encryption

[Richard Kreiss]

I have an application where I am encrypting credit card numbers.  

I have a file key I am using for all the encryptions.  Prior to the
encryption I am creating a nonce by creating an alphanumeric value from the
original card number.  This value is store in the record.

I ran a process which encrypted about 5,000 card numbers.  I had tested both
the encryption and decryption routines individually on a number of these
records before applying encryption to all of the records.  

When I went to do a mass decryption, I found 4 records which would not
decrypt.  Having a duplicate record in another file, I replaced the
encrypted value with the actual card number and then encrypted the number
again.  When I went to decrypt the value, it failed again.


Type="AES"
Cassie=Primary Key (lookup to a master record
Special=nonce  (VNQ1Z99891) 
Number= card number with spaces removed

En(20,*)=encrypt(number,type,cassie,special)

Un(20,*)=decrypt(number,type,cassie,special)

Anyone have any idea why this would work 4,996 times and not on 4 records?

Until I solve this problem, I can't go live with this.


Richard Kreiss
GCC Consulting
rkreiss at gccconsulting.net