code: function SHA1_encode(source) { // @arg Uint8Array
                                 // @ret Uint8Array
  //{@dev
      $valid($type(source, "Uint8Array"), SHA1_encode, "source");
  //}@dev
  
      var buffer = _createBufferWith64BytePadding(source);
      var hash   = _SHA1(buffer); // [a, b, c, d, e]
      var result = new Uint8Array(20);
  
      for (var ri = 0, hi = 0; hi < 5; ri += 4, ++hi) {
          result[ri    ] = hash[hi] >>> 24 & 0xff;
          result[ri + 1] = hash[hi] >>> 16 & 0xff;
          result[ri + 2] = hash[hi] >>>  8 & 0xff;
          result[ri + 3] = hash[hi]        & 0xff;
      }
      return result;
  }
docs: SHA1.encode(source:Uint8Array):Uint8Array --- implements ------------------------------------------