Erwann ABALEA schrieb:
>
> On Wed, 9 Jun 1999, Holger Reif wrote:
>
> > ÃÖ¿ë»ï schrieb:
> > >
> > > Basic assumption here is,
> > > 1. RSA Key size : 256
> >
> > Just remember, this counts for 32 byte...
> >
> > > 2. size of message to be encrypted : 33
> >
> > ...which would make it impossible to encrypt more then 32 byte
> > within one rsa operation.
>
> Not exactly..... You can encrypt any block size with any key size.... even
> a 12KB block with a 16bit key....
not with openssl ;-) Because RSA_NONE checks wether the lengths equals
> Mathematically, there's no
> limitation....
>
> But if you use a block bigger than the key size, you won't be able to
> decrypt and retrieve the original message....
Well, you can retrieve a lot of possible messages, but you
can't determine which is correct if you don't choose to restrict
to something smaller then the modulus.
> In fact, the data you want to encrypt, when expressed as a bigint, MUST be
> at most equal to the modulus-1 if you want to decrypt the data...
And here might be some problem within the implementation
for RSA_NONE. It only checks wether the number of bytes
are equal and assumes the bitstring buffer is smaller
then the modulus. Should we check more carefully here?
--
Holger Reif Tel.: +49 361 74707-0
SmartRing GmbH Fax.: +49 361 7470720
Europaplatz 5 [EMAIL PROTECTED]
D-99091 Erfurt WWW.SmartRing.de
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