Encrypt and decrypt strings using keys (C #)

The example shown on the video is played against the video.CodeThe test failed. After I searched the internet, I changed the test to succeeded. I don't know why the test was correct on the same code video as the video and my test failed, write it down for later use!

Code
///   <Summary> String encryption and decryption
///  
///   </Summary>
Public   Class Encrypt
{
Private Symmetricalgorithm MCSP;
Private   Const   String Civ =   " OO */^ FSa " ; // Key, which can only be 8 bits
Private   Const   String Ckey =   " F123 $ dew " ; // Initialization vector, which can only be 8 bits

Public Encrypt ()
{
MCSP =   New Descryptoserviceprovider ();
}

///   <Summary> Encrypted string
///  
///   </Summary>
///   <Param name = "value"> </param>
///   <Returns> </returns>
Public   String Encryptstring ( String Value)
{
Icryptotransform CT;
Memorystream MS;
Cryptostream Cs;
Byte [] BYT;
// Convert. frombase64string (ckey/CIV) is used in the video. However, if I use convert, errors always occur. What is wrong?
CT = MCSP. createencryptor (encoding. ASCII. getbytes (ckey), encoding. ASCII. getbytes (CIV ));
Byt = Encoding. utf8.getbytes (value );
MS =   New Memorystream ();
CS =   New Cryptostream (MS, CT, cryptostreammode. Write );
CS. Write (BYT, 0 , Byt. Length );
CS. flushfinalblock ();
CS. Close ();
Return Convert. tobase64string (Ms. toarray ());
}

///   <Summary> Decrypt string
///  
///   </Summary>
///   <Param name = "value"> </param>
///   <Returns> </returns>
Public   String Decryptstring ( String Value)
{
Icryptotransform CT;
Memorystream MS;
Cryptostream Cs;
Byte [] BYT;
CT = MCSP. createdecryptor (encoding. ASCII. getbytes (ckey), encoding. ASCII. getbytes (CIV ));
Byt = Convert. frombase64string (value );

MS = New memorystream ();
CS = New cryptostream (MS, CT, cryptostreammode. write);
CS. write (BYT, 0 , byt. length);
CS. flushfinalblock ();
CS. close ();

ReturnEncoding. utf8.getstring (Ms. toarray ());
}
}

 

Test code:

Static   Void Main ( String [] ARGs)
{
Console. Write ( " Enter the string to be encrypted: " );
String Str = Console. Readline ();
Console. writeline ( " After encryption: "   +   New Encrypt (). encryptstring (STR ));
Console. Readline ();

Console. Write ( " Enter the string to decrypt: " );
String Str2 = Console. Readline ();
Console. writeline ( " After decryption: "   +   New Encrypt (). decryptstring (str2 ));
Console. Readline ();
}

 

Test results: