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/*
* Ed25519
* (C) 2017 Ribose Inc
*
* Based on the public domain code from SUPERCOP ref10 by
* Peter Schwabe, Daniel J. Bernstein, Niels Duif, Tanja Lange, Bo-Yin Yang
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/ed25519.h>
#include <botan/internal/ed25519_internal.h>
#include <botan/sha2_64.h>
namespace Botan {
void ed25519_gen_keypair(uint8_t* pk, uint8_t* sk, const uint8_t seed[32])
{
uint8_t az[64];
SHA_512 sha;
sha.update(seed, 32);
sha.final(az);
az[0] &= 248;
az[31] &= 63;
az[31] |= 64;
ge_scalarmult_base(pk, az);
// todo copy_mem
memmove(sk, seed, 32);
memmove(sk + 32, pk, 32);
}
void ed25519_sign(uint8_t sig[64],
const uint8_t* m, size_t mlen,
const uint8_t* sk)
{
uint8_t az[64];
uint8_t nonce[64];
uint8_t hram[64];
SHA_512 sha;
sha.update(sk, 32);
sha.final(az);
az[0] &= 248;
az[31] &= 63;
az[31] |= 64;
sha.update(az + 32, 32);
sha.update(m, mlen);
sha.final(nonce);
sc_reduce(nonce);
ge_scalarmult_base(sig, nonce);
sha.update(sig, 32);
sha.update(sk + 32, 32);
sha.update(m, mlen);
sha.final(hram);
sc_reduce(hram);
sc_muladd(sig + 32, hram, az, nonce);
}
bool ed25519_verify(const uint8_t* m, size_t mlen,
const uint8_t sig[64],
const uint8_t* pk)
{
uint8_t h[64];
uint8_t rcheck[32];
ge_p3 A;
SHA_512 sha;
if(sig[63] & 224)
{
return false;
}
if(ge_frombytes_negate_vartime(&A, pk) != 0)
{
return false;
}
sha.update(sig, 32);
sha.update(pk, 32);
sha.update(m, mlen);
sha.final(h);
sc_reduce(h);
ge_double_scalarmult_vartime(rcheck, h, &A, sig + 32);
return constant_time_compare(rcheck, sig, 32);
}
}
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