on 5 of
   [HMAC] also discusses truncating the output of HMAC; the rule is that
   we should keep the more significant bits (the bits in the left,
   assuming a network byte order (big-endian)).
<p>
   In sections 2 and 3 we provide test cases for HMAC-MD5 and HMAC-SHA-
   1, respectively. Each case includes the key, the data, and the
   result.  The values of keys and data are either hexadecimal numbers
   (prefixed by &quot;0x&quot;) or ASCII character strings in double quotes. If a
   value is an ASCII 