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A project log for Ink Tank Encryption

I'm trying to find out how to use the EEPROM chips that might be in CLI-226 ink tanks to share public keys for public-private key encryption

alphaninjaalpha_ninja 09/04/2015 at 23:472 Comments

Hi there! Long time no see!

Here's what I just found out.

All cartridges share one bus.

This makes sense.

So, I tested inserting one cartridge after the other.

Magenta is doing the sensing, I'm inserting black, then cyan, then pigment black, then yellow.

Magenta only

0xdef800 0x000000 0xdefc00 0x000000 0xdee400 0x000000 0xdef200 0x000000 0xdeec00 0x000000

Magenta & Black

0xdef800 0x000000 0xdefc00 0x000000 0xdee400 0x000000 0xdef200 0x000000 0xdeec00 0xdc0000

0xdf2c64

Magenta & Black & Cyan

0xdef800 0x000000 0xdefc00 0x000000 0xdee400 0xbc0000 0xdef200 0x000000 0xdeec00 0xdc0000

0xdf2432 0xdf2c64

Magenta & Black & Cyan & Pigment Black

0xdef800 0x000000 0xdefc00 0xef0000 0xdee400 0xbc0000 0xdef200 0x000000 0xdeec00 0xdc0000

0xdf3c32 0xdf2432 0xdf2c64

Magenta & Black & Cyan & Pigment Black & Yellow

0xdef800 0xcf0000 0xdefc00 0xef0000 0xdee400 0xbc0000 0xdef200 0x000000 0xdeec00 0xdc0000

0xdf3832 0xdf3c32 0xdf2432 0xdf2c64

I don't know why I didn't test for this.

Anyway, these are the conclusions I can make from this:

1. The read protocol is as follows:

0xdef800 (Yellow) 0x*****

0xdefc00 (Pigment Black) 0x*****

0xdee400 (Cyan) 0x*****

0xdef200 (Magenta) 0x*****

0xdeec00 (Black) 0x*****

2. The write protocol is as follows:

0xdf2c64 (Black)
0xdf2432 (Cyan)
0xdf3c32 (PgBk)
0xdf3832 (Yellow)
0xdf3232 (Magenta)


Edit:

Turns out the cartridge I used for testing had the traces cut. Oops :P

I've added the values I got from another test, but won't be retesting the values I measured above :)

Discussions

frankstripod wrote 09/05/2015 at 02:59 point

The title of the log implies you were wrong, but actually its a great find.

  Are you sure? yes | no

alpha_ninja wrote 09/05/2015 at 03:32 point

Well, what I'm afraid of is that these things have vastly smaller storage space than I initially assumed. That would suck.

Also, not that related, but https://github.com/NicholasCLewis/InkShield is cool.

  Are you sure? yes | no