NAME

       X509_sign, X509_sign_ctx, X509_verify, X509_REQ_sign, X509_REQ_sign_ctx, X509_REQ_verify,
       X509_CRL_sign, X509_CRL_sign_ctx, X509_CRL_verify - sign or verify certificate,
       certificate request or CRL signature

SYNOPSIS

        #include <openssl/x509.h>

        int X509_sign(X509 *x, EVP_PKEY *pkey, const EVP_MD *md);
        int X509_sign_ctx(X509 *x, EVP_MD_CTX *ctx);
        int X509_verify(X509 *a, EVP_PKEY *r);

        int X509_REQ_sign(X509_REQ *x, EVP_PKEY *pkey, const EVP_MD *md);
        int X509_REQ_sign_ctx(X509_REQ *x, EVP_MD_CTX *ctx);
        int X509_REQ_verify(X509_REQ *a, EVP_PKEY *r);

        int X509_CRL_sign(X509_CRL *x, EVP_PKEY *pkey, const EVP_MD *md);
        int X509_CRL_sign_ctx(X509_CRL *x, EVP_MD_CTX *ctx);
        int X509_CRL_verify(X509_CRL *a, EVP_PKEY *r);

DESCRIPTION

       X509_sign() signs certificate x using private key pkey and message digest md and sets the
       signature in x. X509_sign_ctx() also signs certificate x but uses the parameters contained
       in digest context ctx.

       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_REQ_sign(), X509_REQ_sign_ctx(), X509_REQ_verify(), X509_CRL_sign(),
       X509_CRL_sign_ctx() and X509_CRL_verify() sign and verify certificate requests and CRLs
       respectively.

NOTES

       X509_sign_ctx() is used where the default parameters for the corresponding public key and
       digest are not suitable. It can be used to sign keys using RSA-PSS for example.

       For efficiency reasons and to work around ASN.1 encoding issues the encoding of the signed
       portion of a certificate, certificate request and CRL is cached internally. If the signed
       portion of the structure is modified the encoding is not always updated meaning a stale
       version is sometimes used. This is not normally a problem because modifying the signed
       portion will invalidate the signature and signing will always update the encoding.

RETURN VALUES

       X509_sign(), X509_sign_ctx(), X509_REQ_sign(), X509_REQ_sign_ctx(), X509_CRL_sign() and
       X509_CRL_sign_ctx() return the size of the signature in bytes for success and zero for
       failure.

       X509_verify(), 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 invalid or some other error occurred then -1 is returned.

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_add_entry_by_txt(3),
       X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3), X509_NAME_print_ex(3),
       X509_new(3), X509V3_get_d2i(3), X509_verify_cert(3)

HISTORY

       X509_sign(), X509_REQ_sign() and X509_CRL_sign() are available in all versions of OpenSSL.

       X509_sign_ctx(), X509_REQ_sign_ctx() and X509_CRL_sign_ctx() were first added to OpenSSL
       1.0.1.

COPYRIGHT

       Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (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>.