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e1b78bc64d
This will also make it much simpler to generate softlinks name like each function to man-pages containing the info.
77 lines
2.2 KiB
Plaintext
77 lines
2.2 KiB
Plaintext
=pod
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=head1 NAME
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HMAC, HMAC_Init, HMAC_Update, HMAC_Final, HMAC_cleanup - HMAC message
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authentication code
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=head1 SYNOPSIS
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#include <openssl/hmac.h>
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unsigned char *HMAC(const EVP_MD *evp_md, const void *key,
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int key_len, const unsigned char *d, int n,
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unsigned char *md, unsigned int *md_len);
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void HMAC_Init(HMAC_CTX *ctx, const void *key, int key_len,
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const EVP_MD *md);
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void HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, int len);
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void HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len);
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void HMAC_cleanup(HMAC_CTX *ctx);
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=head1 DESCRIPTION
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HMAC is a MAC (message authentication code), i.e. a keyed hash
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function used for message authentication, which is based on a hash
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function.
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HMAC() computes the message authentication code of the B<n> bytes at
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B<d> using the hash function B<evp_md> and the key B<key> which is
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B<key_len> bytes long.
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It places the result in B<md> (which must have space for the output of
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the hash function, which is no more than B<EVP_MAX_MD_SIZE> bytes).
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If B<md> is NULL, the digest is placed in a static array. The size of
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the output is placed in B<md_len>, unless it is B<NULL>.
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B<evp_md> can be EVP_sha1(), EVP_ripemd160() etc.
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B<key> and B<evp_md> may be B<NULL> if a key and hash function have
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been set in a previous call to HMAC_Init() for that B<HMAC_CTX>.
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HMAC_cleanup() erases the key and other data from the B<HMAC_CTX>.
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The following functions may be used if the message is not completely
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stored in memory:
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HMAC_Init() initializes a B<HMAC_CTX> structure to use the hash
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function B<evp_md> and the key B<key> which is B<key_len> bytes long.
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HMAC_Update() can be called repeatedly with chunks of the message to
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be authenticated (B<len> bytes at B<data>).
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HMAC_Final() places the message authentication code in B<md>, which
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must have space for the hash function output.
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=head1 RETURN VALUES
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HMAC() returns a pointer to the message authentication code.
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HMAC_Init(), HMAC_Update(), HMAC_Final() and HMAC_cleanup() do not
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return values.
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=head1 CONFORMING TO
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RFC 2104
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=head1 SEE ALSO
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L<sha(3)|sha(3)>, L<evp(3)|evp(3)>
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=head1 HISTORY
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HMAC(), HMAC_Init(), HMAC_Update(), HMAC_Final() and HMAC_cleanup()
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are available since SSLeay 0.9.0.
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=cut
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