Re: "block incorrect" when recovering session info

I found the mistake.

I was hitting the same issue as described here:
http://bouncy-castle.1462172.n4.nabble.com/Decryption-issues-InvalidCipherTextException-unknown-block-type-td4656868.html

That is, while iterating through the PGPPublicKeyEncryptedData iterator,
I wanted to get a list of *all* recipient key Ids.

Unfortunately during that process I overwrote the
PGPPublicKeyEncryptedData object which belonged to my key. So any time
the last EncryptedData block would belong to my key, the decryption
would work just fine. Otherwise I would try to decrypt another keys
PGPPublicKeyEncryptedData block using my key, which would obviously fail.

The solution was quite simple in my case. I just used another variable
to store the PGPPublicKeyEncryptedData object belonging to my key.


Am 25.06.2018 um 16:46 schrieb Paul Schaub:
> Hi!
>
> I'm currently having a strange problem with my project.
>
> When I try to decrypt a message using BC 1.59 for Java, I often get the
> following stacktrace when trying to decrypt a message that has been
> encrypted using RSA-4096 bit OpenPGP keys.
>
> org.bouncycastle.openpgp.PGPException: exception encrypting session
> info: block incorrect
> Caused by: org.bouncycastle.openpgp.PGPException: exception encrypting
> session info: block incorrect
>     at
> org.bouncycastle.openpgp.operator.bc.BcPublicKeyDataDecryptorFactory.recoverSessionData(Unknown
> Source)
>     at
> org.bouncycastle.openpgp.PGPPublicKeyEncryptedData.getSymmetricAlgorithm(Unknown
> Source)
> Caused by: org.bouncycastle.crypto.InvalidCipherTextException: block
> incorrect
>     at
> org.bouncycastle.crypto.encodings.PKCS1Encoding.decodeBlock(Unknown Source)
>     at
> org.bouncycastle.crypto.encodings.PKCS1Encoding.processBlock(Unknown Source)
>     at
> org.bouncycastle.crypto.BufferedAsymmetricBlockCipher.doFinal(Unknown
> Source)
>     ... 15 more
>
> The error happens when I try to print out, which symmetric algorithm has
> been used
> (PGPPublicKeyEncryptedData#getSymmetricAlgorithm(PublicKeyDataDecryptorFactory).
>
> I suspect this happens when an invalid key is being read, but the fact,
> that debugging is disabled (I conclude this from the "Unknown Source" in
> the stacktrace) makes it hard to get to the cause of the problem.
>
> My questions are:
>
> Am I right in my assumption, that the error is caused by a faulty key?
> If so, do you have a hint for me, how I can prevent this from happening?
>
> Do you have an idea, how I could fix the "Unknown Source" in the
> stacktrace? And if this is caused by BC releases being compiled with
> debugging disabled:
>
> Is is possible to have BC compiled with "-g:source,lines" to allow
> easier debugging? Or is this a security feature?
>
> Greetings Paul
>
>
>