What is RC6?
--------------
RC6 is a conventional block cipher algorithm, developed by RSA, and in the
final five candidate algorithms of NIST's AES (Advanced Encrytion Standard)
effort.  This implementation uses cipher mode:  Cipher Block Chaining (CBC)
with this algorithm.  It is written in 100% assembly, that`s why it is fast
enough.

Usage:
------
RC6 <e/d> <infile> <outfile> <password>

e/d are means En/DeCrypt.

Notes:
------

RC6 is a block cipher, it processes blocks of 128 bit (16 byte) datas.  The
input data gets padded to 128 bit boundary, so that their length could be
devided by 16 in bytes.  Only after this the RC6 - using 128 bit blocks - can
be applied.  Moreover, this additional encrypted information saves into an
output file, because all 128 bits of data blocks are needed for decrypting.
That`s why the encrypted files are longer by 1-16 bytes than the original.
Another single byte is also added which determines how much padding bytes
were used in the additional information.  This is needed for regaining the
length of the original file while decrypting.  In this way the length of
every enrcypted file is:  X*16+1 byte.

The program reads the whole file into the memory, that's why there must be as
much free RAM as long the file is.

                                            Lay András <lay@netcity.hu>

 PERMSSN    UID  GID    PACKED    SIZE  RATIO     CRC       STAMP          NAME
---------- ----------- ------- ------- ------ ---------- ------------ -------------
[generic]                 2644    2644 100.0% -lh0- c471 Dec 26  1999 rc6
[generic]                  750    1475  50.8% -lh5- 6ccf Dec 26  1999 RC6.readme
---------- ----------- ------- ------- ------ ---------- ------------ -------------
 Total         2 files    3394    4119  82.4%            Jan 27  2000