[Cryptography] NIST Workshop on Elliptic Curve Cryptography Standards

[Bill Frantz]

On 5/19/15 at 2:48 PM, amccullagh at live.com (Adrian McCullagh) wrote:

>I am unaware of the NSA being involved in any of this.  My 
>understanding was that the NSA was involved in adjusting the 
>S-Box structure.  Further the NSA refused to say why they made 
>the adjustments;  that is they never justified why they did 
>what they did.

My understanding is they changed it to protect against 
differential cryptanalysis. At the time, differential 
cryptanalysis was known by NSA, but not generally known in the 
public crypto community. (The public crypto community was almost 
non-existant at the time.) NSA protected a classified attack 
while making DES's security basically as good as a brute force 
attack. All users of DES had a clear ideas of how much 
protection it offered with its 56 bit key. Some have said that 
this is the last thing NSA did to improve civilian security.

Cheers - Bill

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