docs: function decode_base64(salt) {
          var decoded = new Array(16);
          var i = 0, j = 0, c1, c2;
          while(true) {
              c1 = index_64[salt.charCodeAt(i++)-46];
              c2 = index_64[salt.charCodeAt(i++)-46];
              decoded[j++] = (c1 << 2 | c2 >> 4) & 0xff;
              if (i === 22) break;
              
              c1 = c2 << 4;
              c2 = index_64[salt.charCodeAt(i++)-46];
              decoded[j++] = (c1 | c2 >> 2) & 0xff;
  
              c1 = c2 << 6;
              c2 = index_64[salt.charCodeAt(i++)-46];
              decoded[j++] = (c1 | c2) & 0xff;
          }
          return decoded;
      }