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-rw-r--r--asn1.c163
1 files changed, 163 insertions, 0 deletions
diff --git a/asn1.c b/asn1.c
index 0794537..3786cbd 100644
--- a/asn1.c
+++ b/asn1.c
@@ -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: