Conversation
q@glauca.space

Q ✨ @ CoSin (DECT: 7960)

I believe, I have reversed engineered the signature on IATA boarding passes with TSA-PreCheck

I think it is ECDSA NIST-256 SHA-256. If anyone has any more TSA-PreCheck boarding passes they’re willing to share, would be useful to check I’ve got it right.

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supersat@defcon.social

Karl

Reply to @q@glauca.space

@q I think there are a couple of different algorithms, identified by the first digit in the signature field.

IIRC, PreCheck is designated by a "3" in the selectee field of a IATA BCBP-compatible boarding pass.

Previously, unsigned barcodes could get you through, but only with the PDF417 symbology.

That changed after this DEF CON presentation: https://youtu.be/qnq0UfOUTlM?t=2162

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supersat@defcon.social

Karl

Reply to @supersat@defcon.social

@q I did manage to pull off the firmware of one I got at a government surplus auction. It uses crypto++. Seems like a quality crypto library.

Unclear how well airlines have protected their signing keys. If they use a poor RNG, some DSA schemes let you recover the private key.

It is up to the airlines to sign their own boarding passes. Public keys are loaded through the USB ports on the boarding pass scanners.

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osandov

Omar Sandoval

Reply to @supersat@defcon.social
@supersat @q I remember when you were asking for old boarding passes (to try to figure out how they were generating nonces, maybe?)
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supersat@defcon.social

Karl

Reply to @osandov

@osandov @q yeeeeep! Was looking for repeated values of r: https://rdist.root.org/2010/11/19/dsa-requirements-for-random-k-value/

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