diff options
Diffstat (limited to 'src/ext/ed25519/ref10/blinding.c')
| -rw-r--r-- | src/ext/ed25519/ref10/blinding.c | 49 |
1 files changed, 46 insertions, 3 deletions
diff --git a/src/ext/ed25519/ref10/blinding.c b/src/ext/ed25519/ref10/blinding.c index ee3e8666fa..a3b32fa80c 100644 --- a/src/ext/ed25519/ref10/blinding.c +++ b/src/ext/ed25519/ref10/blinding.c @@ -12,8 +12,8 @@ static void ed25519_ref10_gettweak(unsigned char *out, const unsigned char *param) { - const char str[] = "Derive temporary signing key"; - crypto_hash_sha512_2(out, (const unsigned char*)str, strlen(str), param, 32); + memcpy(out, param, 32); + out[0] &= 248; /* Is this necessary necessary ? */ out[31] &= 63; out[31] |= 64; @@ -49,6 +49,7 @@ int ed25519_ref10_blind_public_key(unsigned char *out, unsigned char pkcopy[32]; ge_p3 A; ge_p2 Aprime; + int retval = -1; ed25519_ref10_gettweak(tweak, param); @@ -62,15 +63,57 @@ int ed25519_ref10_blind_public_key(unsigned char *out, * "ge_frombytes", we'd use that, but there isn't. */ memcpy(pkcopy, inp, 32); pkcopy[31] ^= (1<<7); - ge_frombytes_negate_vartime(&A, pkcopy); + if (ge_frombytes_negate_vartime(&A, pkcopy) != 0) { + goto done; + } /* There isn't a regular ge_scalarmult -- we have to do tweak*A + zero*B. */ ge_double_scalarmult_vartime(&Aprime, tweak, &A, zero); ge_tobytes(out, &Aprime); + retval = 0; + + done: memwipe(tweak, 0, sizeof(tweak)); memwipe(&A, 0, sizeof(A)); memwipe(&Aprime, 0, sizeof(Aprime)); memwipe(pkcopy, 0, sizeof(pkcopy)); + return retval; +} + +/* This is the group order encoded in a format that + * ge_double_scalarmult_vartime() understands. The group order m is: + * m = 2^252 + 27742317777372353535851937790883648493 = + * 0x1000000000000000000000000000000014def9dea2f79cd65812631a5cf5d3ed + */ +static const uint8_t modm_m[32] = {0xed,0xd3,0xf5,0x5c,0x1a,0x63,0x12,0x58, + 0xd6,0x9c,0xf7,0xa2,0xde,0xf9,0xde,0x14, + 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, + 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x10}; + +/* Do the scalar multiplication of <b>pubkey</b> with the group order + * <b>modm_m</b>. Place the result in <b>out</b> which must be at least 32 + * bytes long. */ +int +ed25519_ref10_scalarmult_with_group_order(unsigned char *out, + const unsigned char *pubkey) +{ + unsigned char pkcopy[32]; + unsigned char zero[32] = {0}; + ge_p3 Point; + ge_p2 Result; + + /* All this is done to fit 'pubkey' in 'Point' so that it can be used by + * ed25519 ref code. Same thing as in blinding function */ + memcpy(pkcopy, pubkey, 32); + pkcopy[31] ^= (1<<7); + if (ge_frombytes_negate_vartime(&Point, pkcopy) != 0) { + return -1; /* error: bail out */ + } + + /* There isn't a regular scalarmult -- we have to do r = l*P + 0*B */ + ge_double_scalarmult_vartime(&Result, modm_m, &Point, zero); + ge_tobytes(out, &Result); + return 0; } |