Terms & Definitions
xor-rotate and fold
xor-rotate and fold operation
uses an internal buffer of 20 octets, initialized with zeros.
It processes input, 20 octets at a time.
If the input length is not a multiple of 20 octets,
then that input data is padded with zeros until it is a
multiple of 20 octets.
Every time the operation receives another 20 octets of input,
the internal buffer is circular left rotated by 1 bit, and
the 20 octets of input is then xor-ed into the internal buffer.
When the input has been exhausted, the internal buffer is
returned as output.