The document describes three encryption challenges from 1997 to 1999 with increasing difficulty. The secret messages revealed after each challenge were "Many hands make light work", "Time for those 128-256 bit keys", and "See you in Rome!". It also provides a high-level overview of the AES encryption process which includes byte substitution, shift rows, mix columns, and add round key steps to encrypt private data like credit card numbers using a secret key.

4. Challenge 1
• 1997
• 84 days
• “ The secret
message is:
Many hands
make light work”
Challenge 2
• 1998
• 3 Days
• “Time for
those 128-
256 bit
keys”
Challenge 3
• 1999
• 22 hrs 15 mins
• “See you in
Rome !”

6. Private Data
Ex: Credit card no.
Secret Key

7. Ciphered Text
Secret Key

8. Byte Substitution
Shift Rows
Mix Columns
Add Round Keys
Encryption

9. Byte
Substitution
• Data is
converted
into a matrix
Shift Rows
• Rows are
shifted to
left
Mix Column
Add Round
Key
Columns are
transformed
By a special
function
Bytes of matrix
are x-or’ed to key