Newbie Q: decryption

[Joseph Oreste Bruni]

Two things:

1) You can't decrypt a file with a public key. Obviously the company  
who sent you the file doesn't understand public-key encryption either  
because they would need YOUR public key in order to encrypt files to  
you. The first step for them would have been to request a key from  
you. On the other hand, they might have merely signed the file and  
the public key would be used by you to "verify" the signature and it  
might not be encrypted at all. See next.

2) The "mpi too large" message would indicate to me that the file is  
most like corrupted by the file transfer process. Check to make sure  
that if the file is binary that the transfer method does not perform  
conversion on end-of-line characters.


Another thing you can try to examine the file is to use the "--list- 
packets" command.

$ gpg --list-packets <filename>

This will tell you (usually) whether the file is valid OpenPGP data,  
as well as the algorithm and key ID used to encrypt the file (if it  
is encrypted and not just corrupted).

Regards,
Joe

On Feb 26, 2007, at 5:36 PM, Jon Drukman wrote:

> A company I'm getting a data feed from sent me a public key and an
> encrypted file.  I want to decrypt it, but I don't know I'm doing.  My
> naive approach is not working:
>
> $ gpg --homedir=/var/httpd/keyring --decrypt upc.xml.pgp
> gpg: WARNING: using insecure memory!
> gpg: please see http://www.gnupg.org/faq.html for more information
> gpg: mpi too large for this implementation (40856 bits)
>
> the public key is in the file "nf_key".  i thought i imported it but i
> don't how to tell if i did it right, or if it's even the right key for
> the file.
>
> help!
> -jsd-
>
>
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