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Re^2: Crypt::CBC and varying the key

by Anonymous Monk
on Mar 16, 2006 at 06:57 UTC ( [id://537062]=note: print w/replies, xml ) Need Help??


in reply to Re: Crypt::CBC and varying the key
in thread Crypt::CBC and varying the key

Yes, I know what CBC is. I *use* CBC. But I want to crypt 2 blocks (not in the sense of the cipher but say strings) of data. The second block has another key from the first one. But the IV is carried over. This is to get two levels of access to the data.

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Re^3: Crypt::CBC and varying the key
by jimbojones (Friar) on Mar 17, 2006 at 20:14 UTC
    Hi

    It looks like you'll have to modify CBC.pm. In my version (2.14), the 'finish' method deletes the current IV. 
        delete $self->{'civ'};
    delete $self->{'buffer'};
    return $result;
}

    [download]
    You'll have to prevent that from happening, and then add a method to return the current (last) IV, instead of the initial IV 
    sub get_civ
{
 return $self->{civ};
}

    [download]
    I have no idea if or how this affects the security of the two messages.

    Hope this helps, J

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