Source Technologies ST9650

Source Technologies, LLC ST9650 Secure MICR Printer User’s Guide

Decryption Commands

Decryption requires printer processing overhead. In our testing encrypted printer data

steams near or below 100K bytes per page do not seem to affect printer speed in term of

pages per minute or first page out timings. Some testing done with print files from 500K

to 1 Meg per page revealed up to a 30% degradation in speed. It is therefore

recommended the encryption be reserved for the confidential portions of the data when

large file sizes are anticipated.

Set DES Decryption Key Command – &%STSETDESKEY<16 Hex Characters>$

The command requires a MICR Password Command be sent prior to the Key

Command. The Key Command could itself be encrypted and then decrypted in the

printer. The command requires the key data be in a double-byte hex format. The 8 byte

value must be converted to the 16 byte format. The only values that can be contained in

the 16 command bytes are 0 through 9, A through F. Alpha key characters can be upper

or lower case. Command characters must be upper case. Here is an example of a valid

key command - &%STSETDESKEY5f00FF7E3DA938eb$. The key value remains in the

printer until another key command is received. Printer power cycles and printer reset

commands do not affect the key value.

The dollar sign ($) is the command terminator and is required.

Set AES Decryption Key Command – &%STSETAESKEY<32 Hex Characters>$

The command also requires a MICR Password Command be sent prior to the Key

Command.

The key data is similar to DES, but is twice in length with 32 Hex character format

representing the 16 byte or 128-bit key value.

Turn DES Decryption ON – &%STDON$

Turn AES Decryption ON – &%STAON$

All data following the $ command terminator will be decrypted using the current key

value stored in the printer and the DES or AES algorithm. Decryption continues until a

Decryption OFF command is received, a printer panel reset occurs, or printer power is

cycled. Printer software language resets do not stop decryption.

Turn DES Decryption OFF – &%STDOFF$

Turn AES Decryption OFF – &%STAOFF$

The OFF command resides within the encrypted data, and must also be encrypted. The

OFF occurs after an 8-byte block (DES) or 16-byte block (AES) is received and

decrypted. The last block containing the OFF should either have the command right

justified or padded out to the block boundary. Any padding bytes after the $ command

terminator will be discarded.

MICR Features | 6