server2-sha256.crt had the issuer ON and CN encoded as UTF8String, but the
corresponding CA certificate test-ca_cat12.crt had them encoded as
PrintableString. The strings matched, which is sufficient according to RFC
5280 §7.1 and RFC 4518 §2.1. However, GnuTLS 3.4.10 requires the strings to
have the same encoding, so it did not accept that the
UTF8String "PolarSSL Test CA" certificate was signed by the
PrintableString "PolarSSL Test CA" CA.
Since Mbed TLS 2.14 (specifically ebc1f40aa0
merged via https://github.com/ARMmbed/mbedtls/pull/1641), server2-sha256.crt
is generated by Mbed TLS's own cert_write program, which emits a
PrintableString. In older versions, this file was generated by OpenSSL,
which started emitting UTF8String at some point.
4f928c0f37 merged via
https://github.com/ARMmbed/mbedtls/pull/2418 fixed this for the SHA-1
certificate which was used at the time. The present commit applies the same
fix for the SHA-256 certificate that is now in use.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
