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

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.

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

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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	[reply] [d/l] [select]

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

CBC.pm

    delete $self->{'civ'};
    delete $self->{'buffer'};
    return $result;
}
[download]

sub get_civ
{
 return $self->{civ};
}
[download]

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