.\" $OpenBSD: X509_get0_signature.3,v 1.9 2024/08/28 07:18:55 tb Exp $ .\" selective merge up to: .\" OpenSSL man3/X509_get0_signature 2f7a2520 Apr 25 17:28:08 2017 +0100 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2020 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .\" The original file was written by Dr. Stephen Henson . .\" Copyright (c) 2015 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: August 28 2024 $ .Dt X509_GET0_SIGNATURE 3 .Os .Sh NAME .Nm X509_get0_signature , .Nm X509_REQ_get0_signature , .Nm X509_CRL_get0_signature , .Nm X509_get0_tbs_sigalg , .Nm X509_CRL_get0_tbs_sigalg , .Nm X509_get_signature_type , .Nm X509_get_signature_nid , .Nm X509_REQ_get_signature_nid , .Nm X509_CRL_get_signature_nid , .Nm X509_get_signature_info .Nd signature information .Sh SYNOPSIS .In openssl/x509.h .Ft void .Fo X509_get0_signature .Fa "const ASN1_BIT_STRING **psig" .Fa "const X509_ALGOR **palg" .Fa "const X509 *x" .Fc .Ft void .Fo X509_REQ_get0_signature .Fa "const X509_REQ *req" .Fa "const ASN1_BIT_STRING **psig" .Fa "const X509_ALGOR **palg" .Fc .Ft void .Fo X509_CRL_get0_signature .Fa "const X509_CRL *crl" .Fa "const ASN1_BIT_STRING **psig" .Fa "const X509_ALGOR **palg" .Fc .Ft const X509_ALGOR * .Fo X509_get0_tbs_sigalg .Fa "const X509 *x" .Fc .Ft const X509_ALGOR * .Fo X509_CRL_get0_tbs_sigalg .Fa "const X509_CRL *crl" .Fc .Ft int .Fo X509_get_signature_type .Fa "const X509 *x" .Fc .Ft int .Fo X509_get_signature_nid .Fa "const X509 *x" .Fc .Ft int .Fo X509_REQ_get_signature_nid .Fa "const X509_REQ *req" .Fc .Ft int .Fo X509_CRL_get_signature_nid .Fa "const X509_CRL *crl" .Fc .Ft int .Fo X509_get_signature_info .Fa "X509 *x" .Fa "int *md_nid" .Fa "int *pkey_nid" .Fa "int *security_bits" .Fa "uint32_t *flags" .Fc .Sh DESCRIPTION .Fn X509_get0_signature , .Fn X509_REQ_get0_signature , and .Fn X509_CRL_get0_signature set .Pf * Fa psig to the signature and .Pf * Fa palg to the signature algorithm of .Fa x , .Fa req , or .Fa crl , respectively. .Fn X509_get0_tbs_sigalg and .Fn X509_CRL_get0_tbs_sigalg return the signature algorithm in the signed portion of .Fa x or .Fa crl , respectively. The values returned are internal pointers that must not be freed by the caller. .Pp .Fn X509_get_signature_type returns the base NID corresponding to the signature algorithm of .Fa x just like .Xr EVP_PKEY_base_id 3 does. .Pp .Fn X509_get_signature_nid , .Fn X509_REQ_get_signature_nid , and .Fn X509_CRL_get_signature_nid return the NID corresponding to the signature algorithm of .Fa x , .Fa req , or .Fa crl , respectively, just like .Xr EVP_PKEY_id 3 does. .Pp .Fn X509_get_signature_info retrieves information about the signature of certificate .Fa x . The NID of the digest algorithm is written to .Pf * Fa md_nid , the public key algorithm to .Pf * Fa pkey_nid , the effective security bits to .Pf * Fa security_bits , and flag details to .Pf * Fa flags . Any of the output parameters can be set to .Dv NULL if the information is not required. If .Fa flags is not a .Dv NULL pointer, .Pf * Fa flags is set to the bitwise OR of: .Bl -tag -width 1n -offset 3n .It Dv X509_SIG_INFO_VALID No error occurred. This flag is set if .Fn X509_get_signature_info returns 1. .It Dv X509_SIG_INFO_TLS The signature algorithm is appropriate for use in TLS. For a supported EdDSA algorithm (in LibreSSL this is Ed25519) this flag is always set. For an RSASSA-PSS PSS algorithm this flag is set if the parameters are DER encoded, the digest algorithm is one of SHA256, SHA384, or SHA512, the same digest algorithm is used in the mask generation function, and the salt length is equal to the digest algorithm's output length. For all other signature algorithms this flag is set if the digest algorithm is one of SHA1, SHA256, SHA384, or SHA512. .El .Pp .Fn X509_get_signature_info returns 1 on success and 0 on failure. Failure conditions include unsupported signature algorithms, certificate parsing errors and memory allocation failure. .Pp These functions provide lower level access to the signature for cases where an application wishes to analyse or generate a signature in a form where .Xr X509_sign 3 is not appropriate, for example in a non-standard or unsupported format. .Sh SEE ALSO .Xr EVP_PKEY_base_id 3 , .Xr OBJ_obj2nid 3 , .Xr X509_ALGOR_new 3 , .Xr X509_CRL_get0_by_serial 3 , .Xr X509_CRL_new 3 , .Xr X509_get_pubkey 3 , .Xr X509_get_subject_name 3 , .Xr X509_get_version 3 , .Xr X509_new 3 , .Xr X509_REQ_new 3 , .Xr X509_sign 3 , .Xr X509_signature_dump 3 , .Xr X509_verify_cert 3 .Sh HISTORY .Fn X509_get_signature_type first appeared in SSLeay 0.8.0 and has been available since .Ox 2.4 . .Pp .Fn X509_get0_signature and .Fn X509_get_signature_nid first appeared in OpenSSL 1.0.2. .Fn X509_REQ_get0_signature , .Fn X509_CRL_get0_signature , .Fn X509_get0_tbs_sigalg , .Fn X509_REQ_get_signature_nid , and .Fn X509_CRL_get_signature_nid first appeared in OpenSSL 1.1.0. All these functions have been available since .Ox 6.3 . .Pp .Fn X509_CRL_get0_tbs_sigalg first appeared in LibreSSL 3.7.1 and has been available since .Ox 7.3 . .Pp .Fn X509_get_signature_info first appeared in OpenSSL 1.1.1 and has been available since .Ox 7.6 . .Sh CAVEATS The security bits returned by .Fn X509_get_signature_info refer to the information available from the certificate signature (such as the signing digest). In some cases the actual security of the signature is smaller because the signing key is less secure. For example in a certificate signed using SHA512 and a 1024-bit RSA key.