hmac(3) - NetBSD Manual Pages

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HMAC(3)                 NetBSD Library Functions Manual                HMAC(3)


NAME

     hmac -- compute a key-Hash Message Authentication Code


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <stdlib.h>

     ssize_t
     hmac(const char *hname, const void *key, size_t klen, const void *text,
         size_t tlen, void *digest, size_t dlen);


DESCRIPTION

     The hmac() function computes the key-Hash Message Authentication Code per
     RFC 2104 and places the result in digest writing up to dlen bytes.  The
     actual number of bytes that would be written is returned.

     The hash functions supported are: md2, md4, md5, rmd160, sha1, sha224,
     sha256, sha384, and sha512.


RETURN VALUES

     The hmac() function returns -1 if the hname is not found.  Otherwise the
     actual length of the digest string is returned (which could be bigger or
     smaller than dlen).  This length depends on the hashing function
     selected.


SEE ALSO

     md2(3), md4(3), md5(3), openssl_HMAC(3), openssl_MD2(3), openssl_MD4(3),
     openssl_MD5(3), rmd160(3), sha1(3), sha2(3)


STANDARDS

     RFC 2104.


NOTES

     The maximum digest length has been extended from 64 to 128 bytes to han-
     dle SHA2.


HISTORY

     The hmac() function appeared in NetBSD 8.

NetBSD 10.99                     May 22, 2018                     NetBSD 10.99