freebsd-skq/secure/lib/libcrypto/man/EVP_PKEY_sign.3
jkim 754bee5776 Merge OpenSSL 1.0.1e.
Approved by:	secteam (simon), benl (silence)
2013-02-13 23:07:20 +00:00

219 lines
6.7 KiB
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.\" ========================================================================
.\"
.IX Title "EVP_PKEY_sign 3"
.TH EVP_PKEY_sign 3 "2013-02-11" "1.0.1e" "OpenSSL"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
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.nh
.SH "NAME"
EVP_PKEY_sign_init, EVP_PKEY_sign \- sign using a public key algorithm
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/evp.h>
\&
\& int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
\& int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
\& unsigned char *sig, size_t *siglen,
\& const unsigned char *tbs, size_t tbslen);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fIEVP_PKEY_sign_init()\fR function initializes a public key algorithm
context using key \fBpkey\fR for a signing operation.
.PP
The \fIEVP_PKEY_sign()\fR function performs a public key signing operation
using \fBctx\fR. The data to be signed is specified using the \fBtbs\fR and
\&\fBtbslen\fR parameters. If \fBsig\fR is \fB\s-1NULL\s0\fR then the maximum size of the output
buffer is written to the \fBsiglen\fR parameter. If \fBsig\fR is not \fB\s-1NULL\s0\fR then
before the call the \fBsiglen\fR parameter should contain the length of the
\&\fBsig\fR buffer, if the call is successful the signature is written to
\&\fBsig\fR and the amount of data written to \fBsiglen\fR.
.SH "NOTES"
.IX Header "NOTES"
After the call to \fIEVP_PKEY_sign_init()\fR algorithm specific control
operations can be performed to set any appropriate parameters for the
operation.
.PP
The function \fIEVP_PKEY_sign()\fR can be called more than once on the same
context if several operations are performed using the same parameters.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIEVP_PKEY_sign_init()\fR and \fIEVP_PKEY_sign()\fR return 1 for success and 0
or a negative value for failure. In particular a return value of \-2
indicates the operation is not supported by the public key algorithm.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Sign data using \s-1RSA\s0 with PKCS#1 padding and \s-1SHA256\s0 digest:
.PP
.Vb 2
\& #include <openssl/evp.h>
\& #include <openssl/rsa.h>
\&
\& EVP_PKEY_CTX *ctx;
\& unsigned char *md, *sig;
\& size_t mdlen, siglen;
\& EVP_PKEY *signing_key;
\& /* NB: assumes signing_key, md and mdlen are already set up
\& * and that signing_key is an RSA private key
\& */
\& ctx = EVP_PKEY_CTX_new(signing_key);
\& if (!ctx)
\& /* Error occurred */
\& if (EVP_PKEY_sign_init(ctx) <= 0)
\& /* Error */
\& if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
\& /* Error */
\& if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
\& /* Error */
\&
\& /* Determine buffer length */
\& if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
\& /* Error */
\&
\& sig = OPENSSL_malloc(siglen);
\&
\& if (!sig)
\& /* malloc failure */
\&
\& if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
\& /* Error */
\&
\& /* Signature is siglen bytes written to buffer sig */
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIEVP_PKEY_CTX_new\fR\|(3),
\&\fIEVP_PKEY_encrypt\fR\|(3),
\&\fIEVP_PKEY_decrypt\fR\|(3),
\&\fIEVP_PKEY_verify\fR\|(3),
\&\fIEVP_PKEY_verify_recover\fR\|(3),
\&\fIEVP_PKEY_derive\fR\|(3)
.SH "HISTORY"
.IX Header "HISTORY"
These functions were first added to OpenSSL 1.0.0.