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<H1>[pycrypto] Typo or bug?</H1>
<B>Dave Pawson</B>
<A HREF="mailto:pycrypto%40lists.dlitz.net?Subject=Re%3A%20%5Bpycrypto%5D%20Typo%20or%20bug%3F&In-Reply-To=%3CCAEncD4cgP3kSXc-%3D%3Db%3DQeGxKhE%2BbFOyH2j0E-Hj0h8p8QeXUdw%40mail.gmail.com%3E"
TITLE="[pycrypto] Typo or bug?">dave.pawson at gmail.com
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<I>Tue Jun 26 07:59:29 EDT 2012</I>
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<PRE>On 26 June 2012 12:31, Legrandin <<A HREF="http://lists.dlitz.net/cgi-bin/mailman/listinfo/pycrypto">gooksankoo at hoiptorrow.mailexpire.com</A>> wrote:
><i> Choice of the IV is critical for security.
</I>><i> For CFB, the combination IV and key must be use only with one message, and
</I>><i> never occur again.
</I>><i> That is explained here:
</I>><i>
</I>><i> <A HREF="https://www.dlitz.net/software/pycrypto/api/current/Crypto.Cipher.blockalgo-module.html#MODE_CFB">https://www.dlitz.net/software/pycrypto/api/current/Crypto.Cipher.blockalgo-module.html#MODE_CFB</A>
</I>
Thanks.
(I think I need more reading to select one!)
><i>
</I>><i> IV needs indeed to be share by the party encrypting and by the party
</I>><i> decrypting the message.
</I>><i>
</I>><i> Up to pycrypto 2.5, when no iv was provided to new() a string of zeroes was
</I>><i> automatically used.
</I>><i> Depending on your application, that may or may not be a problem. It is wiser
</I>><i> to always make iv explicit.
</I>
Which explains why my 'old' code failed. Thanks.
Needing both key and iv... It sounds like asking for two keys to unlock a box?
Is that the idea?
regards
--
Dave Pawson
XSLT XSL-FO FAQ.
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<A HREF="http://www.dpawson.co.uk">http://www.dpawson.co.uk</A>
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