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Code Issues Releases Activity

DH auth for encrypted LeaseSet2

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orignal 2019-06-11 10:40:53 -04:00
parent 089a60ded6
commit 74e8610ec9
3 changed files with 60 additions and 21 deletions
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15
libi2pd/Crypto.cpp
View File

@ -296,11 +296,20 @@ namespace crypto
#if OPENSSL_X25519
m_Pkey = EVP_PKEY_new_raw_private_key (EVP_PKEY_X25519, NULL, priv, 32);
m_Ctx = EVP_PKEY_CTX_new (m_Pkey, NULL);
memcpy (m_PublicKey, pub, 32); // TODO: verify against m_Pkey
if (pub)
memcpy (m_PublicKey, pub, 32); // TODO: verify against m_Pkey
else
{
size_t len = 32;
EVP_PKEY_get_raw_public_key (m_Pkey, m_PublicKey, &len);
}
#else
m_Ctx = BN_CTX_new ();
memcpy (m_PrivateKey, priv, 32);
memcpy (m_PublicKey, pub, 32);
m_Ctx = BN_CTX_new ();
if (pub)
memcpy (m_PublicKey, pub, 32);
else
GetEd25519 ()->ScalarMulB (m_PrivateKey, m_PublicKey, m_Ctx);
#endif
}

2
libi2pd/Crypto.h
View File

@ -74,7 +74,7 @@ namespace crypto
public:
X25519Keys ();
X25519Keys (const uint8_t * priv, const uint8_t * pub); // for RouterContext
X25519Keys (const uint8_t * priv, const uint8_t * pub); // if pub is null, derive from priv
~X25519Keys ();
void GenerateKeys ();

64
libi2pd/LeaseSet.cpp
View File

@ -531,20 +531,63 @@ namespace data
}
}
// helper for ExtractClientAuthData
static inline bool GetAuthCookie (const uint8_t * authClients, int numClients, const uint8_t * okm, uint8_t * authCookie)
{
// try to find clientCookie_i for clientID_i = okm[44:51]
for (int i = 0; i < numClients; i++)
{
if (!memcmp (okm + 44, authClients + i*40, 8)) // clientID_i
{
// clientKey_i = okm[0:31]
// clientIV_i = okm[32:43]
i2p::crypto::ChaCha20 (authClients + i*40 + 8, 32, okm, okm + 32, authCookie); // clientCookie_i
return true;
}
}
return false;
}
size_t LeaseSet2::ExtractClientAuthData (const uint8_t * buf, size_t len, const uint8_t * secret, const uint8_t * subcredential, uint8_t * authCookie) const
{
size_t offset = 0;
uint8_t flag = buf[offset]; offset++; // flag
if (flag & 0x01) // client auth
{
if (flag & 0x02) // PSK, bit 1 is set to 1
if (!(flag & 0x0E)) // DH, bit 1-3 all zeroes
{
const uint8_t * ephemeralPublicKey = buf + offset; offset += 32; // ephemeralPublicKey
uint16_t numClients = bufbe16toh (buf + offset); offset += 2; // clients
const uint8_t * authClients = buf + offset; offset += numClients*40; // authClients
if (offset > len)
{
LogPrint (eLogError, "LeaseSet2: Too many clients ", numClients, " in DH auth data");
return 0;
}
// calculate authCookie
if (secret)
{
i2p::crypto::X25519Keys ck (secret, nullptr); // derive cpk_i from csk_i
uint8_t authInput[100];
ck.Agree (ephemeralPublicKey, authInput); // sharedSecret is first 32 bytes of authInput
memcpy (authInput + 32, ck.GetPublicKey (), 32); // cpk_i
memcpy (authInput + 32, subcredential, 36);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (ephemeralPublicKey, authInput, 100, "ELS2_XCA", okm);
if (!GetAuthCookie (authClients, numClients, okm, authCookie))
LogPrint (eLogError, "LeaseSet2: Client cookie DH not found");
}
else
LogPrint (eLogError, "LeaseSet2: Can't calculate authCookie: csk_i is not provided");
}
else if (flag & 0x02) // PSK, bit 1 is set to 1
{
const uint8_t * authSalt = buf + offset; offset += 32; // authSalt
uint16_t numClients = bufbe16toh (buf + offset); offset += 2; // clients
const uint8_t * authClients = buf + offset; offset += numClients*40; // authClients
if (offset > len)
{
LogPrint (eLogError, "LeaseSet2: Too many clients ", numClients, " in auth data");
LogPrint (eLogError, "LeaseSet2: Too many clients ", numClients, " in PSK auth data");
return 0;
}
// calculate authCookie
@ -555,21 +598,8 @@ namespace data
memcpy (authInput + 32, subcredential, 36);
uint8_t okm[64]; // 52 actual data
i2p::crypto::HKDF (authSalt, authInput, 68, "ELS2PSKA", okm);
// try to find clientCookie_i for clientID_i = okm[44:51]
bool found = false;
for (int i = 0; i < numClients; i++)
{
if (!memcmp (okm + 44, authClients + i*40, 8)) // clientID_i
{
// clientKey_i = okm[0:31]
// clientIV_i = okm[32:43]
i2p::crypto::ChaCha20 (authClients + i*40 + 8, 32, okm, okm + 32, authCookie); // clientCookie_i
found = true;
break;
}
}
if (!found)
LogPrint (eLogError, "LeaseSet2: Client cookie not found");
if (!GetAuthCookie (authClients, numClients, okm, authCookie))
LogPrint (eLogError, "LeaseSet2: Client cookie PSK not found");
}
else
LogPrint (eLogError, "LeaseSet2: Can't calculate authCookie: psk_i is not provided");