NAME

       X509_get0_signature, X509_REQ_set0_signature, X509_REQ_set1_signature_algo, X509_get_signature_nid,
       X509_get0_tbs_sigalg, X509_REQ_get0_signature, X509_REQ_get_signature_nid, X509_CRL_get0_signature,
       X509_CRL_get_signature_nid, X509_get_signature_info, X509_SIG_INFO_get, X509_SIG_INFO_set - signature
       information

SYNOPSIS

        #include <openssl/x509.h>

        void X509_get0_signature(const ASN1_BIT_STRING **psig,
                                 const X509_ALGOR **palg,
                                 const X509 *x);
        void X509_REQ_set0_signature(X509_REQ *req, ASN1_BIT_STRING *psig);
        int X509_REQ_set1_signature_algo(X509_REQ *req, X509_ALGOR *palg);
        int X509_get_signature_nid(const X509 *x);
        const X509_ALGOR *X509_get0_tbs_sigalg(const X509 *x);

        void X509_REQ_get0_signature(const X509_REQ *crl,
                                     const ASN1_BIT_STRING **psig,
                                     const X509_ALGOR **palg);
        int X509_REQ_get_signature_nid(const X509_REQ *crl);

        void X509_CRL_get0_signature(const X509_CRL *crl,
                                     const ASN1_BIT_STRING **psig,
                                     const X509_ALGOR **palg);
        int X509_CRL_get_signature_nid(const X509_CRL *crl);

        int X509_get_signature_info(X509 *x, int *mdnid, int *pknid, int *secbits,
                                    uint32_t *flags);

        int X509_SIG_INFO_get(const X509_SIG_INFO *siginf, int *mdnid, int *pknid,
                             int *secbits, uint32_t *flags);
        void X509_SIG_INFO_set(X509_SIG_INFO *siginf, int mdnid, int pknid,
                               int secbits, uint32_t flags);

DESCRIPTION

       X509_get0_signature() sets *psig to the signature of x and *palg to the signature algorithm of x. The
       values returned are internal pointers which MUST NOT be freed up after the call.

       X509_set0_signature() and X509_REQ_set1_signature_algo() are the equivalent setters for the two values of
       X509_get0_signature().

       X509_get0_tbs_sigalg() returns the signature algorithm in the signed portion of x.

       X509_get_signature_nid() returns the NID corresponding to the signature algorithm of x.

       X509_REQ_get0_signature(), X509_REQ_get_signature_nid() X509_CRL_get0_signature() and
       X509_CRL_get_signature_nid() perform the same function for certificate requests and CRLs.

       X509_get_signature_info() retrieves information about the signature of certificate x. The NID of the
       signing digest is written to *mdnid, the public key algorithm to *pknid, the effective security bits to
       *secbits and flag details to *flags. Any of the parameters can be set to NULL if the information is not
       required.

       X509_SIG_INFO_get() and X509_SIG_INFO_set() get and set information about a signature in an X509_SIG_INFO
       structure. They are only used by implementations of algorithms which need to set custom signature
       information: most applications will never need to call them.

NOTES

       These functions provide lower level access to signatures in certificates where an application wishes to
       analyse or generate a signature in a form where X509_sign() et al is not appropriate (for example a non
       standard or unsupported format).

       The security bits returned by X509_get_signature_info() refers to information available from the
       certificate signature (such as the signing digest). In some cases the actual security of the signature is
       less because the signing key is less secure: for example a certificate signed using SHA-512 and a 1024
       bit RSA key.

RETURN VALUES

       X509_get_signature_nid(), X509_REQ_get_signature_nid() and X509_CRL_get_signature_nid() return a NID.

       X509_get0_signature(), X509_REQ_get0_signature() and X509_CRL_get0_signature() do not return values.

       X509_get_signature_info() returns 1 if the signature information returned is valid or 0 if the
       information is not available (e.g.  unknown algorithms or malformed parameters).

       X509_REQ_set1_signature_algo() returns 0 on success; or 1 on an error (e.g. null ALGO pointer).
       X509_REQ_set0_signature does not return an error value.

SEE ALSO

       d2i_X509(3), ERR_get_error(3), X509_CRL_get0_by_serial(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), X509_sign(3), X509V3_get_d2i(3), X509_verify_cert(3)

HISTORY

       The X509_get0_signature() and X509_get_signature_nid() functions were added in OpenSSL 1.0.2.

       The X509_REQ_get0_signature(), X509_REQ_get_signature_nid(), X509_CRL_get0_signature() and
       X509_CRL_get_signature_nid() were added in OpenSSL 1.1.0.

       The X509_REQ_set0_signature() and X509_REQ_set1_signature_algo() were added in OpenSSL 1.1.1e.

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>.

3.0.13                                             2025-09-18                          X509_GET0_SIGNATURE(3SSL)