[10385] in cryptography@c2.net mail archive

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Re: Welome to the Internet, here's your private key

daemon@ATHENA.MIT.EDU (Dean Povey)
Tue Feb 5 10:31:30 2002

Message-Id: <200202050334.g153YL220597@thunder.dstc.qut.edu.au>
To: Greg Rose <ggr@qualcomm.com>
Cc: Bill Frantz <frantz@pwpconsult.com>,
	cryptography@wasabisystems.com
In-Reply-To: Message from Greg Rose <ggr@qualcomm.com> 
   of "Tue, 05 Feb 2002 14:17:24 +1100." <4.3.1.2.20020205125907.01e043f8@127.0.0.1> 
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Date: Tue, 05 Feb 2002 13:34:21 +1000
From: Dean Povey <povey@dstc.qut.edu.au>

>At 04:24 PM 2/4/2002 -0800, Bill Frantz wrote:
>>At 2:09 PM -0800 2/4/02, lynn.wheeler@firstdata.com wrote:
>> >1) A typical message would have a 20-byte nonce random number, which
>> >computed to a 20-byte SHA1 and then encrypted with RSA resulting in 20-byte
>> >signature (basic message plus 40-byte infrastructure overhead, signature
>> >plus nonce).
>
>I think an RSA signature can be no smaller than the key modulus, so an RSA 
                                    ^^^^^^^ larger
>sig with a 1024-bit key is going to be 128 bytes plus some overhead, no 
>matter what. I think you (Lynn) meant DSA here. Or maybe you did mean RSA, 
>given that you then go on to DSA... I don't know.

But the analysis still holds of course, the modulus is just an upper 
bound, and  this is just me being pedantic.

-- 
Dean Povey,              |em: dpovey@wedgetail.com|  JCSI: Java security toolkit
Senior S/W Developer     |ph:  +61 7 3864 5120    | uPKI: Embedded/C PKI toolkit
Wedgetail Communications |fax: +61 7 3864 1282    |       uASN.1: ASN.1 Compiler
Brisbane, Australia      |www: www.wedgetail.com  | XML Security: XML Signatures 



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