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blind public key for encrypted LeaseSet2

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orignal 2019-03-05 15:51:24 -05:00
parent ea3070d02b
commit 32e55ebd0c
4 changed files with 30 additions and 2 deletions
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15
libi2pd/Ed25519.cpp
View file

@ -491,6 +491,21 @@ namespace crypto
}
#endif
void Ed25519::BlindPublicKey (const uint8_t * pub, const uint8_t * seed, uint8_t * blinded)
{
BN_CTX * ctx = BN_CTX_new ();
// calculate alpha = seed mod l
BIGNUM * alpha = DecodeBN<64> (seed); // pub is in Little Endian
BN_mod (alpha, alpha, l, ctx); // % l
uint8_t priv[32];
EncodeBN (alpha, priv, 32); // back to Little Endian
BN_free (alpha);
// A' = BLIND_PUBKEY(A, alpha) = A + DERIVE_PUBLIC(alpha)
auto A1 = Sum (DecodePublicKey (pub, ctx), MulB (priv, ctx), ctx); // pub + B*alpha
EncodePublicKey (A1, blinded, ctx);
BN_CTX_free (ctx);
}
void Ed25519::ExpandPrivateKey (const uint8_t * key, uint8_t * expandedKey)
{
SHA512 (key, EDDSA25519_PRIVATE_KEY_LENGTH, expandedKey);

1
libi2pd/Ed25519.h
View file

@ -80,6 +80,7 @@ namespace crypto
void ScalarMul (const uint8_t * p, const uint8_t * e, uint8_t * buf, BN_CTX * ctx) const; // p is point, e is number for x25519
void ScalarMulB (const uint8_t * e, uint8_t * buf, BN_CTX * ctx) const;
#endif
void BlindPublicKey (const uint8_t * pub, const uint8_t * seed, uint8_t * blinded); // for encrypted LeaseSet2, pub - 32, seed - 64, blinded - 32
bool Verify (const EDDSAPoint& publicKey, const uint8_t * digest, const uint8_t * signature) const;
void Sign (const uint8_t * expandedPrivateKey, const uint8_t * publicKeyEncoded, const uint8_t * buf, size_t len, uint8_t * signature) const;

11
libi2pd/LeaseSet.cpp
View file

@ -3,6 +3,7 @@
#include <openssl/hmac.h>
#include "I2PEndian.h"
#include "Crypto.h"
#include "Ed25519.h"
#include "Log.h"
#include "Timestamp.h"
#include "NetDb.hpp"
@ -532,6 +533,16 @@ namespace data
HMAC(EVP_sha256(), prk, 32, out, 41, out + 32, &len);
}
void LeaseSet2::BlindPublicKey (std::shared_ptr<const IdentityEx> identity, const char * date, SigningKeyType blindedKeyType, uint8_t * blindedKey)
{
uint16_t stA = htobe16 (identity->GetSigningKeyType ()), stA1 = htobe16 (blindedKeyType);
uint8_t salt[32], seed[64];
//seed = HKDF(H("I2PGenerateAlpha", keydata), datestring || secret, "i2pblinding1", 64)
H ("I2PGenerateAlpha", { {identity->GetSigningPublicKeyBuffer (), identity->GetSigningPublicKeyLen ()}, {(const uint8_t *)&stA, 2}, {(const uint8_t *)&stA1, 2} }, salt);
HKDF (salt, { (const uint8_t *)date, 8 }, "i2pblinding1", seed);
i2p::crypto::GetEd25519 ()->BlindPublicKey (identity->GetSigningPublicKeyBuffer (), seed, blindedKey);
}
void LeaseSet2::Encrypt (const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx) const
{
auto encryptor = m_Encryptor; // TODO: atomic

5
libi2pd/LeaseSet.h
View file

@ -155,8 +155,9 @@ namespace data
uint64_t ExtractTimestamp (const uint8_t * buf, size_t len) const;
// for encrypted LS
void H (const std::string& p, const std::vector<std::pair<const uint8_t *, size_t> >& bufs, uint8_t * hash);
void HKDF (const uint8_t * salt, const std::pair<const uint8_t *, size_t>& ikm, const std::string& info, uint8_t * out); // salt - 32, out - 64, info <= 32
static void H (const std::string& p, const std::vector<std::pair<const uint8_t *, size_t> >& bufs, uint8_t * hash);
static void HKDF (const uint8_t * salt, const std::pair<const uint8_t *, size_t>& ikm, const std::string& info, uint8_t * out); // salt - 32, out - 64, info <= 32
static void BlindPublicKey (std::shared_ptr<const IdentityEx> identity, const char * date, SigningKeyType blindedKeyType, uint8_t * blindedKey); // blinded key 32 bytes, date is 8 chars "YYYYMMDD"
private: