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      1 
      2 #include <string.h>
      3 
      4 #include "crypto_hash_sha512.h"
      5 #include "crypto_scalarmult_curve25519.h"
      6 #include "crypto_sign_ed25519.h"
      7 #include "sign_ed25519_ref10.h"
      8 #include "private/ed25519_ref10.h"
      9 #include "randombytes.h"
     10 #include "utils.h"
     11 
     12 int
     13 crypto_sign_ed25519_seed_keypair(unsigned char *pk, unsigned char *sk,
     14                                  const unsigned char *seed)
     15 {
     16     ge25519_p3 A;
     17 
     18 #ifdef ED25519_NONDETERMINISTIC
     19     memmove(sk, seed, 32);
     20 #else
     21     crypto_hash_sha512(sk, seed, 32);
     22 #endif
     23     sk[0] &= 248;
     24     sk[31] &= 127;
     25     sk[31] |= 64;
     26 
     27     ge25519_scalarmult_base(&A, sk);
     28     ge25519_p3_tobytes(pk, &A);
     29 
     30     memmove(sk, seed, 32);
     31     memmove(sk + 32, pk, 32);
     32 
     33     return 0;
     34 }
     35 
     36 int
     37 crypto_sign_ed25519_keypair(unsigned char *pk, unsigned char *sk)
     38 {
     39     unsigned char seed[32];
     40     int           ret;
     41 
     42     randombytes_buf(seed, sizeof seed);
     43     ret = crypto_sign_ed25519_seed_keypair(pk, sk, seed);
     44     sodium_memzero(seed, sizeof seed);
     45 
     46     return ret;
     47 }
     48 
     49 int
     50 crypto_sign_ed25519_pk_to_curve25519(unsigned char *curve25519_pk,
     51                                      const unsigned char *ed25519_pk)
     52 {
     53     ge25519_p3 A;
     54     fe25519    x;
     55     fe25519    one_minus_y;
     56 
     57     if (ge25519_has_small_order(ed25519_pk) != 0 ||
     58         ge25519_frombytes_negate_vartime(&A, ed25519_pk) != 0 ||
     59         ge25519_is_on_main_subgroup(&A) == 0) {
     60         return -1;
     61     }
     62     fe25519_1(one_minus_y);
     63     fe25519_sub(one_minus_y, one_minus_y, A.Y);
     64     fe25519_invert(one_minus_y, one_minus_y);
     65     fe25519_1(x);
     66     fe25519_add(x, x, A.Y);
     67     fe25519_mul(x, x, one_minus_y);
     68     fe25519_tobytes(curve25519_pk, x);
     69 
     70     return 0;
     71 }
     72 
     73 int
     74 crypto_sign_ed25519_sk_to_curve25519(unsigned char *curve25519_sk,
     75                                      const unsigned char *ed25519_sk)
     76 {
     77     unsigned char h[crypto_hash_sha512_BYTES];
     78 
     79 #ifdef ED25519_NONDETERMINISTIC
     80     memcpy(h, ed25519_sk, 32);
     81 #else
     82     crypto_hash_sha512(h, ed25519_sk, 32);
     83 #endif
     84     h[0] &= 248;
     85     h[31] &= 127;
     86     h[31] |= 64;
     87     memcpy(curve25519_sk, h, crypto_scalarmult_curve25519_BYTES);
     88     sodium_memzero(h, sizeof h);
     89 
     90     return 0;
     91 }
     92