NAME

       X509_verify, X509_self_signed, X509_REQ_verify_ex, X509_REQ_verify, X509_CRL_verify -
       verify certificate, certificate request, or CRL signature

SYNOPSIS

        #include <openssl/x509.h>

        int X509_verify(X509 *x, EVP_PKEY *pkey);
        int X509_self_signed(X509 *cert, int verify_signature);

        int X509_REQ_verify_ex(X509_REQ *a, EVP_PKEY *pkey, OSSL_LIB_CTX *libctx,
                               const char *propq);
        int X509_REQ_verify(X509_REQ *a, EVP_PKEY *r);
        int X509_CRL_verify(X509_CRL *a, EVP_PKEY *r);

DESCRIPTION

       X509_verify() verifies the signature of certificate x using public key pkey. Only the
       signature is checked: no other checks (such as certificate chain validity) are performed.

       X509_self_signed() checks whether certificate cert is self-signed.  For success the issuer
       and subject names must match, the components of the authority key identifier (if present)
       must match the subject key identifier etc.  The signature itself is actually verified only
       if verify_signature is 1, as for explicitly trusted certificates this verification is not
       worth the effort.

       X509_REQ_verify_ex(), X509_REQ_verify() and X509_CRL_verify() verify the signatures of
       certificate requests and CRLs, respectively.

RETURN VALUES

       X509_verify(), X509_REQ_verify_ex(), X509_REQ_verify() and X509_CRL_verify() return 1 if
       the signature is valid and 0 if the signature check fails.  If the signature could not be
       checked at all because it was ill-formed, the certificate or the request was not complete
       or some other error occurred then -1 is returned.

       X509_self_signed() returns the same values but also returns 1 if all respective fields
       match and verify_signature is 0.

SEE ALSO

       d2i_X509(3), ERR_get_error(3), X509_CRL_get0_by_serial(3), X509_get0_signature(3),
       X509_get_ext_d2i(3), X509_get_extension_flags(3), X509_get_pubkey(3),
       X509_get_subject_name(3), X509_get_version(3), X509_NAME_ENTRY_get_object(3),
       X509_NAME_get_index_by_NID(3), X509_NAME_print_ex(3), X509V3_get_d2i(3),
       X509_verify_cert(3), OSSL_LIB_CTX(3)

HISTORY

       The X509_verify(), X509_REQ_verify(), and X509_CRL_verify() functions are available in all
       versions of OpenSSL.

       X509_REQ_verify_ex(), and X509_self_signed() were added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.