diff options
Diffstat (limited to 'asn1.c')
| -rw-r--r-- | asn1.c | 163 |
1 files changed, 163 insertions, 0 deletions
@@ -153,6 +153,85 @@ hal_error_t hal_asn1_encode_integer(const fp_int * const bn, } /* + * Encode a public key into an RFC 5280 SubjectPublicKeyInfo. + */ + +hal_error_t hal_asn1_encode_spki(const uint8_t * const alg_oid, const size_t alg_oid_len, + const uint8_t * const curve_oid, const size_t curve_oid_len, + const uint8_t * const pubkey, const size_t pubkey_len, + uint8_t *der, size_t *der_len, const size_t der_max) +{ + if (alg_oid == NULL || alg_oid_len == 0 || pubkey == NULL || pubkey_len == 0 || (curve_oid == NULL && curve_oid_len != 0)) + return HAL_ERROR_BAD_ARGUMENTS; + + const uint8_t curve_oid_tag = curve_oid == NULL ? ASN1_NULL : ASN1_OBJECT_IDENTIFIER; + + hal_error_t err; + + size_t hlen, hlen_spki, hlen_algid, hlen_alg, hlen_curve, hlen_bit; + + if ((err = hal_asn1_encode_header(ASN1_OBJECT_IDENTIFIER, alg_oid_len, NULL, &hlen_alg, 0)) != HAL_OK || + (err = hal_asn1_encode_header(curve_oid_tag, curve_oid_len, NULL, &hlen_curve, 0)) != HAL_OK || + (err = hal_asn1_encode_header(ASN1_BIT_STRING, pubkey_len, NULL, &hlen_bit, 0)) != HAL_OK) + return err; + + const size_t algid_len = hlen_alg + alg_oid_len + hlen_curve + curve_oid_len; + + if ((err = hal_asn1_encode_header(ASN1_SEQUENCE, algid_len, NULL, &hlen_algid, 0)) != HAL_OK) + return err; + + const size_t vlen = hlen_algid + hlen_alg + alg_oid_len + hlen_curve + curve_oid_len + hlen_bit + pubkey_len; + + if ((err = hal_asn1_encode_header(ASN1_SEQUENCE, vlen, NULL, &hlen_spki, 0)) != HAL_OK) + return err; + + /* + * Handle pubkey early, in case it was staged into our output buffer. + */ + if (der != NULL && hlen_spki + vlen <= der_max) + memmove(der + hlen_spki + vlen - pubkey_len, pubkey, pubkey_len); + + err = hal_asn1_encode_header(ASN1_SEQUENCE, vlen, der, &hlen, der_max); + + if (der_len != NULL) + *der_len = hlen + vlen; + + if (der == NULL || err != HAL_OK) + return err; + + uint8_t *d = der + hlen; + memset(d, 0, vlen); + + if ((err = hal_asn1_encode_header(ASN1_SEQUENCE, algid_len, d, &hlen, der + der_max - d)) != HAL_OK) + return err; + d += hlen; + + if ((err = hal_asn1_encode_header(ASN1_OBJECT_IDENTIFIER, alg_oid_len, d, &hlen, der + der_max - d)) != HAL_OK) + return err; + d += hlen; + memcpy(d, alg_oid, alg_oid_len); + d += alg_oid_len; + + if ((err = hal_asn1_encode_header(curve_oid_tag, curve_oid_len, d, &hlen, der + der_max - d)) != HAL_OK) + return err; + d += hlen; + if (curve_oid != NULL) + memcpy(d, curve_oid, curve_oid_len); + d += curve_oid_len; + + if ((err = hal_asn1_encode_header(ASN1_BIT_STRING, pubkey_len, d, &hlen, der + der_max - d)) != HAL_OK) + return err; + d += hlen; + + d += pubkey_len; /* pubkey handled early, above. */ + + assert(d == der + hlen_spki + vlen); + assert(d <= der + der_max); + + return HAL_OK; +} + +/* * Parse tag and length of an ASN.1 object. Tag must match value * specified by the caller. On success, sets hlen and vlen to lengths * of header and value, respectively. @@ -219,6 +298,90 @@ hal_error_t hal_asn1_decode_integer(fp_int *bn, } /* + * Decode a public key from an RFC 5280 SubjectPublicKeyInfo. + */ + +hal_error_t hal_asn1_decode_spki(const uint8_t **alg_oid, size_t *alg_oid_len, + const uint8_t **curve_oid, size_t *curve_oid_len, + const uint8_t **pubkey, size_t *pubkey_len, + const uint8_t *const der, const size_t der_len) +{ + if (alg_oid == NULL || alg_oid_len == NULL || curve_oid == NULL || curve_oid_len == NULL || + pubkey == NULL || pubkey_len == NULL || der == NULL) + return HAL_ERROR_BAD_ARGUMENTS; + + size_t hlen, vlen; + hal_error_t err; + + if ((err = hal_asn1_decode_header(ASN1_SEQUENCE, der, der_len, &hlen, &vlen)) != HAL_OK) + return err; + + const uint8_t * const der_end = der + hlen + vlen; + const uint8_t *d = der + hlen; + + if ((err = hal_asn1_decode_header(ASN1_SEQUENCE, der, der_end - d, &hlen, &vlen)) != HAL_OK) + return err; + d += hlen; + + const uint8_t * const algid_end = d + vlen; + + if ((err = hal_asn1_decode_header(ASN1_OBJECT_IDENTIFIER, d, algid_end - d, &hlen, &vlen)) != HAL_OK) + return err; + d += hlen; + if (vlen > algid_end - d) + return HAL_ERROR_ASN1_PARSE_FAILED; + *alg_oid = d; + *alg_oid_len = vlen; + d += vlen; + + *curve_oid = NULL; + *curve_oid_len = 0; + + if (d < algid_end) { + switch (*d) { + + case ASN1_OBJECT_IDENTIFIER: + if ((err = hal_asn1_decode_header(ASN1_OBJECT_IDENTIFIER, d, algid_end - d, &hlen, &vlen)) != HAL_OK) + return err; + d += hlen; + if (vlen > algid_end - d) + return HAL_ERROR_ASN1_PARSE_FAILED; + *curve_oid = d; + *curve_oid_len = vlen; + d += vlen; + break; + + case ASN1_NULL: + if ((err = hal_asn1_decode_header(ASN1_NULL, d, algid_end - d, &hlen, &vlen)) != HAL_OK) + return err; + d += hlen; + if (vlen == 0) + break; + + default: + return HAL_ERROR_ASN1_PARSE_FAILED; + } + } + + if (d != algid_end) + return HAL_ERROR_ASN1_PARSE_FAILED; + + if ((err = hal_asn1_decode_header(ASN1_BIT_STRING, d, der_end - d, &hlen, &vlen)) != HAL_OK) + return err; + d += hlen; + if (vlen >= algid_end - d || vlen == 0 || *d != 0x00) + return HAL_ERROR_ASN1_PARSE_FAILED; + *pubkey = ++d; + *pubkey_len = --vlen; + d += vlen; + + if (d != der_end) + return HAL_ERROR_ASN1_PARSE_FAILED; + + return HAL_OK; +} + +/* * Local variables: * indent-tabs-mode: nil * End: |