| 1 | =pod
|
|---|
| 2 |
|
|---|
| 3 | =head1 NAME
|
|---|
| 4 |
|
|---|
| 5 | EVP_PKEY_sign_init, EVP_PKEY_sign - sign using a public key algorithm
|
|---|
| 6 |
|
|---|
| 7 | =head1 SYNOPSIS
|
|---|
| 8 |
|
|---|
| 9 | #include <openssl/evp.h>
|
|---|
| 10 |
|
|---|
| 11 | int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
|
|---|
| 12 | int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
|
|---|
| 13 | unsigned char *sig, size_t *siglen,
|
|---|
| 14 | const unsigned char *tbs, size_t tbslen);
|
|---|
| 15 |
|
|---|
| 16 | =head1 DESCRIPTION
|
|---|
| 17 |
|
|---|
| 18 | The EVP_PKEY_sign_init() function initializes a public key algorithm
|
|---|
| 19 | context using key B<pkey> for a signing operation.
|
|---|
| 20 |
|
|---|
| 21 | The EVP_PKEY_sign() function performs a public key signing operation
|
|---|
| 22 | using B<ctx>. The data to be signed is specified using the B<tbs> and
|
|---|
| 23 | B<tbslen> parameters. If B<sig> is B<NULL> then the maximum size of the output
|
|---|
| 24 | buffer is written to the B<siglen> parameter. If B<sig> is not B<NULL> then
|
|---|
| 25 | before the call the B<siglen> parameter should contain the length of the
|
|---|
| 26 | B<sig> buffer, if the call is successful the signature is written to
|
|---|
| 27 | B<sig> and the amount of data written to B<siglen>.
|
|---|
| 28 |
|
|---|
| 29 | =head1 NOTES
|
|---|
| 30 |
|
|---|
| 31 | EVP_PKEY_sign() does not hash the data to be signed, and therefore is
|
|---|
| 32 | normally used to sign digests. For signing arbitrary messages, see the
|
|---|
| 33 | L<EVP_DigestSignInit(3)> and
|
|---|
| 34 | L<EVP_SignInit(3)> signing interfaces instead.
|
|---|
| 35 |
|
|---|
| 36 | After the call to EVP_PKEY_sign_init() algorithm specific control
|
|---|
| 37 | operations can be performed to set any appropriate parameters for the
|
|---|
| 38 | operation (see L<EVP_PKEY_CTX_ctrl(3)>).
|
|---|
| 39 |
|
|---|
| 40 | The function EVP_PKEY_sign() can be called more than once on the same
|
|---|
| 41 | context if several operations are performed using the same parameters.
|
|---|
| 42 |
|
|---|
| 43 | =head1 RETURN VALUES
|
|---|
| 44 |
|
|---|
| 45 | EVP_PKEY_sign_init() and EVP_PKEY_sign() return 1 for success and 0
|
|---|
| 46 | or a negative value for failure. In particular a return value of -2
|
|---|
| 47 | indicates the operation is not supported by the public key algorithm.
|
|---|
| 48 |
|
|---|
| 49 | =head1 EXAMPLES
|
|---|
| 50 |
|
|---|
| 51 | Sign data using RSA with PKCS#1 padding and SHA256 digest:
|
|---|
| 52 |
|
|---|
| 53 | #include <openssl/evp.h>
|
|---|
| 54 | #include <openssl/rsa.h>
|
|---|
| 55 |
|
|---|
| 56 | EVP_PKEY_CTX *ctx;
|
|---|
| 57 | /* md is a SHA-256 digest in this example. */
|
|---|
| 58 | unsigned char *md, *sig;
|
|---|
| 59 | size_t mdlen = 32, siglen;
|
|---|
| 60 | EVP_PKEY *signing_key;
|
|---|
| 61 |
|
|---|
| 62 | /*
|
|---|
| 63 | * NB: assumes signing_key and md are set up before the next
|
|---|
| 64 | * step. signing_key must be an RSA private key and md must
|
|---|
| 65 | * point to the SHA-256 digest to be signed.
|
|---|
| 66 | */
|
|---|
| 67 | ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */);
|
|---|
| 68 | if (!ctx)
|
|---|
| 69 | /* Error occurred */
|
|---|
| 70 | if (EVP_PKEY_sign_init(ctx) <= 0)
|
|---|
| 71 | /* Error */
|
|---|
| 72 | if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
|
|---|
| 73 | /* Error */
|
|---|
| 74 | if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
|
|---|
| 75 | /* Error */
|
|---|
| 76 |
|
|---|
| 77 | /* Determine buffer length */
|
|---|
| 78 | if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
|
|---|
| 79 | /* Error */
|
|---|
| 80 |
|
|---|
| 81 | sig = OPENSSL_malloc(siglen);
|
|---|
| 82 |
|
|---|
| 83 | if (!sig)
|
|---|
| 84 | /* malloc failure */
|
|---|
| 85 |
|
|---|
| 86 | if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
|
|---|
| 87 | /* Error */
|
|---|
| 88 |
|
|---|
| 89 | /* Signature is siglen bytes written to buffer sig */
|
|---|
| 90 |
|
|---|
| 91 |
|
|---|
| 92 | =head1 SEE ALSO
|
|---|
| 93 |
|
|---|
| 94 | L<EVP_PKEY_CTX_new(3)>,
|
|---|
| 95 | L<EVP_PKEY_CTX_ctrl(3)>,
|
|---|
| 96 | L<EVP_PKEY_encrypt(3)>,
|
|---|
| 97 | L<EVP_PKEY_decrypt(3)>,
|
|---|
| 98 | L<EVP_PKEY_verify(3)>,
|
|---|
| 99 | L<EVP_PKEY_verify_recover(3)>,
|
|---|
| 100 | L<EVP_PKEY_derive(3)>
|
|---|
| 101 |
|
|---|
| 102 | =head1 HISTORY
|
|---|
| 103 |
|
|---|
| 104 | These functions were added in OpenSSL 1.0.0.
|
|---|
| 105 |
|
|---|
| 106 | =head1 COPYRIGHT
|
|---|
| 107 |
|
|---|
| 108 | Copyright 2006-2019 The OpenSSL Project Authors. All Rights Reserved.
|
|---|
| 109 |
|
|---|
| 110 | Licensed under the OpenSSL license (the "License"). You may not use
|
|---|
| 111 | this file except in compliance with the License. You can obtain a copy
|
|---|
| 112 | in the file LICENSE in the source distribution or at
|
|---|
| 113 | L<https://www.openssl.org/source/license.html>.
|
|---|
| 114 |
|
|---|
| 115 | =cut
|
|---|
