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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)
109 lines
3.3 KiB
Plaintext
109 lines
3.3 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY_verify_init, EVP_PKEY_verify
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- signature verification 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_verify_init(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
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const 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_verify_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_verify() function performs a public key verification operation
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using I<ctx>. The signature is specified using the I<sig> and
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I<siglen> parameters. The verified data (i.e. the data believed originally
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signed) is specified using the I<tbs> and I<tbslen> parameters.
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=head1 NOTES
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After the call to EVP_PKEY_verify_init() algorithm specific control
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operations can be performed to set any appropriate parameters for the
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operation.
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The function EVP_PKEY_verify() 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_verify_init() and EVP_PKEY_verify() return 1 if the verification was
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successful and 0 if it failed. Unlike other functions the return value 0 from
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EVP_PKEY_verify() only indicates that the signature did not verify
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successfully (that is tbs did not match the original data or the signature was
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of invalid form) it is not an indication of a more serious error.
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A negative value indicates an error other that signature verification failure.
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In particular a return value of -2 indicates the operation is not supported by
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the public key algorithm.
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=head1 EXAMPLES
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Verify signature using PKCS#1 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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unsigned char *md, *sig;
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size_t mdlen, siglen;
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EVP_PKEY *verify_key;
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/*
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* NB: assumes verify_key, sig, siglen md and mdlen are already set up
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* and that verify_key is an RSA public key
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*/
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ctx = EVP_PKEY_CTX_new(verify_key, NULL /* no engine */);
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if (!ctx)
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/* Error occurred */
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if (EVP_PKEY_verify_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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/* Perform operation */
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ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
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/*
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* ret == 1 indicates success, 0 verify failure and < 0 for some
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* other error.
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*/
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=head1 SEE ALSO
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L<EVP_PKEY_CTX_new(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_sign(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_verify_init_ex() was added in OpenSSL 3.0.
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All other functions were added in OpenSSL 1.0.0.
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=head1 COPYRIGHT
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Copyright 2006-2018 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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