mirror of https://github.com/openssl/openssl.git
74 lines
2.5 KiB
Plaintext
74 lines
2.5 KiB
Plaintext
=pod
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=head1 NAME
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PKCS5_PBKDF2_HMAC, PKCS5_PBKDF2_HMAC_SHA1 - password based derivation routines with salt and iteration count
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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int PKCS5_PBKDF2_HMAC(const char *pass, int passlen,
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const unsigned char *salt, int saltlen, int iter,
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const EVP_MD *digest,
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int keylen, unsigned char *out);
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int PKCS5_PBKDF2_HMAC_SHA1(const char *pass, int passlen,
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const unsigned char *salt, int saltlen, int iter,
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int keylen, unsigned char *out);
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=head1 DESCRIPTION
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PKCS5_PBKDF2_HMAC() derives a key from a password using a salt and iteration count
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as specified in RFC 2898.
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B<pass> is the password used in the derivation of length B<passlen>. B<pass>
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is an optional parameter and can be NULL. If B<passlen> is -1, then the
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function will calculate the length of B<pass> using strlen().
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B<salt> is the salt used in the derivation of length B<saltlen>. If the
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B<salt> is NULL, then B<saltlen> must be 0. The function will not
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attempt to calculate the length of the B<salt> because it is not assumed to
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be NULL terminated.
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B<iter> is the iteration count and its value should be greater than or
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equal to 1. RFC 2898 suggests an iteration count of at least 1000. Any
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B<iter> less than 1 is treated as a single iteration.
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B<digest> is the message digest function used in the derivation. Values include
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any of the EVP_* message digests. PKCS5_PBKDF2_HMAC_SHA1() calls
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PKCS5_PBKDF2_HMAC() with EVP_sha1().
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The derived key will be written to B<out>. The size of the B<out> buffer
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is specified via B<keylen>.
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=head1 NOTES
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A typical application of this function is to derive keying material for an
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encryption algorithm from a password in the B<pass>, a salt in B<salt>,
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and an iteration count.
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Increasing the B<iter> parameter slows down the algorithm which makes it
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harder for an attacker to perform a brute force attack using a large number
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of candidate passwords.
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=head1 RETURN VALUES
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PKCS5_PBKDF2_HMAC() and PBKCS5_PBKDF2_HMAC_SHA1() return 1 on success or 0 on error.
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=head1 SEE ALSO
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L<evp(7)>, L<RAND_bytes(3)>,
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L<EVP_BytesToKey(3)>
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=head1 COPYRIGHT
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Copyright 2014-2016 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (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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