52 lines
1.2 KiB
C
52 lines
1.2 KiB
C
#include <string.h>
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#include "crypto_sign.h"
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#include "crypto_hash_sha512.h"
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#include "ge25519.h"
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int crypto_sign(
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unsigned char *sm,unsigned long long *smlen,
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const unsigned char *m,unsigned long long mlen,
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const unsigned char *sk
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)
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{
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unsigned char pk[32];
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unsigned char nonce[64];
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unsigned char hram[64];
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sc25519 sck, scs, scsk;
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ge25519 ger;
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/* sk: 32-byte scalar a, 32-byte randomizer z */
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crypto_sign_pubkey(pk,sk);
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/* pk: 32-byte public key A */
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*smlen = mlen + 64;
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memmove(sm + 64,m,mlen);
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memmove(sm + 32,sk + 32,32);
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/* sm: 32-byte uninit, 32-byte z, mlen-byte m */
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crypto_hash_sha512(nonce, sm+32, mlen+32);
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/* nonce: 64-byte H(z,m) */
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sc25519_from64bytes(&sck, nonce);
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ge25519_scalarmult_base(&ger, &sck);
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ge25519_pack(sm, &ger);
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/* sm: 32-byte R, 32-byte z, mlen-byte m */
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memmove(sm + 32,pk,32);
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/* sm: 32-byte R, 32-byte A, mlen-byte m */
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crypto_hash_sha512(hram,sm,mlen + 64);
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/* hram: 64-byte H(R,A,m) */
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sc25519_from64bytes(&scs, hram);
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sc25519_from32bytes(&scsk, sk);
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sc25519_mul(&scs, &scs, &scsk);
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sc25519_add(&scs, &scs, &sck);
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/* scs: S = nonce + H(R,A,m)a */
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sc25519_to32bytes(sm + 32,&scs);
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/* sm: 32-byte R, 32-byte S, mlen-byte m */
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return 0;
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}
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