I've attached the source (a small C file) I use which has some explanation
of what's happening. Perhaps I am setting the exponent incorrectly??
thanks
bruce
----- Original Message -----
From: "Reddie, Steven" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, March 13, 2001 12:08 PM
Subject: RE: How do I construct an instance of RSA using n & e
> I don't know about reversing the modulus. Are you using PKCS#11 functions
> to retrieve the key components? If so, you shouldn't need to reverse the
> bytes as the values already come back in the right endianness. Perhaps
> there is something else that is wrong? Also, if you really do need to
> reverse the bytes of the modulus then you will also need to reverse the
> bytes of the exponent.
>
> If it is the PKCS#11 interface that you're using then the sign operation
> will be being performed with PKCS#1 padding, and so you will need to use
the
> same padding mode during verification.
> Steven
> --
> Steven Reddie <[EMAIL PROTECTED]>
> Senior Software Engineer
> Computer Associates Pty Ltd (Australia)
>
>
> > -----Original Message-----
> > From: bruce cartland [SMTP:[EMAIL PROTECTED]]
> > Sent: Friday, March 09, 2001 6:19 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: How do I construct an instance of RSA using n & e
> >
> > thank you (and SHenson)
> >
> > it works. To test I use the command line tools to generate a key pair,
> > dump
> > the modulus and then initialise an RSA struct directly using the modulus
> > and
> > exponent. This correctly decrypts data signed with the command line
tools.
> >
> > The reason I do this is because the Smartcard (GPK8000) gives back the
raw
> > modulus and exponent which I then use to verify data signed by the card.
> > The
> > card modulus has to be reversed otherwise I get (BN) parse error. I also
> > set
> > padding off otherwise I get a (PKCS1_PAD) error. Now the decryption runs
> > without error except instead of recovering the 16 byte original data
from
> > the 128 byte signiture block I get a 128 byte block of rubbish.
> >
> > Any clues as to what I can try?
> >
> > thanks
> > bruce
> >
> > ----- Original Message -----
> > From: "Reddie, Steven" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Friday, March 09, 2001 11:03 AM
> > Subject: RE: How do I construct an instance of RSA using n & e
> >
> >
> > > You got it. Call RSA_new() to allocate and initialize the RSA struct,
> > the
> > > BN_bin2bn to generate the BIGNUM's. Something along the following
lines
> > > should do it:
> > > RSA* rsa = RSA_new();
> > > rsa->n = BN_bin2bn(modulus, modulus_size, NULL);
> > > rsa->e = BN_bin2bn(exponent, exponent_size, NULL);
> > >
> > > Regards,
> > >
> > > Steven
> > > --
> > > Steven Reddie <[EMAIL PROTECTED]>
> > > Senior Software Engineer
> > > Computer Associates Pty Ltd (Australia)
> > >
> > >
> > > > -----Original Message-----
> > > > From: bruce cartland [SMTP:[EMAIL PROTECTED]]
> > > > Sent: Friday, March 09, 2001 9:16 AM
> > > > To: [EMAIL PROTECTED]
> > > > Subject: How do I construct an instance of RSA using n & e
> > > >
> > > > I have n (the public modulus) and e (the public exponent). No
nicely
> > > > encoded data. Given those two values is there an API set to
construct
> > the
> > > > RSA (public key) structure? I'm guessing I'd have to create a BIGNUM
> > first
> > > > then ..? Nothing obvious in rsa.h. Would it be reasonable to create
a
> > new
> > > > RSA struct then set the pointers directly?
> > > > thanks
> > > >
> > > > bruce
> > > >
> > > >
> > > >
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slrsautl.c
