[Cryptography] NIST Workshop on Elliptic Curve Cryptography Standards

[Tony Arcieri]

On Tue, May 19, 2015 at 2:48 PM, Adrian McCullagh <amccullagh at live.com>
wrote:

>  Further, I think the reason for the further reduction to 56 bit was for
> the introduction of a parity correction.
>
> I am unaware of the NSA being involved in any of this.
>

The NSA wanted 48-bits. IBM wanted 64-bits. So they split the difference at
56-bits.

"Parity bits" were used to explain the odd choice of 56-bits, but clearly 8
parity bits for 56-bits of data doesn't make a whole lot of sense.

You can read about it in Wikipedia, or for a more in-depth account, Steven
Levy's book "Crypto":

https://en.wikipedia.org/wiki/Data_Encryption_Standard#NSA.27s_involvement_in_the_design

-- 
Tony Arcieri
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