Hi Soren,
Sorry, I should have gone into more detail.
What is the best approach to generating unique initialization vectors for
block ciphers such as AES in CFB mode?
I would personally use the Crypto++ RNG. There are better ways to
generate, rather than going for 1 byte at a time.
CryptoPP::AutoSeededRandomPool rng;
std::string Key( "BYTE key[ CryptoPP::AES::DEFAULT_KEYLENGTH ]
=\r\n { " );
std::string IV( ("BYTE iv[ CryptoPP::AES::BLOCKSIZE ] =\r\n { " );
//
// IV
//
for( INT i = 0; i < CryptoPP::AES::BLOCKSIZE; i++ ) {
BYTE b = rng.GenerateByte();
...
}
How does AutoSeededRandomPool work? Is it guaranteed
not to return the same number twice?
Gleaned from osrng.cpp:
if Not WIN32
Nonblocking RNG: /dev/urandom
Blocking RNG: /dev/random
If WIN32
Use Microsoft Cryptographic Provider
IIRC, MCP uses an OS derived value, stored in the registry (this is
for NT systems, not 9x systems)
Jeff
On 9/4/06, Søren Dreijer <[EMAIL PROTECTED]> wrote:
Yes, I know how you use it but I don't see anything about how to use it to
generate a unique IV..
________________________________
> Date: Mon, 4 Sep 2006 17:27:38 -0400
> From: [EMAIL PROTECTED]
> To: [email protected]
> Subject: Re: Generating Unique Initialization Vectors
>
> Hi Soren,
>
> > > How does AutoSeededRandomPool work?
>
http://www.eskimo.com/~weidai/cgi-bin/fom-serve/cache/83.html
>
> Jeff
>
> On 9/4/06, Søren Dreijer <[EMAIL PROTECTED]> wrote:
> >
> > Hey,
> >
> > What is the best approach to generating unique
initialization vectors for
> > block ciphers such as AES in CFB mode?
> >
> > How does AutoSeededRandomPool work? Is it guaranteed
not to return the same
> > number twice?
> >
> > - Soren
> >
> > ________________________________
> > Call friends with PC-to-PC calling -- FREE Try it now!
>
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