Encoding chunks

[tony medeiros]

Hi, I am interested in using gnupg to encode an incoming stream and
output the cipher text while still streaming the plain text.
For example:t P = p1 + p2, + p3; C = gpg_encrypt(P)
How can I use gnupg such that

C = gpg_encrypt(p1) + gpg_encrypt(p2) + gpg_encrypt(p3)

My goal is to intercept a network stream, encode it in gpg, then
continue sending it on its path. I only have access to one chunk at a
time.

Where I am confused is when using gpg.encrypt_file(stream). What is
this returning? Is expecting to encrypt a whole file or just up to the
end of the stream, so the next time I call encrypt_file(stream) it
will continue where it left off.

Do you guys have any suggestions in doing with only keeping
size(chunk) in memory at one time?

Thanks
Tony

[Vinay Sajip]

> Where I am confused is when using gpg.encrypt_file(stream). What is
> this returning? Is expecting to encrypt a whole file or just up to the
> end of the stream, so the next time I call encrypt_file(stream) it
> will continue where it left off.

If you pass encrypt_file a file-like object, then it should work as
you expect, but with a single encrypt_file call rather than multiple
calls. The encrypted stream should be streamed out to gpg's stdout,
which is picked up by the Python code and buffered in memory: if you
want to do this differently (e.g. only keep some parts of the
encrypted file in memory at a time) you will need to handle this
yourself by subclassing GPG. Take a look at the source code to see how
stdout data from gpg is being handled.

Regards,

Vinay Sajip