Assymetric Encryption

Two asymmetric algorithms

·         DSA [Digital Signature Algorithm]

·         RSA [Rivest, Shamir and Adleman]

 

Asymmetric encryption algorithms often are used to create Digital Signatures.

Typically, one key is made public, and the other key is kept private. If you encrypt a message with your private key, it can be decrypted only with your public key.

If you send another user a message encrypted with your private key, that user can verify that you sent the message by decrypting it with your public key.

 

Way to get Public/Privat pair:

 

Dim objDSA As New DSACryptoServiceProvider()

Private Key= objDSA.ToXmlString (True)

Public Key= objDSA.ToXmlString (False)

 

You can use the SignData method to generate a digital signature for a message.

The VerifyData method performs the opposite operation. You can use this method to verify that a message matches its digital signature.

 

Signing Data:

 

  Dim arrInput As Byte()

  Dim objDSA As DSACryptoServiceProvider

  Dim arrDigitalSignature As Byte()

 

  arrInput = System.Text.Encoding.Default.GetBytes ( txtInput.Text )

  objDSA = New DSACryptoServiceProvider()

  arrDigitalSignature = objDSA.SignData( arrInput )

  txtSignature.Text = System.Text.Encoding.Default.GetString ( arrDigitalSignature )

 

Verifying Data:

 

  Dim arrInput As Byte()

  Dim objDSA As DSACryptoServiceProvider

  Dim strPublicKey As String

  Dim arrDigitalSignature As Byte()

 

  arrInput = System.Text.Encoding.Default.GetBytes ( txtInput.Text )

  arrDigitalSignature = System.Text.Encoding.Default.GetBytes ( txtSignature.Text )

 

  objDSA = New DSACryptoServiceProvider() 

  bool res = objDSA.VerifyData( arrInput, arrDigitalSignature )

 

 

 

Thanks & Regards,

Arun Manglick

SMTS || Microsoft Technology Practice || Bridgestone - Tyre Link || Persistent Systems || 3023-6258

 

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