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<a id="user-content-description-of-problem" class="anchor" href="#description-of-problem" aria-hidden="true"></a>Description of problem:</h2>
<p dir="auto">When calling gnutls_pubkey_verify_data2 with the GNUTLS_VERIFY_DISABLE_CA_SIGN flag set, GNUTLS_E_INVALID_REQUEST is asserted due to an erroneous comparison of the OLD_PUBKEY_VERIFY_FLAG_TLS1_RSA define (previously defined as GNUTLS_PUBKEY_VERIFY_FLAG_TLS1_RSA in gnutls_pubkey_flags_t) with the gnutls_certificate_verify_flags passed to the function.</p>
<p dir="auto">This occurs when the bitwise AND comparison of the gnutls_certificate_verify_flags against OLD_PUBKEY_VERIFY_FLAG_TLS1_RSA returns '1', as the GNUTLS_VERIFY_DISABLE_CA_SIGN gnutls_certificate_verify_flag and the deprecated GNUTLS_PUBKEY_VERIFY_FLAG_TLS1_RSA gnutls_pubkey_flag share the least significant bit of flags.</p>
<p dir="auto">The bug was introduced in version 3.4.2 with this specific commit:
<a href="https://gitlab.com/gnutls/gnutls/commit/0422a67eb0935e1dd96d602445ee179ef9dd993d" data-original="https://gitlab.com/gnutls/gnutls/commit/0422a67eb0935e1dd96d602445ee179ef9dd993d" data-link="false" data-link-reference="true" data-project="179611" data-commit="0422a67eb0935e1dd96d602445ee179ef9dd993d" data-reference-type="commit" data-container="body" data-placement="bottom" title="use the same flags in all verification functions" class="gfm gfm-commit has-tooltip">0422a67e</a></p>
<p dir="auto">I assume the OLD_PUBKEY_VERIFY_FLAG_TLS1_RSA define was added to maintain backwards compatibility with the old calling of gnutls_pubkey_verify_data2 that utilized gnutls_pubkey_flags_t.
Looking at internal gnutls calls of gnutls_pubkey_verify_data2, I don't see any call where this would be necessary any more. Perhaps this comparison is deprecated as well and could be removed?</p>
<p dir="auto">gnutls_pubkey_verify_hash2 has the same comparison and the same issue might be present there as well, though I have not tested this.</p>
<h2 dir="auto">
<a id="user-content-version-of-gnutls-used" class="anchor" href="#version-of-gnutls-used" aria-hidden="true"></a>Version of gnutls used:</h2>
<p dir="auto">Tested in 3.6.7, issue is not present in versions prior to 3.4.2.</p>
<h2 dir="auto">
<a id="user-content-distributor-of-gnutls-eg-ubuntu-fedora-rhel" class="anchor" href="#distributor-of-gnutls-eg-ubuntu-fedora-rhel" aria-hidden="true"></a>Distributor of gnutls (e.g., Ubuntu, Fedora, RHEL)</h2>
<p dir="auto">N/A, built directly from gnutls source.</p>
<h2 dir="auto">
<a id="user-content-how-reproducible" class="anchor" href="#how-reproducible" aria-hidden="true"></a>How reproducible:</h2>
<p dir="auto">Steps to Reproduce:</p>
<ul dir="auto">
<li>Call gnutls_pubkey_verify_data2 with a valid signature and the GNUTLS_VERIFY_DISABLE_CA_SIGN flag set</li>
</ul>
<h2 dir="auto">
<a id="user-content-actual-results" class="anchor" href="#actual-results" aria-hidden="true"></a>Actual results:</h2>
<p dir="auto">gnutls_pubkey_verify_data2 asserts GNUTLS_E_INVALID_REQUEST</p>
<h2 dir="auto">
<a id="user-content-expected-results" class="anchor" href="#expected-results" aria-hidden="true"></a>Expected results:</h2>
<p dir="auto">gnutls_pubkey_verify_data2 returns 0</p>
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