int goldilocks_derive_private_key ( struct goldilocks_private_key_t *privkey, const unsigned char proto[GOLDI_SYMKEY_BYTES] ) { if (!goldilocks_check_init()) { return GOLDI_EUNINIT; } memcpy(&privkey->opaque[2*GOLDI_FIELD_BYTES], proto, GOLDI_SYMKEY_BYTES); unsigned char skb[SHA512_OUTPUT_BYTES]; word_t sk[GOLDI_FIELD_WORDS]; assert(sizeof(skb) >= sizeof(sk)); struct sha512_ctx_t ctx; struct tw_extensible_t exta; struct field_t pk; sha512_init(&ctx); sha512_update(&ctx, (const unsigned char *)"derivepk", GOLDI_DIVERSIFY_BYTES); sha512_update(&ctx, proto, GOLDI_SYMKEY_BYTES); sha512_final(&ctx, (unsigned char *)skb); barrett_deserialize_and_reduce(sk, skb, SHA512_OUTPUT_BYTES, &curve_prime_order); barrett_serialize(privkey->opaque, sk, GOLDI_FIELD_BYTES); scalarmul_fixed_base(&exta, sk, GOLDI_SCALAR_BITS, &goldilocks_global.fixed_base); untwist_and_double_and_serialize(&pk, &exta); field_serialize(&privkey->opaque[GOLDI_FIELD_BYTES], &pk); return GOLDI_EOK; }
static void field_print( const char *descr, const field_a_t a ) { int j; unsigned char ser[FIELD_BYTES]; field_serialize(ser,a); printf("%s = 0x", descr); for (j=FIELD_BYTES - 1; j>=0; j--) { printf("%02x", ser[j]); } printf("\n"); }
int goldilocks_private_to_public ( struct goldilocks_public_key_t *pubkey, const struct goldilocks_private_key_t *privkey ) { struct field_t pk; mask_t msucc = field_deserialize(&pk,&privkey->opaque[GOLDI_FIELD_BYTES]); if (msucc) { field_serialize(pubkey->opaque, &pk); return GOLDI_EOK; } else { return GOLDI_ECORRUPT; } }
/* * fieldset_serialize * * Serializes a field-set. Field-sets are namereflists that * point to the equivalent of individual field declarations, * so those individual fields must be serialized as part of * saving the set. */ static int fieldset_serialize (void *vctx, name_t *np, void *fh) { namereflist_t *frefs = name_extraspace(np); uint16_t n = (uint16_t)namereflist_length(frefs); nameref_t *fld; if (name_serialize(np, fh, &n, sizeof(n))) { for (fld = namereflist_head(frefs); fld != 0; fld = fld->tq_next) { if (field_serialize(vctx, fld->np, fh) == 0) return 0; } } return 1; } /* fieldset_serialize */
int goldilocks_sign ( uint8_t signature_out[GOLDI_SIGNATURE_BYTES], const uint8_t *message, uint64_t message_len, const struct goldilocks_private_key_t *privkey ) { if (!goldilocks_check_init()) { return GOLDI_EUNINIT; } /* challenge = H(pk, [nonceG], message). */ word_t skw[GOLDI_FIELD_WORDS]; mask_t succ = barrett_deserialize(skw,privkey->opaque,&curve_prime_order); if (!succ) { really_memset(skw,0,sizeof(skw)); return GOLDI_ECORRUPT; } /* Derive a nonce. TODO: use HMAC. FUTURE: factor. */ unsigned char sha_out[SHA512_OUTPUT_BYTES]; word_t tk[GOLDI_FIELD_WORDS]; struct sha512_ctx_t ctx; sha512_init(&ctx); sha512_update(&ctx, (const unsigned char *)"signonce", 8); sha512_update(&ctx, &privkey->opaque[2*GOLDI_FIELD_BYTES], GOLDI_SYMKEY_BYTES); sha512_update(&ctx, message, message_len); sha512_update(&ctx, &privkey->opaque[2*GOLDI_FIELD_BYTES], GOLDI_SYMKEY_BYTES); sha512_final(&ctx, sha_out); barrett_deserialize_and_reduce(tk, sha_out, SHA512_OUTPUT_BYTES, &curve_prime_order); /* 4[nonce]G */ uint8_t signature_tmp[GOLDI_FIELD_BYTES]; struct tw_extensible_t exta; struct field_t gsk; scalarmul_fixed_base(&exta, tk, GOLDI_SCALAR_BITS, &goldilocks_global.fixed_base); double_tw_extensible(&exta); untwist_and_double_and_serialize(&gsk, &exta); field_serialize(signature_tmp, &gsk); word_t challenge[GOLDI_FIELD_WORDS]; goldilocks_derive_challenge ( challenge, &privkey->opaque[GOLDI_FIELD_BYTES], signature_tmp, message, message_len ); /* reduce challenge and sub. */ barrett_negate(challenge,GOLDI_FIELD_WORDS,&curve_prime_order); barrett_mac( tk,GOLDI_FIELD_WORDS, challenge,GOLDI_FIELD_WORDS, skw,GOLDI_FIELD_WORDS, &curve_prime_order ); word_t carry = add_nr_ext_packed(tk,tk,GOLDI_FIELD_WORDS,tk,GOLDI_FIELD_WORDS,-1); barrett_reduce(tk,GOLDI_FIELD_WORDS,carry,&curve_prime_order); memcpy(signature_out, signature_tmp, GOLDI_FIELD_BYTES); barrett_serialize(signature_out+GOLDI_FIELD_BYTES, tk, GOLDI_FIELD_BYTES); really_memset((unsigned char *)tk,0,sizeof(tk)); really_memset((unsigned char *)skw,0,sizeof(skw)); really_memset((unsigned char *)challenge,0,sizeof(challenge)); /* response = 2(nonce_secret - sk*challenge) * Nonce = 8[nonce_secret]*G * PK = 2[sk]*G, except doubled (TODO) * so [2] ( [response]G + 2[challenge]PK ) = Nonce */ return 0; }
static int goldilocks_shared_secret_core ( uint8_t shared[GOLDI_SHARED_SECRET_BYTES], const struct goldilocks_private_key_t *my_privkey, const struct goldilocks_public_key_t *your_pubkey, const struct goldilocks_precomputed_public_key_t *pre ) { /* This function doesn't actually need anything in goldilocks_global, * so it doesn't check init. */ assert(GOLDI_SHARED_SECRET_BYTES == SHA512_OUTPUT_BYTES); word_t sk[GOLDI_FIELD_WORDS]; struct field_t pk; mask_t succ = field_deserialize(&pk,your_pubkey->opaque), msucc = -1; #ifdef EXPERIMENT_ECDH_STIR_IN_PUBKEYS struct field_t sum, prod; msucc &= field_deserialize(&sum,&my_privkey->opaque[GOLDI_FIELD_BYTES]); field_mul(&prod,&pk,&sum); field_add(&sum,&pk,&sum); #endif msucc &= barrett_deserialize(sk,my_privkey->opaque,&curve_prime_order); #if GOLDI_IMPLEMENT_PRECOMPUTED_KEYS if (pre) { struct tw_extensible_t tw; succ &= scalarmul_fixed_base(&tw, sk, GOLDI_SCALAR_BITS, &pre->table); untwist_and_double_and_serialize(&pk, &tw); } else { succ &= montgomery_ladder(&pk,&pk,sk,GOLDI_SCALAR_BITS,1); } #else (void)pre; succ &= montgomery_ladder(&pk,&pk,sk,GOLDI_SCALAR_BITS,1); #endif field_serialize(shared,&pk); /* obliterate records of our failure by adjusting with obliteration key */ struct sha512_ctx_t ctx; sha512_init(&ctx); #ifdef EXPERIMENT_ECDH_OBLITERATE_CT uint8_t oblit[GOLDI_DIVERSIFY_BYTES + GOLDI_SYMKEY_BYTES]; unsigned i; for (i=0; i<GOLDI_DIVERSIFY_BYTES; i++) { oblit[i] = "noshared"[i] & ~(succ&msucc); } for (i=0; i<GOLDI_SYMKEY_BYTES; i++) { oblit[GOLDI_DIVERSIFY_BYTES+i] = my_privkey->opaque[2*GOLDI_FIELD_BYTES+i] & ~(succ&msucc); } sha512_update(&ctx, oblit, sizeof(oblit)); #endif #ifdef EXPERIMENT_ECDH_STIR_IN_PUBKEYS /* stir in the sum and product of the pubkeys. */ uint8_t a_pk[GOLDI_FIELD_BYTES]; field_serialize(a_pk, &sum); sha512_update(&ctx, a_pk, GOLDI_FIELD_BYTES); field_serialize(a_pk, &prod); sha512_update(&ctx, a_pk, GOLDI_FIELD_BYTES); #endif /* stir in the shared key and finish */ sha512_update(&ctx, shared, GOLDI_FIELD_BYTES); sha512_final(&ctx, shared); return (GOLDI_ECORRUPT & ~msucc) | (GOLDI_EINVAL & msucc &~ succ) | (GOLDI_EOK & msucc & succ); }