Decryption can be handled in the same way; use CreateDecryptor instead of CreateEncryptor. The same key and initialization vector used to encrypt the file must be used to decrypt it. TripleDES uses three successive iterations of the DES algorithm. It can use either two or three 56-bit keys. Jun 06, 2017  The simplest way is to use a wrapper function that just converts the byte array to a string, encrypts it with your AESEncrypt function, and converts the string back to a byte array. You can find conversion functions for VB.net here. Edited to add: I think I got this wrong. It seems that a VB String is in Unicode format, and these translation functions convert it to/from a UTF8 byte array.

• 3des Decryption Vb.net
• 3des Decryption Vb.net Codes

3des Decryption Vb.net

This walkthrough shows you how to use the DESCryptoServiceProvider class to encrypt and decrypt strings using the cryptographic service provider (CSP) version of the Triple Data Encryption Standard (TripleDES) algorithm. The first step is to create a simple wrapper class that encapsulates the 3DES algorithm and stores the encrypted data as a base-64 encoded string. Then, that wrapper is used to securely store private user data in a publicly accessible text file.

You can use encryption to protect user secrets (for example, passwords) and to make credentials unreadable by unauthorized users. This can protect an authorized user's identity from being stolen, which protects the user's assets and provides non-repudiation. Encryption can also protect a user's data from being accessed by unauthorized users.

For more information, see Cryptographic Services.

Important

The Rijndael (now referred to as Advanced Encryption Standard [AES]) and Triple Data Encryption Standard (3DES) algorithms provide greater security than DES because they are more computationally intensive. For more information, see DES and Rijndael.

To create the encryption wrapper

1. Create the Simple3Des class to encapsulate the encryption and decryption methods.

2. Add an import of the cryptography namespace to the start of the file that contains the Simple3Des class.

3. In the Simple3Des class, add a private field to store the 3DES cryptographic service provider.

4. Add a private method that creates a byte array of a specified length from the hash of the specified key.

5. Add a constructor to initialize the 3DES cryptographic service provider.

   The key parameter controls the EncryptData and DecryptData methods.

6. Add a public method that encrypts a string.

7. Add a public method that decrypts a string.

   The wrapper class can now be used to protect user assets. In this example, it is used to securely store private user data in a publicly accessible text file.

To test the encryption wrapper

1. In a separate class, add a method that uses the wrapper's EncryptData method to encrypt a string and write it to the user's My Documents folder.

2. Add a method that reads the encrypted string from the user's My Documents folder and decrypts the string with the wrapper's DecryptData method.

3. Add user interface code to call the TestEncoding and TestDecoding methods.

4. Run the application.

   When you test the application, notice that it will not decrypt the data if you provide the wrong password.

   

See also

I'm trying to exchange encrypted data between my ASP.NET application and another developer's CF app using TripleDES.

Here's his CF code (fictitious key and IV of course):

Here's my VB.NET (I've left out exception handling, etc.):

We're getting different results.

3des Decryption Vb.net Codes

The obvious thing that comes to mind is that he's using Base64 to create the IV from the password, whereas I'm using ASCII - but if I do this

then .NET is not happy because it's getting a 6-byte array for the IV and it wants 8 bytes.

Any ideas what we're doing wrong - preferably changes I could make to my (VB.NET) code to make this work? Or failing that, a different approach that would work better between the two environments?

2 Answers

The default for CF seems to be 'DESede/ECB/PKCS5Padding' but in VB.NET they are 'DESede/CBC/PKCS7'. I am not sure why, but the two paddings (PKCS5 and PKCS7) seem to be compatible.

To get it to work, you either need to change the mode to 'ECB' on VB.NET side

.OR change the CF mode and IV to match the VB.NET defaults

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