Re: Does the IV for CBC really have to be zeros?

[Richard Levitte - VMS Whacker]

noel> Is this an error in documentation?  According to Applied Crypto,
noel> Schneier, p 194, the IV in CBC mode ciphers should be different for
noel> each message.  Looking at the source for BF_cbc_encrypt(), it looks
noel> like iv can be initialized with any 64 bytes.

You're right, that is a documentation glitch.  I got confused by SSH
wehn I rwote that.  SSH explicitely requires that the ivec be
initialised to 0.  What's important is that the recipient gets to know
what initial ivec was used (as is mentioned in the same page).

noel> Also, it looks like this code will fail unless the processor's word
noel> size is 32 bits.  Does openssl work on an Alpha?

OpenSSL works on the Alphas where it has been tested, as far as I
know.  From what I can see, the BF code will use 8 bytes, using n2l
and other macros.

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