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0e52100400
Because the algorithm to use is decided already when creating an EVP_PKEY_CTX regardless of how it was created, it turns out that it's unnecessary to provide the SIGNATURE method explicitly, and rather always have it be fetched implicitly. This means fewer changes for applications that want to use new signature algorithms / implementations. Reviewed-by: Matt Caswell <matt@openssl.org> (Merged from https://github.com/openssl/openssl/pull/10303)
121 lines
3.6 KiB
Plaintext
121 lines
3.6 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY_sign_init, EVP_PKEY_sign
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- sign using a public key algorithm
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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int EVP_PKEY_sign_init(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_sign(EVP_PKEY_CTX *ctx,
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unsigned char *sig, size_t *siglen,
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const unsigned char *tbs, size_t tbslen);
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=head1 DESCRIPTION
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EVP_PKEY_sign_init() initializes a public key algorithm context I<ctx> for
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signing using the algorithm given when the context was created
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using L<EVP_PKEY_CTX_new(3)> or variants thereof. The algorithm is used to
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fetch a B<EVP_SIGNATURE> method implicitly, see L<provider(7)/Implicit fetch>
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for more information about implict fetches.
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The EVP_PKEY_sign() function performs a public key signing operation
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using I<ctx>. The data to be signed is specified using the I<tbs> and
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I<tbslen> parameters. If I<sig> is NULL then the maximum size of the output
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buffer is written to the I<siglen> parameter. If I<sig> is not NULL then
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before the call the I<siglen> parameter should contain the length of the
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I<sig> buffer, if the call is successful the signature is written to
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I<sig> and the amount of data written to I<siglen>.
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=head1 NOTES
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EVP_PKEY_sign() does not hash the data to be signed, and therefore is
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normally used to sign digests. For signing arbitrary messages, see the
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L<EVP_DigestSignInit(3)> and
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L<EVP_SignInit(3)> signing interfaces instead.
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After the call to EVP_PKEY_sign_init() algorithm specific control
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operations can be performed to set any appropriate parameters for the
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operation (see L<EVP_PKEY_CTX_ctrl(3)>).
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The function EVP_PKEY_sign() can be called more than once on the same
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context if several operations are performed using the same parameters.
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=head1 RETURN VALUES
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EVP_PKEY_sign_init() and EVP_PKEY_sign() return 1 for success and 0
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or a negative value for failure. In particular a return value of -2
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indicates the operation is not supported by the public key algorithm.
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=head1 EXAMPLES
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Sign data using RSA with PKCS#1 padding and SHA256 digest:
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#include <openssl/evp.h>
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#include <openssl/rsa.h>
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EVP_PKEY_CTX *ctx;
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/* md is a SHA-256 digest in this example. */
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unsigned char *md, *sig;
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size_t mdlen = 32, siglen;
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EVP_PKEY *signing_key;
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/*
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* NB: assumes signing_key and md are set up before the next
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* step. signing_key must be an RSA private key and md must
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* point to the SHA-256 digest to be signed.
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*/
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ctx = EVP_PKEY_CTX_new(signing_key, NULL /* no engine */);
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if (!ctx)
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/* Error occurred */
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if (EVP_PKEY_sign_init(ctx) <= 0)
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/* Error */
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if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
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/* Error */
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if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
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/* Error */
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/* Determine buffer length */
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if (EVP_PKEY_sign(ctx, NULL, &siglen, md, mdlen) <= 0)
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/* Error */
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sig = OPENSSL_malloc(siglen);
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if (!sig)
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/* malloc failure */
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if (EVP_PKEY_sign(ctx, sig, &siglen, md, mdlen) <= 0)
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/* Error */
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/* Signature is siglen bytes written to buffer sig */
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=head1 SEE ALSO
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L<EVP_PKEY_CTX_new(3)>,
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L<EVP_PKEY_CTX_ctrl(3)>,
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L<EVP_PKEY_encrypt(3)>,
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L<EVP_PKEY_decrypt(3)>,
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L<EVP_PKEY_verify(3)>,
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L<EVP_PKEY_verify_recover(3)>,
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L<EVP_PKEY_derive(3)>
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=head1 HISTORY
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EVP_PKEY_sign_init_ex() was added in OpenSSL 3.0.
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These functions were added in OpenSSL 1.0.0.
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=head1 COPYRIGHT
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Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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