Fixed AlgorithmIdentifier parameters when used with ECDSA signature algorithm in x509 certificate
Signed-off-by: Marek Jansta <jansta@2n.cz>
diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index a8f4c28..e994411 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -342,6 +342,7 @@
size_t sub_len = 0, pub_len = 0, sig_and_oid_len = 0, sig_len;
size_t len = 0;
mbedtls_pk_type_t pk_alg;
+ int write_sig_null_par;
/*
* Prepare data to be signed at the end of the target buffer
@@ -433,9 +434,20 @@
/*
* Signature ::= AlgorithmIdentifier
*/
+ if (pk_alg == MBEDTLS_PK_ECDSA) {
+ /*
+ * The AlgorithmIdentifier's parameters field must be absent for DSA/ECDSA signature
+ * algorithms, see https://www.rfc-editor.org/rfc/rfc5480#page-17 and
+ * https://www.rfc-editor.org/rfc/rfc5758#section-3.
+ */
+ write_sig_null_par = 0;
+ } else {
+ write_sig_null_par = 1;
+ }
MBEDTLS_ASN1_CHK_ADD(len,
- mbedtls_asn1_write_algorithm_identifier(&c, buf,
- sig_oid, strlen(sig_oid), 0));
+ mbedtls_asn1_write_algorithm_identifier_ext(&c, buf,
+ sig_oid, strlen(sig_oid),
+ 0, write_sig_null_par));
/*
* Serial ::= INTEGER
@@ -492,8 +504,8 @@
* into the CRT buffer. */
c2 = buf + size;
MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len, mbedtls_x509_write_sig(&c2, c,
- sig_oid, sig_oid_len, sig,
- sig_len));
+ sig_oid, sig_oid_len,
+ sig, sig_len, pk_alg));
/*
* Memory layout after this step: