Re: Suggested additional constructor for RSACryptoServiceProvider

From: Steven Grayson [MSFT] (sgrayson_at_online.microsoft.com)
Date: 06/12/03 

Date: Thu, 12 Jun 2003 08:55:01 -0700

Since we're on the subject of the RSACryptoServiceProvider class, I thought
I would include here information that will be in the next release regarding
this class. Some folks stated they didn't know some of this information.

- default RSACryptoServiceProvider rsa = RSACryptoServiceProvider()
constructor
generates new RSA public/private transient key-pairs each time invoked.

- if rsa.PersistKeyInCsp = true is used, a random key container name,
prepended
with "CLR" is persisted

- overloaded RSACryptoServiceProvider rsa =
RSACryptoServiceProvider(CspParameters cp)
creates (or reuses an existing) a persistent key container with the name
specified
in cp.KeyContainerName

- for this overloaded constructor, if the only CspParameters field specified
is
KeyContainerName, the RSA key-pair generated (or re-used) is the key pair of
type AT_KEYEXCHANGE. CryptoAPI key containers using the MS CSPs can contain
two types of key-pairs (key spec): AT_KEYEXCHANGE and AT_SIGNATURE which the
WinCrypt.h header file defines as 1 and 2 respectively.

- although not clearly documented, it appears that the key type is specified
as
CspParameters.KeyNumber
with KeyNumber= 1 (AT_KEYEXCHANGE) and KeyNumber=2 (AT_SIGNATURE)
and with AT_EXCHANGE being the default.

- if a RSACryptoServiceProvider is instantiated twice, once with KeyNumber=1
and then
2, supplying the same cp.KeyContainerName, then the same CryptoAPI
keycontainer
will be populated with 2 sets of keys in the same named key container. (This
is
similar to the PSDK sample code for generating a key container with both
Signature
and Exchange key pairs). 

-- 
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"Pieter Philippaerts" <pieter@nospam.mentalis.org> wrote in message
news:u5mzBDBMDHA.3144@tk2msftngp13.phx.gbl...
> "Michel Gallant" <neutron@istar.ca> wrote in message
> > Currently with 1.0/1.1 .NET Framework classes,  RSACryptoServiceProvider
> > constructors support initializing with existing RSA credentials using
the
> CspParameters
> > argument.
> > I think it would be very useful to have a constructor supporting an
> > exported  public-key file argument. This would be very handy, for
example,
> > in using signature verification where end-users currently need to
populate
> > CspParameters explicitly with modulus and exponent properties.
>
> While we're at the subject of RSACryptoServiceProvider improvements, why
not
> implement the EncryptValue and DecryptValue methods? I'm still wondering
why
> MS didn't implement those in the first place...
>
> Regards,
> Pieter Philippaerts
>
>

Relevant Pages

  • RE: Using the Public Key embedded in the Assembly?
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    ... Then you install that, using sn -i into CryptoAPI keycontainer ... Solution is to specify the key type for RSA constructor like: ... > KeyPair.snk" some time back and installed into a machine key container on ... > each of these machines) and the public key is the same for each machine from ...
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    ... One of the things I discovered is the 'standard' RSA algorithms, ... I've more-or-less come to the conclusion that the RSACryptoServiceProvider ... >> passwords and other sensitive information is passed from the client back to ... >> a JavaScript RSA implementation that works with the RSACryptoServiceProvider. ...
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