gpg writes junk forever when decrypting

[Gou Yang]

Hello Henry,

Thank You for doing the test. Can you send me a public key? If you sent me a 
public key, I could have the specific person encrypt sample data. I can then 
purposely damage the file to see if you could reproduce the problem.

Thanks,
Gou

>From: Henry Hertz Hobbit <hhhobbit at securemecca.net>
>To: gnupg-users at gnupg.org
>Subject: Re: gpg writes junk forever when decrypting
>Date: Tue, 12 Dec 2006 11:57:10 -0700
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>"Gou Yang" <mega408 at hotmail.com> wrote:
>
> > Hello,
> >
> > I think I've hit a bug in gpg. When I try and decrypt a corrupt
> > pgp file, it  looks like it is working but when it hits the
> > corrupt part of the file, I see this error pop up:
> >
> > gpg: no valid OpenPGP data found.
> > gpg: block_filter 0x80e8ac0: read error (size=11072,a->size=27456)
> > gpg: block_filter 0x80e8a98: read error (size=14947,a->size=39523)
> >
> > When this error pops up, gpg goes out of control and starts
> > appending junk to the decrypted file and never stops appending
> > junk.
> >
> > I've let it sit up to 50GB before I killed gpg. The original file
> > is only about 1GB but I wanted to see if it would ever stop. I've
> > looked around but  I didn't see anyone else who had this problem
> > and resolved it.
> >
> > I could verify the signature prior to attempting to decrypt the
> > file but the file isn't signed.
> >
> > Any suggestions? Any workaround? Anyone else have this problem?
>
>I have tried this with the following combinations (my default
>symmetric cipher is TWOFISH).
>
>1. Encrypted symmetrically with TWOFISH, AES192, AES256, DES,
>    and BLOWFISH ciphers.
>
>    gpg -a -c --force-mdc --cipher-algo ${CIPHER} \
>       < ReadMe.txt > ReadMe.txt.asc
>
>    Twiddled two characters in ReadMe.txt.asc.  Tried to decrypt with:
>
>    gpg -d < ReadMe.txt.asc > ReadMe.txt
>
>    Result: decryption stopped, output file size ZERO.
>
>2. Encrypted and signed asymmetrically to myself with TWOFISH,
>    AES, and AES256 used for the symmetric ciphers.
>
>    gpg -a -r hhhobbit at securemecca.net -e -s \
>       < ReadMe.txt > ReadMe.txt.asc
>
>    Twiddled two characters in ReadMe.txt.asc.  Tried to decrypt with:
>
>    gpg -d < ReadMe.txt.asc > ReadMe.txt
>
>    Result: decryption stopped, output file size ZERO.
>
>3. On a file that is just a text file I get the following message:
>
>gpg: no valid OpenPGP data found.
>gpg: decrypt_message failed: eof
>
>I have tried the use of several more symmetric ciphers and the
>result is always the same.  The instant I twiddle just two
>characters in the encrypted [ / signed ] file I can't decrypt
>and the output file size is ZERO.  The failure given for the
>asymmetric encryption is this for one of them:
>
>gpg: CRC error; 2DC30B - 9AAB55
>gpg: encrypted_mdc packet with unknown version 255
>
>And the one I get for symmetric encrypion is this for one
>of them:
>
>gpg: CRC error; 404350 - 94DB54
>gpg: encrypted_mdc packet with unknown version 255
>
>In all cases if it failed, I end up with the output file
>being of size ZERO.  I am using 1.4.6 with keys that were
>created with 1.4.2 (at least I believe that was what it was).
>
>I suspect you have either a damaged file system or damaged
>keys.  But without more particulars I don't know what you are
>looking at, because in all cases, I end up with a file size of
>ZERO.  That also happens when I delete quite a few characters.
>
>HHH

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