encryption bloats file

David Shaw dshaw at jabberwocky.com
Sat Jan 10 04:49:54 CET 2009


On Fri, Jan 09, 2009 at 10:33:52PM -0500, Scott Lambdin wrote:
> I found a file in rejects, but it may be partial.  It gives us some
> information, though.
> 
> The pgp file was 406184088 bytes and unencrypted is 175246253 bytes.
> 
> gpg -v -v -o a_file.out -d a_file.pgp
> 
> gpg: armor: BEGIN PGP MESSAGE
> gpg: armor header: Version: McAfee E-Business Server v7.5 - Full License
> :pubkey enc packet: version 3, algo 1, keyid 123456789012345
>         data: [2047 bits]
> gpg: public key is ABCD1234
> You need a passphrase to unlock the secret key for
> user: "Janeane Garofalo <JG at thyservice.com>"
> 2048-bit RSA key, ID ABCD4321
> 
> gpg: public key encrypted data: good DEK
> :encrypted data packet:
>         length: 42097820
> gpg: encrypted with 2048-bit RSA key, ID ABCD4321
> gpg: IDEA encrypted data
> :compressed packet: algo=1
> :literal data packet:
>         mode t (74), created 1509949440, name="file-100-1",
>         raw data: 227869810 bytes
> gpg: original file name="file100"
> gpg: no valid OpenPGP data found.
> gpg: fatal: zlib inflate problem: invalid block type
> secmem usage: 2208/4704 bytes in 5/15 blocks of pool 4960/32768

That's helpful, as it indicates that the file was corrupt.  This could
explain why an encrypted file is so much larger than the decrypted
file - the decrypted file is truncated because the decryption failed
partway through.  Of course, that could just be this rejected file.

Can you check if your real file has some non-OpenPGP cruft glued to
the end of it?

David



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