_hkdf_key (pctx, tempKey, len);
}
if (info.length () > 0)
EVP_PKEY_CTX_add1_hkdf_info (pctx, info.c_str (), info.length ());
size_t outlen = 64;
EVP_PKEY_derive (pctx, out, &outlen);
EVP_PKEY_derive (pctx, out, &outLen);
EVP_PKEY_CTX_free (pctx);
#else
uint8_t prk[32]; unsigned int len;
@ -1278,8 +1289,11 @@ namespace crypto
auto l = info.length ();
memcpy (out, info.c_str (), l); out[l] = 0x01;
HMAC(EVP_sha256(), prk, 32, out, l + 1, out, &len);
memcpy (out + 32, info.c_str (), l); out[l + 32] = 0x02;
HMAC(EVP_sha256(), prk, 32, out, l + 33, out + 32, &len);
if (outLen > 32) // 64
{
memcpy (out + 32, info.c_str (), l); out[l + 32] = 0x02;
HMAC(EVP_sha256(), prk, 32, out, l + 33, out + 32, &len);
}
#endif
}

2
libi2pd/Crypto.h
View file

@ -296,7 +296,7 @@ namespace crypto
// HKDF
void HKDF (const uint8_t * salt, const uint8_t * key, size_t keyLen, const std::string& info, uint8_t * out); // salt - 32, out - 64, info <= 32
void HKDF (const uint8_t * salt, const uint8_t * key, size_t keyLen, const std::string& info, uint8_t * out, size_t outLen = 64); // salt - 32, out - 32 or 64, info <= 32
// init and terminate
void InitCrypto (bool precomputation);

22
libi2pd/NTCP2.cpp
View file

@ -441,23 +441,17 @@ namespace transport
void NTCP2Session::KeyDerivationFunctionDataPhase ()
{
uint8_t tempKey[32]; unsigned int len;
HMAC(EVP_sha256(), m_Establisher->GetCK (), 32, nullptr, 0, tempKey, &len); // temp_key = HMAC-SHA256(ck, zerolen)
static uint8_t one[1] = { 1 };
HMAC(EVP_sha256(), tempKey, 32, one, 1, m_Kab, &len); // k_ab = HMAC-SHA256(temp_key, byte(0x01)).
m_Kab[32] = 2;
HMAC(EVP_sha256(), tempKey, 32, m_Kab, 33, m_Kba, &len); // k_ba = HMAC-SHA256(temp_key, k_ab || byte(0x02))
static uint8_t ask[4] = { 'a', 's', 'k', 1 }, master[32];
HMAC(EVP_sha256(), tempKey, 32, ask, 4, master, &len); // ask_master = HMAC-SHA256(temp_key, "ask" || byte(0x01))
uint8_t k[64];
i2p::crypto::HKDF (m_Establisher->GetCK (), nullptr, 0, "", k); // k_ab, k_ba = HKDF(ck, zerolen)
memcpy (m_Kab, k, 32); memcpy (m_Kba, k + 32, 32);
uint8_t master[32];
i2p::crypto::HKDF (m_Establisher->GetCK (), nullptr, 0, "ask", master, 32); // ask_master = HKDF(ck, zerolen, info="ask")
uint8_t h[39];
memcpy (h, m_Establisher->GetH (), 32);
memcpy (h + 32, "siphash", 7);
HMAC(EVP_sha256(), master, 32, h, 39, tempKey, &len); // temp_key = HMAC-SHA256(ask_master, h || "siphash")
HMAC(EVP_sha256(), tempKey, 32, one, 1, master, &len); // sip_master = HMAC-SHA256(temp_key, byte(0x01))
HMAC(EVP_sha256(), master, 32, nullptr, 0, tempKey, &len); // temp_key = HMAC-SHA256(sip_master, zerolen)
HMAC(EVP_sha256(), tempKey, 32, one, 1, m_Sipkeysab, &len); // sipkeys_ab = HMAC-SHA256(temp_key, byte(0x01)).
m_Sipkeysab[32] = 2;
HMAC(EVP_sha256(), tempKey, 32, m_Sipkeysab, 33, m_Sipkeysba, &len); // sipkeys_ba = HMAC-SHA256(temp_key, sipkeys_ab || byte(0x02))
i2p::crypto::HKDF (master, h, 39, "", master, 32); // sip_master = HKDF(ask_master, h || "siphash")
i2p::crypto::HKDF (master, nullptr, 0, "", k, 64); // sipkeys_ab, sipkeys_ba = HKDF(sip_master, zerolen)
memcpy (m_Sipkeysab, k, 32); memcpy (m_Sipkeysba, k + 32, 32);
}

2
libi2pd/NTCP2.h
View file

@ -195,7 +195,7 @@ namespace transport
std::unique_ptr<NTCP2Establisher> m_Establisher;
// data phase
uint8_t m_Kab[33], m_Kba[32], m_Sipkeysab[33], m_Sipkeysba[32];
uint8_t m_Kab[32], m_Kba[32], m_Sipkeysab[32], m_Sipkeysba[32];
const uint8_t * m_SendKey, * m_ReceiveKey;
#if OPENSSL_SIPHASH
EVP_PKEY * m_SendSipKey, * m_ReceiveSipKey;