Re: [pac] Re: Using keys not generated by your module ...

> Actually, Crypt::CBC uses a static IV of "RandomIV" - a holdover from
> Eric Young's stuff. (to verify this, encrypt the same plaintext numerous
> times . . you'll find that the ciphertext never changes. [use
> encrypt_hex() just to make comparisons easy])

Hmm, I can't seem to duplicate this. From my reading of the Crypt::CBC code,
I thought that the "RandomIV" preceded the actual random IV, which is then
read from the ciphertext. For example, I tried this:

    use Crypt::CBC;
    my $cbc = Crypt::CBC->new('my key', 'Crypt::DES');
    print $cbc->encrypt_hex("foo bar baz"), "\n" for 1..3;

And when I run it a couple of times:

    52616e646f6d495689b6ddbbc84461429daf676628d05ce4edfa1c2e9391482c
    52616e646f6d495631992c4bbf3ab656ac151d6204ddd53b0e6c2bf26f2175c6
    52616e646f6d49569b8a3b86e5853c159fd366161cc9f6ec6b30471a1803b20d

                    ^
                    |
---------------------

All ciphertexts start with the same string ("RandomIV"), but then after
those first 8 octets (where the arrow points) they're different.

Am I looking in the wrong place?

> I currently have two alternatives available to Crypt::CBC (the static IV
> bothers me terribly).  The first is Crypt::CBC_R (random IV), which can
> read older Crypt::CBC messages, but not write them; the other is
> Crypt::CBC_IL, a 4-way interleaved cipher block chaining mode.  And yes,
> I've been trying to work with LDS to change the current Crypt::CBC to
> have a 'compat' mode which would be 'SSLeay-compatible'.

This sounds great. It would also be very useful to have an SSH1-compatible
scheme; SSH1 uses a starting IV of all zeroes and basically just the "core"
CBC code. I could point out the main differences that I see between the
current Crypt::CBC and SSH1 compatibile CBC, if you'd be interested.

How are you proposing to work in the 'compat' mode? Using inheritance, or
using a has-a relationship, or through some other method?

Thanks,
Ben