SSCrypto from Objective C to C#

I am trying to encrypt below base64 string in objective c .. Now i need to decrypt the output of below code in C# ... Please advice simplest way as i don't want to install any libs at server.

Please advice how can convert encripted string back to base64 using C# .

Thanks My Objective c Code for encripting the base 64

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
SSCrypto *crypto;
NSString *password =@"abcdefghijklmnoqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnoqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyzabcdefghijklmnopqrstuvwzyz";

NSData *seedData1 = [password dataUsingEncoding:NSUTF8StringEncoding];
crypto = [[SSCrypto alloc] initWithSymmetricKey:seedData1];

NSString *base64String = @"SUkqAAgAAAARAP4ABAABAAAAAAAAAAABAwABAAAAsAQAAAEBAwABAAAAEAIAAAIBAwABAAAAAQAAAAMBAwABAAAABAAAAAYBAwABAAAAAAAAAAoBAwABAAAAAQAAABEBBAABAAAACgEAABIBAwABAAAAAQAAABUBAwABAAAAAQAAABYBAwABAAAAEAIAABcBBAABAAAA3yUAABoBBQABAAAA2gAAABsBBQABAAAA4gAAACUBBAABAAAAAAAAACgBAwABAAAAAgAAADEBAgAgAAAA6gAAAAAAAADIAAAAAQAAAMgAAAABAAAAQ29tcHJlc3NlZCB3aXRoIFBBTklOSSBJbWFnZSsAAAAmoy1xRBcev/r/LSUkbRxE+cRxGpEdF0Rw2EcNhHDIBcufR2+R0XZJjI6OIj5HjCPRHR9F0R8wCmRwXI6I+eROjiNxpEdkdEdl2R8ujTMMuy+R0R8j5HZvNo2yOzcXyOiPkdFzLsjxHGRwbC5lwJQaQRDaCchYbAxEREREREREREREREREREREREREREREREREI0BuRww+RIyPFw2MSnIccp0yY58fgxZ5EcKaVhJdx//pL0OQwm5EA///WlgnWSAb/+q9KEgt4X+961qgtKkZJCMH/XlnojiSvNBUkmSCPZBiQlT//iR7pdK0tgnwzep3zv//DLtrqmuLDodf/X7w2lasnCq7CWPf/0l2a6sIIRSVjoLFf9/3sMJ+jrkIjeTonRHRtE6N5A86ohEQtF0d6Ijol0IiIiIiIiIiIi0IiIiIiOIiIiIiIiIiIiIiIiIiIiIgwjtb8tBIhXABABA==";

[crypto setClearTextWithString:base64String];

NSData *cipherText = [crypto encrypt:@"aes256"];

NSLog(@"Cipher text: '%@' using %@", [cipherText encodeBase64WithNewlines:NO], @"aes256");

NSLog(@" ");
[ pool release];

Below is my C# code for Decryption

 public static string DecryptString(string base64StringToDecrypt, string passphrase)
        {
            //Set up the encry开发者_如何学Pythonption objects

            using (AesCryptoServiceProvider acsp = GetProvider(Encoding.Default.GetBytes(passphrase)))
            {
                byte[] RawBytes = Convert.FromBase64String(base64StringToDecrypt);
                ICryptoTransform ictD = acsp.CreateDecryptor();
              //  TripleDES.
                //RawBytes now contains original byte array, still in Encrypted state

                //Decrypt into stream
                MemoryStream msD = new MemoryStream(RawBytes, 0, RawBytes.Length);
                CryptoStream csD = new CryptoStream(msD, ictD, CryptoStreamMode.Read);
                //csD now contains original byte array, fully decrypted

                //return the content of msD as a regular string
                return (new StreamReader(csD)).ReadToEnd();
            }

private static AesCryptoServiceProvider GetProvider(byte[] key)
        {
            AesCryptoServiceProvider result = new AesCryptoServiceProvider();
            result.BlockSize = 128;
            result.KeySize = 128;
            result.Mode = CipherMode.CBC;
            result.Padding = PaddingMode.PKCS7;

            result.GenerateIV();
            result.IV = new byte[] {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};

            byte[] RealKey = GetKey(key, result);
            result.Key = RealKey;
           // result.IV = RealKey;
            return result;
        }

        private static byte[] GetKey(byte[] suggestedKey, SymmetricAlgorithm p)
        {
            byte[] kRaw = suggestedKey;
            List<byte> kList = new List<byte>();

            for (int i = 0; i < p.LegalKeySizes[0].MinSize; i += 8)
            {
                kList.Add(kRaw[(i / 8) % kRaw.Length]);
            }
            byte[] k = kList.ToArray();
            return k;
        }

Please advice if anything is missing or if i have done something gross wrong .. I have lost more than 2 days in searching.

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You can do this easily with the AesManaged class. See:

http://msdn.microsoft.com/en-us/library/system.security.cryptography.aesmanaged.aspx