1997-01-13 - Re: Why are 1024 bit keys the limit right now?

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From: paul@fatmans.demon.co.uk
To: AaronH4321@aol.com
Message Hash: 1fcc6ad634c7dac5a2cbb392fdba52da691c55778b1e51b2b1c479c5405ab0d6
Message ID: <853170077.1023902.0@fatmans.demon.co.uk>
Reply To: N/A
UTC Datetime: 1997-01-13 15:46:10 UTC
Raw Date: Mon, 13 Jan 1997 07:46:10 -0800 (PST)

Raw message

From: paul@fatmans.demon.co.uk
Date: Mon, 13 Jan 1997 07:46:10 -0800 (PST)
To: AaronH4321@aol.com
Subject: Re: Why are 1024 bit keys the limit right now?
Message-ID: <853170077.1023902.0@fatmans.demon.co.uk>
MIME-Version: 1.0
Content-Type: text/plain



> I am just starting at this. I know that part of RSA/PGP's strength comes from
> the size key you choose. What prevents someone from writting a 2048 bit key?
> Is it because computers can't handle it? Is 1024 top of  the prime number
> size right now? Am I way off track? 

2048 bit keys are quite commonly used but the reason that arbitrarily 
large keys are not good is because of the amount of time taken to 
generate the keys then encrypt and decrypt messages with them, PGP 
uses a hybrid system whereby the rsa algorithm encrypts a one time 
session IDEA key, a longer RSA key would result in unacceptably long 
waits for most users when encrypting and decrypting messages.

In the end it comes down to a trade off between speed and security 
and 1024 bits is a sensible compromise for most uses.

 

  Datacomms Technologies web authoring and data security
       Paul Bradley, Paul@fatmans.demon.co.uk
  Paul@crypto.uk.eu.org, Paul@cryptography.uk.eu.org    
       Http://www.cryptography.home.ml.org/
      Email for PGP public key, ID: 5BBFAEB1
     "Don`t forget to mount a scratch monkey"





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