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.\" ========================================================================
.\"
.IX Title "RSA_SIGN 3"
.TH RSA_SIGN 3 "2023-09-11" "1.1.1w" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
RSA_sign, RSA_verify \- RSA signatures
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/rsa.h>
\&
\& int RSA_sign(int type, const unsigned char *m, unsigned int m_len,
\&              unsigned char *sigret, unsigned int *siglen, RSA *rsa);
\&
\& int RSA_verify(int type, const unsigned char *m, unsigned int m_len,
\&                unsigned char *sigbuf, unsigned int siglen, RSA *rsa);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBRSA_sign()\fR signs the message digest \fBm\fR of size \fBm_len\fR using the
private key \fBrsa\fR using RSASSA\-PKCS1\-v1_5 as specified in \s-1RFC 3447.\s0 It
stores the signature in \fBsigret\fR and the signature size in \fBsiglen\fR.
\&\fBsigret\fR must point to RSA_size(\fBrsa\fR) bytes of memory.
Note that \s-1PKCS\s0 #1 adds meta-data, placing limits on the size of the
key that can be used.
See \fBRSA_private_encrypt\fR\|(3) for lower-level
operations.
.PP
\&\fBtype\fR denotes the message digest algorithm that was used to generate
\&\fBm\fR.
If \fBtype\fR is \fBNID_md5_sha1\fR,
an \s-1SSL\s0 signature (\s-1MD5\s0 and \s-1SHA1\s0 message digests with \s-1PKCS\s0 #1 padding
and no algorithm identifier) is created.
.PP
\&\fBRSA_verify()\fR verifies that the signature \fBsigbuf\fR of size \fBsiglen\fR
matches a given message digest \fBm\fR of size \fBm_len\fR. \fBtype\fR denotes
the message digest algorithm that was used to generate the signature.
\&\fBrsa\fR is the signer's public key.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBRSA_sign()\fR returns 1 on success.
\&\fBRSA_verify()\fR returns 1 on successful verification.
.PP
The error codes can be obtained by \fBERR_get_error\fR\|(3).
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
\&\s-1SSL, PKCS\s0 #1 v2.0
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBERR_get_error\fR\|(3),
\&\fBRSA_private_encrypt\fR\|(3),
\&\fBRSA_public_decrypt\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2016 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.