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X509_verify_cert(3)                 OpenSSL                X509_verify_cert(3)

       X509_verify_cert - discover and verify X509 certificte chain

       libcrypto, -lcrypto

        #include <openssl/x509.h>

        int X509_verify_cert(X509_STORE_CTX *ctx);

       The X509_verify_cert() function attempts to discover and validate a
       certificate chain based on parameters in ctx. A complete description of
       the process is contained in the openssl_verify(1) manual page.

       If a complete chain can be built and validated this function returns 1,
       otherwise it return zero, in exceptional circumstances it can also
       return a negative code.

       If the function fails additional error information can be obtained by
       examining ctx using, for example X509_STORE_CTX_get_error().

       Applications rarely call this function directly but it is used by
       OpenSSL internally for certificate validation, in both the S/MIME and
       SSL/TLS code.

       A negative return value from X509_verify_cert() can occur if it is
       invoked incorrectly, such as with no certificate set in ctx, or when it
       is called twice in succession without reinitialising ctx for the second
       call.  A negative return value can also happen due to internal resource
       problems or if a retry operation is requested during internal lookups
       (which never happens with standard lookup methods).  Applications must
       check for <= 0 return value on error.

       This function uses the header x509.h as opposed to most chain
       verification functiosn which use x509_vfy.h.


       X509_verify_cert() is available in all versions of SSLeay and OpenSSL.

1.0.2k                            2016-10-14               X509_verify_cert(3)