Shahed Khan (MVP C#)

Here are some good Cryptography related resources.

Cryptography Overview
http://msdn2.microsoft.com/en-us/library/92f9ye3s.aspx

New and improved Security in the .Net Framework2.0
 http://msdn2.microsoft.com/en-us/library/aa480472.aspx the examples are very useful

Protect Private Data with the Cryptography Namespaces of the .NET Frameworkhttp://msdn.microsoft.com/msdnmag/issues/02/06/crypto/ should help you get an insight on .NET Cryptography essentials.

Walkthrough Creating a Cryptographic Application.
http://msdn2.microsoft.com/en-us/library/aa964697.aspx

Cryptographic Services
http://msdn2.microsoft.com/en-us/library/93bskf9z.aspx

Cryptographic Tasks

http://msdn2.microsoft.com/en-us/library/7yx4d854.aspx

Describes how to generate and manage keys and how to encrypt and decrypt data.

Describes how to generate and verify cryptographic signatures.

Describes how to generate and verify hash codes.

Describes how to help create a cryptographic scheme from the various cryptographic primitives.

Describes how to extend the .NET Framework cryptographic classes by creating a keyed hash algorithm class that implements the MD5 hash algorithm.

Provides links to reference and task-based documentation for XML encryption and digital signatures.

Describes how to use the managed data protection API (DPAPI) to encrypt and decrypt data.

Describes how to use hardware encryption devices with the .NET Framework.

XML Encryption and Digital Signatures
http://msdn2.microsoft.com/en-us/library/ms229749.aspx

How to: Encrypt XML Elements with Symmetric Keys

Describes how to encrypt an XML element using the Rijndael algorithm.

Describes how to decrypt an XML element that was encrypted using the Rijndael algorithm.

Describes how to encrypt an XML element using the RSA algorithm.

Describes how to decrypt an XML element using the RSA algorithm.

Describes how to encrypt an XML element using an X.509 certificate from a certificate store.

Describes how to decrypt an XML element using an X.509 certificate from a certificate store.

Describes how to sign an XML document using the RSA algorithm.

Describes how to verify an XML document using the RSA algorithm.

About System.Security.Cryptography.Pkcs
http://msdn2.microsoft.com/en-us/library/ms180945.aspx

Using System.Security.Cryptography.Pkcs
http://msdn2.microsoft.com/en-us/library/ms180955.aspx

Creates a CMS/PKCS #7 signed message. The message is signed by a single signer.

Creates a CMS/PKCS #7 signed message. The message is signed by multiple signers.

Creates a CMS/PKCS #7 signed message. The message is signed by a single signer. That signature is then countersigned by two other signers.

Creates a CMS/PKCS #7 enveloped message. The message is encrypted for a single recipient.

Creates a CMS/PKCS #7 enveloped message. The message is encrypted for multiple recipients.

Creates a CMS/PKCS #7 enveloped signed message. The message is first signed by a single signer and is then encrypted for a single recipient.

Contains additional programming tasks.