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complete implementation of RedDSA

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orignal 2019-03-24 18:42:52 -04:00
parent c797ac4268
commit ff44bcc489
4 changed files with 100 additions and 7 deletions
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54
libi2pd/Ed25519.cpp
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@ -121,8 +121,8 @@ namespace crypto
return passed;
}
void Ed25519::Sign (const uint8_t * expandedPrivateKey, const uint8_t * publicKeyEncoded, const uint8_t * buf, size_t len,
uint8_t * signature) const
void Ed25519::Sign (const uint8_t * expandedPrivateKey, const uint8_t * publicKeyEncoded,
const uint8_t * buf, size_t len, uint8_t * signature) const
{
BN_CTX * bnCtx = BN_CTX_new ();
// calculate r
@ -153,6 +153,44 @@ namespace crypto
BN_CTX_free (bnCtx);
}
void Ed25519::SignRedDSA (const uint8_t * privateKey, const uint8_t * publicKeyEncoded,
const uint8_t * buf, size_t len, uint8_t * signature) const
{
BN_CTX * bnCtx = BN_CTX_new ();
// T = 80 random bytes
uint8_t T[80];
RAND_bytes (T, 80);
// calculate r = H*(T || publickey || data)
SHA512_CTX ctx;
SHA512_Init (&ctx);
SHA512_Update (&ctx, T, 80);
SHA512_Update (&ctx, publicKeyEncoded, 32);
SHA512_Update (&ctx, buf, len); // data
uint8_t digest[64];
SHA512_Final (digest, &ctx);
BIGNUM * r = DecodeBN<64> (digest);
BN_mod (r, r, l, bnCtx); // % l
EncodeBN (r, digest, 32);
// calculate R
uint8_t R[EDDSA25519_SIGNATURE_LENGTH/2]; // we must use separate buffer because signature might be inside buf
EncodePoint (Normalize (MulB (digest, bnCtx), bnCtx), R);
// calculate S
SHA512_Init (&ctx);
SHA512_Update (&ctx, R, EDDSA25519_SIGNATURE_LENGTH/2); // R
SHA512_Update (&ctx, publicKeyEncoded, EDDSA25519_PUBLIC_KEY_LENGTH); // public key
SHA512_Update (&ctx, buf, len); // data
SHA512_Final (digest, &ctx);
BIGNUM * h = DecodeBN<64> (digest);
// S = (r + h*a) % l
BIGNUM * a = DecodeBN<EDDSA25519_PRIVATE_KEY_LENGTH> (privateKey);
BN_mod_mul (h, h, a, l, bnCtx); // %l
BN_mod_add (h, h, r, l, bnCtx); // %l
memcpy (signature, R, EDDSA25519_SIGNATURE_LENGTH/2);
EncodeBN (h, signature + EDDSA25519_SIGNATURE_LENGTH/2, EDDSA25519_SIGNATURE_LENGTH/2); // S
BN_free (r); BN_free (h); BN_free (a);
BN_CTX_free (bnCtx);
}
EDDSAPoint Ed25519::Sum (const EDDSAPoint& p1, const EDDSAPoint& p2, BN_CTX * ctx) const
{
// x3 = (x1*y2+y1*x2)*(z1*z2-d*t1*t2)
@ -514,6 +552,18 @@ namespace crypto
expandedKey[EDDSA25519_PRIVATE_KEY_LENGTH - 1] |= 0x40; // set second bit
}
void Ed25519::CreateRedDSAPrivateKey (uint8_t * priv)
{
uint8_t seed[32];
RAND_bytes (seed, 32);
BIGNUM * p = DecodeBN<32> (seed);
BN_CTX * ctx = BN_CTX_new ();
BN_mod (p, p, l, ctx); // % l
EncodeBN (p, priv, 32);
BN_CTX_free (ctx);
BN_free (p);
}
static std::unique_ptr<Ed25519> g_Ed25519;
std::unique_ptr<Ed25519>& GetEd25519 ()
{