Crypto.PublicKey.RSA.error: Plaintext too large

hi!

I am getting an error - Crypto.PublicKey.RSA.error: Plaintext too
large - when verifying the signature of a document.
What i am doing is - the document and the signature are downloaded off
the net, my verify script then connects to a server and obtains a
public key. It then uses the public key to verify the signature.
The whole thing works fine when i do the same thing in the interactive
interpreter. Its only when i download the files and obtain the public
key from the server and then verify, that i get the above error.

any suggesstions...ideas???

cheers

ajay