Thank you Matt!
Ron
From: Matthew S.
Hamrick [mailto:mhamrick@cryptonomicon.net]
Sent: Thursday, August 17, 2006
3:09 AM
To: Ron Teitelbaum
Subject: Re: [Cryptography Team]
Help with RSA
Hey Ron...
I haven't been looking too closely at the official crypto source, so I
can't say for sure. But from the sound of it, maybe it's the message encoding
scheme for the RSA signature. There are two main encoding schemes: PKCS#1 and
OAEP, though PKCS#1 now includes OAEP as an option. There's also ISO9697, but
I've never seen it used in conjunction with X.509. If this is the encoding
scheme, then it can be found in the ALGO oid in the SubjectPublicKeyInfo
portion of the cert.
Hope this helps.
-Cheers
-Matt H.
On Aug 16, 2006, at 8:21 PM, Ron Teitelbaum wrote:
Hello All,
I’m working
on SSL / TLS implementation in Squeak and I need some help understanding RSA.
It appears
that our RSA implementation has an encodingParameter. I see what it’s
doing but now I’m confused and was hoping that someone could explain this to me.
I see that
the parameter is needs to be the same for encrypting and decrypting, or it
doesn’t work.
My question
is how is this stored on a certificate?
Here is the
MS Export format http://msdn.microsoft.com/library/default.asp?url=/library/en-us/seccrypto/security/private_key_blobs.asp
Field |
Description |
blobheader |
A BLOBHEADER structure as described in a previous section. The
bType field must always have a
value of PRIVATEKEYBLOB. |
rsapubkey |
A RSAPUBKEY structure as described in Public
Key BLOBs. The magic field
must always have a value of 0x32415352 ("RSA2"). |
modulus |
The modulus. This has a value of
"prime1 * prime2" and is often known as "n". |
prime1 |
Prime number 1, often known as
"p". |
prime2 |
Prime number 2, often known as
"q". |
exponent1 |
Exponent 1. This has a numeric
value of "d mod (p - 1)". |
exponent2 |
Exponent 2. This has a numeric
value of "d mod (q - 1)". |
coefficient |
Coefficient. This has a numeric
value of "(inverse of q) mod p". |
privateExponent |
Private exponent, often known as
"d". |
I also noticed that : http://en.wikipedia.org/wiki/RSA
For reasons of efficiency sometimes a
different form of the private key
(including CRT parameters) is
stored:
Does
this mean that the parameter is the coefficient? Is the CRT parameter the
encoding parameter? Any help would be very much appreciated, I’m having
trouble understanding the differences, and how the parameter is supposed to be
used.
Thanks!
Ron
Teitelbaum
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