 SHA-1 using an existing SHA-1 library.  It assumes that the SHA-1
   library has similar API's as those of the MD5 code described in RFC
   1321.  The code for HMAC-MD5 is similar, just replace the strings
   &quot;SHA&quot; and &quot;sha&quot; with &quot;MD5&quot; and &quot;md5&quot;. HMAC-MD5 code is also listed in
   <a href="rfc2104.html">RFC 2104</a>.
<p>
   #ifndef SHA_DIGESTSIZE
<br>
   #define SHA_DIGESTSIZE  20
<br>
   #endif
<p>
   #ifndef SHA_BLOCKSIZE
<pre>
   #define SHA_BLOCKSIZE   64
   #end