[gnutls-devel] GnuTLS | Name Constraints applied to intermediate CA CN because CA certificate does not have Extended key usage ( (#776)

Development of GNU's TLS library gnutls-devel at lists.gnutls.org
Thu May 30 00:15:27 CEST 2019

I debugged gnutls-cli. It does work as expected.

pidgin validates each certificate pair individually (gnutls_x509_crt_verify) while gnutls-cli does the same using a list of certificates (gnutls_certificate_verify_peers). The difference is that while calling gnutls_x509_crt_verify directly, the end_cert parameter in verify_crt is always 1, even while testing an intermediate CA against Root CA. So, intermediate CA is treated as a Server Certificate. So, indeed pidgin bug.

Anyway, gnutls should not check name constraints against a CN value that cannot be a DNS name. OpenSSL does check that situation: https://github.com/openssl/openssl/commit/d02d80b2e80adfdde49f76cf7c7af4e013f45005#diff-caf502a9d3e53f3b21e77e5e324b62b4

Reply to this email directly or view it on GitLab: https://gitlab.com/gnutls/gnutls/issues/776#note_176032374
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