security: PGPainless ignoring bad checksum?

[tomholub]

The behavior on the Android app is faulty when using the Kotlin implementation (on right side). It's supposed to fail, like it did with NodeJS (on the left).

@IvanPizhenko could you see if this is because we have some custom code for parsing armored messages (in which case we should use the correct PGPainless code) or because this is a bug in PGPainless?

[tomholub]

@DenBond7 the bad checksum needs to be fixed in PGPainless

However, the MDC looks like this would be for you to fix - most likely PGPainless already returns that error, but the error is not getting rendered I think?

[tomholub]

I'll move this into a separate issue.

[DenBond7]

but the error is not getting rendered I think?

It can be true. I haven't investigated that yet.

[IvanPizhenko]

This is BouncyCastle bug. Despite BC ArmoredInputStream promises that it will throw on bad checksum, it doesn't in this case. But checksum is really wrong:

$ gpg --dearmor decrypt\ -\ issue\ 1347\ -\ wrong\ checksum.txt 
gpg: CRC error; 15D74A - 15D082

[IvanPizhenko]

@tomholub I am going to report this, but BouncyCastle release cycle is quite long (may be half of year or even year), so their fix is very unlikely to be available quickly. So I suggest to take BC's ArmoredInputStream code, put it into separate class and try to fix and use that fixed class until BC developers fix their original one and publish new BC version with that fix. If we fix that, we may even submit a patch to them.

[IvanPizhenko]

@tomholub Or maybe we should put that fixed stream into PGPainless.