Microsoft rc2cryptoserviceprovider's negligence in encryption

Use rc2cryptoserviceprovider for encryption. In framework1.1, IV can use less than 8 bits. However, in Framework 2.0, IV must contain at least 8 bits. Otherwise, an exception is thrown! If the framework class library is reflected, an exception is added. If the length is less than 8 bits, an exception is thrown. ms has always been backward compatible, but isn't the encrypted data with less than 7 bits in framework1.1 used in Framework 2.0?

 

The followingCodeIt can be passed in Framework 1.1, but not in Framework 2.0. Pay attention to the IV length.

Using System;
Using System. IO;
Using System. text;
Using System. Security. cryptography;

Namespace Rc2cryptoserviceprovider_examples
{
Class Mymainclass1
{
Public   Static   Void Main ()
{

// Create a new instance of the rc2cryptoserviceprovider class
// And automatically generate a key and IV.
Rc2cryptoserviceprovider rc2csp =   New Rc2cryptoserviceprovider ();

Console. writeline ( " Valid key size is {0} bits. " , Rc2csp. effectivekeysize );

String Striv =   " 1234567 " ;
// Get the key and IV.
Byte [] Key = Rc2csp. Key;
Byte [] IV; // = Rc2csp. IV;
IV = Asciiencoding. ASCII. getbytes (striv );

// Get an encryptor.
Icryptotransform encryptor = Rc2csp. createencryptor (Key, IV );

// Encrypt the data as an array of encrypted bytes in memory.
Memorystream msencrypt =   New Memorystream ();
Cryptostream csencrypt =   New Cryptostream (msencrypt, encryptor, cryptostreammode. Write );

// Convert the data to a byte array.
String Original =   " Here is some data to encrypt. " ;
Byte [] Toencrypt = Encoding. ASCII. getbytes (original );

// Write all data to the crypto stream and flush it.
Csencrypt. Write (toencrypt, 0 , Toencrypt. Length );
Csencrypt. flushfinalblock ();

// Get the encrypted array of bytes.
Byte [] Encrypted = Msencrypt. toarray ();

/**/ /**/
/**/ //////////////////////////////////////// ///////////////
// This is where the data cocould be transmitted or saved.
/**/ /**/
/**/ //////////////////////////////////////// ///////////////

// Get a decryptor that uses the same key and IV as the encryptor.
Icryptotransform decryptor = Rc2csp. createdecryptor (Key, IV );

// Now decrypt the previusly encrypted message using the decryptor
// Obtained in the above step.
Memorystream msdecrypt =   New Memorystream (encrypted );
Cryptostream csdecrypt =   New Cryptostream (msdecrypt, decryptor, cryptostreammode. Read );

Byte [] Fromencrypt =   New   Byte [Toencrypt. Length];

// Read the data out of the crypto stream.
Csdecrypt. Read (fromencrypt, 0 , Toencrypt. Length );

// Convert the byte array back into a string.
String roundtrip = Encoding. ASCII. getstring (fromencrypt );

// Display the original data and the decrypted data.
Console. writeline ( " Original: {0} " , Original );
Console. writeline ( " Round trip: {0} " , Roundtrip );

Console. Readline ();
}
}
}