.. efun:: string hmac(int method, string key, string value)
  string hmac(int method, string key, int *  arg )
  :include: <tls.h>

  Calculate the Hashed Message Authenication Code for :arg:`value` based on the digest :arg:`method` and the password :arg:`key`. Return the HMAC.

  :arg:`method` is one of the TLS_HASH_ constants defined in tls.h; not all recognized methods may be supported for a given driven:

    TLS_HASH_SHA1      (1)
    TLS_HASH_SHA224    (2)
    TLS_HASH_SHA256    (3)
    TLS_HASH_SHA384    (4)
    TLS_HASH_SHA512    (5)
    TLS_HASH_MD5       (6)
    TLS_HASH_RIPEMD160 (7)

  If the driver is compiled without OpenSSL or GCrypt support an error is thrown.

  .. usage::

    The example below shows how to compute the SHA1 hmac of a string and an array of characters::

      string s;

      s = hmac(TLS_HASH_SHA1, "secret", "Hello");
      s = hmac(TLS_HASH_SHA1, "secret", ({ 'H', 'e', 'l', 'l', 'o' }) );

  :history 3.3.714 introduced:

  .. seealso:: :efun:`crypt`, :efun:`md5`, :efun:`md5_crypt`, :efun:`sha1`, :efun:`hmac`