--------------------------------------------------
From: "Andreas Raab" <andreas.raab at gmx.de>
Sent: Thursday, September 02, 2010 6:10 PM
To: "The general-purpose Squeak developers list" 
<squeak-dev at lists.squeakfoundation.org>
Subject: [squeak-dev] Re: [Cryptography 
Team]Re:DigitalSignatureAlgorithm>>#initRandomNonInteractivelyisnot random

> On 9/2/2010 2:22 PM, Rob Withers wrote:
>>> whereas for example MD2, MD4 (outdated) and DiffieHellman (WAY too
>>> slow) are not.
>>
>> Andreas, I use DiffieHellman for key exchange in my system. It is
>> considered slow? It is a one time use in a connection...
>
> If I remember correctly (it's been a few years since I did this) the 
> problem was the DH had a significant server load for each connection 
> (several seconds for each new connection) whereas RSA had a high inital 
> cost but after that was basically instant. Of course all of this was 
> pre-cog so very different performance tradeoffs but when I did the math, 
> the bottom line was that a DH reconnect of ten people could never be 
> completed in less than 30 seconds simply because each connection would 
> require 3+ seconds server time and (at that point) all of the connections 
> were serialized. It was just a no-go.

Very interesting.   I have never measured it.  I take my prime and generator 
from E.  I just tried a 1024 bit DiffieHellman and it took 65 seconds!  With 
E's numbers I get 315 ms pretty consistently.   This seems to match a 192 
bit DH pretty well.  This is both send and receive messages so is the total 
time for one side.  This is pre-cog.

>
>>> RSA, on the other hand, is somewhere in the middle - it performs
>>> reasonably well (we use it for key exchange in our products) but one
>>> could easily argue that it's not a common enough feature to be
>>> required in Core. Not sure on ElGamal.
>>
>> How do you use RSA for key exchange?
>
> The server generates a new key pair on startup and when the client 
> connects the server sends its public key to the client. The client uses 
> the public key to encrypt the session key for the connection and sends it 
> back. The server decrypts the session key, both ends install a streaming 
> cipher based on the session key and we're done.

Ok, that makes sense.  There is a qualitative security difference between DH 
and this approach.  DH does not pass the key across the wire.  It does 
modulo arithmetic to pass derivative numbers.

To speed things up, we could primitize hot spots:

17.1% {7ms} SHA1>>finalHash
14.6% {6ms} ThirtyTwoBitRegister>>load:
9.8% {4ms} LargePositiveInteger>>+

from SecureRandom

and in raisedTo: modulo:

65.5% {1045ms} Array(SequenceableCollection)>>second
32.5% {519ms} LargePositiveInteger>>>=

Not sure if that would improve with a plugin.

Of course, the same is true of RSA.

Cheers,
Rob

>
> Cheers,
>   - Andreas
>
>>>
>>> But in any case, I think I'll leave this to the experts, which I think
>>> is you, Rob and Ron :-)
>>
>> That's what I got,
>> Rob
>>
>>>
>>> Cheers,
>>> - Andreas
>>>
>>>>
>>>>
>>>> On Sat, Aug 28, 2010 at 6:30 AM, Rob Withers<reefedjib at gmail.com> 
>>>> wrote:
>>>>>
>>>>>
>>>>> --------------------------------------------------
>>>>> From: "Bert Freudenberg"<bert at freudenbergs.de>
>>>>> Sent: Saturday, August 28, 2010 7:13 AM
>>>>> To: "The general-purpose Squeak developers list"
>>>>> <squeak-dev at lists.squeakfoundation.org>
>>>>> Subject: Re: [Cryptography
>>>>> Team]Re:[squeak-dev]DigitalSignatureAlgorithm>>#initRandomNonInteractivelyisnot
>>>>>
>>>>> random
>>>>>
>>>>>>
>>>>>> On 28.08.2010, at 12:59, Rob Withers wrote:
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --------------------------------------------------
>>>>>>> From: "Bert Freudenberg"<bert at freudenbergs.de>
>>>>>>> Sent: Saturday, August 28, 2010 6:42 AM
>>>>>>> To: "The general-purpose Squeak developers list"
>>>>>>> <squeak-dev at lists.squeakfoundation.org>
>>>>>>> Cc: "Squeak Crypto"<cryptography at lists.squeakfoundation.org>
>>>>>>> Subject: Re: [Cryptography Team]
>>>>>>> Re:[squeak-dev]DigitalSignatureAlgorithm>>#initRandomNonInteractivelyis
>>>>>>> not
>>>>>>> random
>>>>>>>
>>>>>>>> It's best to first publish to the inbox. You do not need special
>>>>>>>> permissions for that. Once we're happy with the packages we move
>>>>>>>> them over
>>>>>>>> to trunk.
>>>>>>>
>>>>>>> Done. The following packages are in the Inbox:
>>>>>>>
>>>>>>> CryptoCore
>>>>>>> CryptoCoreTests
>>>>>>> CryptoExtras
>>>>>>> CryptoExtrasTests
>>>>>>> CryptoCerts
>>>>>>> CryptoCertsTests
>>>>>>>
>>>>>>> All tests pass, although I have not tried to load just CryptoCore 
>>>>>>> and
>>>>>>> CryptoCoreTests and run its tests.
>>>>>>>
>>>>>>> Rob
>>>>>>
>>>>>> Ah, should have commented on the package names - didn't think you're
>>>>>> *that* fast ;)
>>>>>
>>>>> I did the work last night.
>>>>>
>>>>>>
>>>>>> The convention is to use hyphenation. As Andreas suggested, that
>>>>>> would be
>>>>>> "Crypto-Core", "Crypto-Core-Tests" etc.
>>>>>
>>>>> The problem with that approach is the the Test package gets included
>>>>> with
>>>>> the core package. In the example of "Kernel" and "KernelTests"
>>>>> hyphenation
>>>>> is not used.
>>>>>
>>>>> Rob
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>
>
>