fc5ecaddd0
While stereotyped repetitions are frowned upon in literature, they serve a useful purpose in manual pages, because it is easier for the user to find certain information if it is always presented in the same way. For that reason, this commit harmonizes the varying formulations in the HISTORY section about which functions, flags, etc. were added in which OpenSSL version. It also attempts to make the pod files more grep friendly by avoiding to insert line breaks between the symbol names and the corresponding version number in which they were introduced (wherever possible). Some punctuation and typographical errors were fixed on the way. Reviewed-by: Tim Hudson <tjh@openssl.org> (Merged from https://github.com/openssl/openssl/pull/7854)
103 lines
2.8 KiB
Text
103 lines
2.8 KiB
Text
=pod
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=head1 NAME
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EVP_PKEY_derive_init, EVP_PKEY_derive_set_peer, EVP_PKEY_derive - derive public key algorithm shared secret
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer);
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int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen);
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=head1 DESCRIPTION
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The EVP_PKEY_derive_init() function initializes a public key algorithm
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context using key B<pkey> for shared secret derivation.
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The EVP_PKEY_derive_set_peer() function sets the peer key: this will normally
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be a public key.
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The EVP_PKEY_derive() derives a shared secret using B<ctx>.
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If B<key> is B<NULL> then the maximum size of the output buffer is written to
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the B<keylen> parameter. If B<key> is not B<NULL> then before the call the
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B<keylen> parameter should contain the length of the B<key> buffer, if the call
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is successful the shared secret is written to B<key> and the amount of data
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written to B<keylen>.
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=head1 NOTES
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After the call to EVP_PKEY_derive_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_derive() 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_derive_init() and EVP_PKEY_derive() 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 EXAMPLE
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Derive shared secret (for example DH or EC keys):
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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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ENGINE *eng;
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unsigned char *skey;
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size_t skeylen;
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EVP_PKEY *pkey, *peerkey;
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/* NB: assumes pkey, eng, peerkey have been already set up */
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ctx = EVP_PKEY_CTX_new(pkey, eng);
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if (!ctx)
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/* Error occurred */
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if (EVP_PKEY_derive_init(ctx) <= 0)
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/* Error */
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if (EVP_PKEY_derive_set_peer(ctx, peerkey) <= 0)
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/* Error */
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/* Determine buffer length */
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if (EVP_PKEY_derive(ctx, NULL, &skeylen) <= 0)
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/* Error */
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skey = OPENSSL_malloc(skeylen);
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if (!skey)
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/* malloc failure */
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if (EVP_PKEY_derive(ctx, skey, &skeylen) <= 0)
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/* Error */
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/* Shared secret is skey bytes written to buffer skey */
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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(3)>,
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L<EVP_PKEY_verify_recover(3)>,
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=head1 HISTORY
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These functions were added in OpenSSL 1.0.0.
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=head1 COPYRIGHT
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Copyright 2006-2018 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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