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#include <string.h>
#include "api.h"
#include "crypto_hash_sha512.h"
#include "crypto_scalarmult_curve25519.h"
#include "randombytes.h"
#include "utils.h"
#include "fe.h"
#include "ge.h"
int crypto_sign_seed_keypair(unsigned char *pk, unsigned char *sk,
const unsigned char *seed)
{
ge_p3 A;
crypto_hash_sha512(sk,seed,32);
sk[0] &= 248;
sk[31] &= 63;
sk[31] |= 64;
ge_scalarmult_base(&A,sk);
ge_p3_tobytes(pk,&A);
memmove(sk, seed, 32);
memmove(sk + 32, pk, 32);
return 0;
}
int crypto_sign_keypair(unsigned char *pk, unsigned char *sk)
{
unsigned char seed[32];
int ret;
randombytes_buf(seed, sizeof seed);
ret = crypto_sign_seed_keypair(pk, sk, seed);
sodium_memzero(seed, sizeof seed);
return ret;
}
int crypto_sign_ed25519_pk_to_curve25519(unsigned char *curve25519_pk,
const unsigned char *ed25519_pk)
{
ge_p3 A;
fe x;
fe one_minus_y;
if (ge_frombytes_negate_vartime(&A, ed25519_pk) != 0) {
return -1;
}
fe_1(one_minus_y);
fe_sub(one_minus_y, one_minus_y, A.Y);
fe_invert(one_minus_y, one_minus_y);
fe_1(x);
fe_add(x, x, A.Y);
fe_mul(x, x, one_minus_y);
fe_tobytes(curve25519_pk, x);
return 0;
}
int crypto_sign_ed25519_sk_to_curve25519(unsigned char *curve25519_sk,
const unsigned char *ed25519_sk)
{
unsigned char h[crypto_hash_sha512_BYTES];
crypto_hash_sha512(h, ed25519_sk,
crypto_sign_ed25519_SECRETKEYBYTES -
crypto_sign_ed25519_PUBLICKEYBYTES);
h[0] &= 248;
h[31] &= 127;
h[31] |= 64;
memcpy(curve25519_sk, h, crypto_scalarmult_curve25519_BYTES);
sodium_memzero(h, sizeof h);
return 0;
}
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