commit e3af3afd5ac4cd40f1e561bd8fbad545d5495770
author Hanno Becker <hanno.becker@arm.com> Wed Sep 13 11:59:26 2017 +0100
committer Hanno Becker <hanno.becker@arm.com> Wed Oct 04 14:34:02 2017 +0100
tree cabffb1493ba8e2ed8c0d9ae450bcf297f62a4e9
parent a89dbd168e7998906aaf6d6fed89d5121d26c380

Omit version from X.509 v1 certificates

The version field in an X.509 certificate is optional and defaults to v1, so it
may be omitted in this case.

library/x509write_crt.c

diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index 363851e..c807533 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -390,16 +390,21 @@
     /*
      *  Version  ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
      */
-    sub_len = 0;
-    MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
-    len += sub_len;
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
-    MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
-                                                    MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+
+    /* Can be omitted for v1 */
+    if( ctx->version > 0 )
+    {
+        sub_len = 0;
+        MBEDTLS_ASN1_CHK_ADD( sub_len, mbedtls_asn1_write_int( &c, tmp_buf, ctx->version ) );
+        len += sub_len;
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, sub_len ) );
+        MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONTEXT_SPECIFIC |
+                                                           MBEDTLS_ASN1_CONSTRUCTED | 0 ) );
+    }
 
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &c, tmp_buf, len ) );
     MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &c, tmp_buf, MBEDTLS_ASN1_CONSTRUCTED |
-                                                    MBEDTLS_ASN1_SEQUENCE ) );
+                                                       MBEDTLS_ASN1_SEQUENCE ) );
 
     /*
      * Make signature