diff options
Diffstat (limited to 'ecdsa.c')
| -rw-r--r-- | ecdsa.c | 121 |
1 files changed, 116 insertions, 5 deletions
@@ -237,6 +237,22 @@ static const ecdsa_curve_t * const get_curve(const hal_curve_name_t curve) } } +static inline const ecdsa_curve_t * oid_to_curve(hal_curve_name_t *curve_name, + const uint8_t * const oid, + const size_t oid_len) +{ + assert(curve_name != NULL && oid != NULL); + + const ecdsa_curve_t *curve = NULL; + *curve_name = HAL_CURVE_NONE; + + while ((curve = get_curve(++*curve_name)) != NULL) + if (oid_len == curve->oid_len && memcmp(oid, curve->oid, oid_len) == 0) + return curve; + + return NULL; +} + /* * Finite field operations (hence "ff_"). These are basically just * the usual bignum operations, constrained by the field modulus. @@ -1192,7 +1208,7 @@ hal_error_t hal_ecdsa_private_key_to_der(const hal_ecdsa_key_t * const key, * take if encoded as DER. */ -size_t hal_ecdsa_key_to_der_len(const hal_ecdsa_key_t * const key) +size_t hal_ecdsa_private_key_to_der_len(const hal_ecdsa_key_t * const key) { size_t len; return hal_ecdsa_private_key_to_der(key, NULL, &len, 0) == HAL_OK ? len : 0; @@ -1248,10 +1264,7 @@ hal_error_t hal_ecdsa_private_key_from_der(hal_ecdsa_key_t **key_, if ((err = hal_asn1_decode_header(ASN1_OBJECT_IDENTIFIER, d, vlen, &hlen, &vlen)) != HAL_OK) return err; d += hlen; - for (key->curve = HAL_CURVE_NONE; (curve = get_curve(++key->curve)) != NULL; ) - if (vlen == curve->oid_len && memcmp(d, curve->oid, vlen) == 0) - break; - if (curve == NULL) + if ((curve = oid_to_curve(&key->curve, d, vlen)) == NULL) lose(HAL_ERROR_ASN1_PARSE_FAILED); d += vlen; @@ -1284,6 +1297,104 @@ hal_error_t hal_ecdsa_private_key_from_der(hal_ecdsa_key_t **key_, } /* + * Write public key in SubjectPublicKeyInfo format, see RFCS 5280 and 5480. + */ + +static const uint8_t oid_ecPublicKey[] = { 0x2A, 0x86, 0x48, 0xCE, 0x3D, 0x02, 0x01 }; + +hal_error_t hal_ecdsa_public_key_to_der(const hal_ecdsa_key_t * const key, + uint8_t *der, size_t *der_len, const size_t der_max) +{ + if (key == NULL || (key->type != HAL_KEY_TYPE_EC_PRIVATE && + key->type != HAL_KEY_TYPE_EC_PUBLIC)) + return HAL_ERROR_BAD_ARGUMENTS; + + const ecdsa_curve_t * const curve = get_curve(key->curve); + if (curve == NULL) + return HAL_ERROR_IMPOSSIBLE; + + const size_t q_len = fp_unsigned_bin_size(unconst_fp_int(curve->q)); + const size_t Qx_len = fp_unsigned_bin_size(unconst_fp_int(key->Q->x)); + const size_t Qy_len = fp_unsigned_bin_size(unconst_fp_int(key->Q->y)); + const size_t ecpoint_len = q_len * 2 + 1; + assert(q_len >= Qx_len && q_len >= Qy_len); + + if (der != NULL && ecpoint_len < der_max) { + memset(der, 0, ecpoint_len); + + uint8_t *d = der; + *d++ = 0x04; /* Uncompressed */ + + fp_to_unsigned_bin(unconst_fp_int(key->Q->x), d + q_len - Qx_len); + d += q_len; + + fp_to_unsigned_bin(unconst_fp_int(key->Q->y), d + q_len - Qy_len); + d += q_len; + + assert(d < der + der_max); + } + + return hal_asn1_encode_spki(oid_ecPublicKey, sizeof(oid_ecPublicKey), + curve->oid, curve->oid_len, + der, ecpoint_len, + der, der_len, der_max); +} + +/* + * Convenience wrapper to return how many bytes a public key would + * take if encoded as DER. + */ + +size_t hal_ecdsa_public_key_to_der_len(const hal_ecdsa_key_t * const key) +{ + size_t len; + return hal_ecdsa_public_key_to_der(key, NULL, &len, 0) == HAL_OK ? len : 0; +} + +/* + * Read public key in SubjectPublicKeyInfo format, see RFCS 5280 and 5480. + */ + +hal_error_t hal_ecdsa_public_key_from_der(hal_ecdsa_key_t **key_, + void *keybuf, const size_t keybuf_len, + const uint8_t * const der, const size_t der_len) +{ + hal_ecdsa_key_t *key = keybuf; + + if (key_ == NULL || key == NULL || keybuf_len < sizeof(*key)) + return HAL_ERROR_BAD_ARGUMENTS; + + memset(keybuf, 0, keybuf_len); + key->type = HAL_KEY_TYPE_EC_PUBLIC; + + const uint8_t *alg_oid = NULL, *curve_oid = NULL, *pubkey = NULL; + size_t alg_oid_len, curve_oid_len, pubkey_len; + const ecdsa_curve_t *curve; + hal_error_t err; + + if ((err = hal_asn1_decode_spki(&alg_oid, &alg_oid_len, &curve_oid, &curve_oid_len, &pubkey, &pubkey_len, + der, der_len)) != HAL_OK) + return err; + + if (alg_oid == NULL || curve_oid == NULL || pubkey == NULL || + alg_oid_len != sizeof(oid_ecPublicKey) || memcmp(alg_oid, oid_ecPublicKey, alg_oid_len) != 0 || + (curve = oid_to_curve(&key->curve, curve_oid, curve_oid_len)) == NULL || + pubkey_len < 3 || (pubkey_len & 1) == 0 || pubkey[0] != 0x04 || + pubkey_len / 2 != fp_unsigned_bin_size(unconst_fp_int(curve->q))) + return HAL_ERROR_ASN1_PARSE_FAILED; + + const uint8_t * const Qx = pubkey + 1; + const uint8_t * const Qy = Qx + pubkey_len / 2; + + fp_read_unsigned_bin(key->Q->x, unconst_uint8_t(Qx), pubkey_len / 2); + fp_read_unsigned_bin(key->Q->y, unconst_uint8_t(Qy), pubkey_len / 2); + fp_set(key->Q->z, 1); + + *key_ = key; + return HAL_OK; +} + +/* * Encode a signature in PKCS #11 format: an octet string consisting * of concatenated values for r and s, each padded (if necessary) out * to the byte length of the order of the base point. |