RSACryptoServiceProvider Encrypt and Decrypt

Question

Hi... I want to Encrypt and Decrypt a stream of data using the RSACryptoServiceProvider. But the problem is that it throws an error saying: Bad Length. Heard that there is a limit to the KeySize. How can I overcome it? Tried the overloaded constructor: RSACryptoServiceProvider RSA = new RSACryptoServiceProvider((int)dataStream.Length * 8); //dataStream a MemeoryStream object containing the data. But no use.. Any help? Regards Ganesh.

Dani Vuk · Answer

Hello I have problem when i tried to encrpyt XML file. The file is big araund 10 kb. I convert it bytes... when RSACryptoServiceProvider.Encrypt return me unknowvn error does someone have expirience with this or shuld i try to use another class provider. Thx for help I tried to send this reply several times but nothing happens. Dani

Muhammad Shakir · Answer

2 problems may occure. 1. data length is not same on both end. 2. RSA is used for small data like key (encryption/decryption)

jose salcedo · Answer

hello i have been reading your code its very useful but if i would like implement a mix with a simmetric algorithm Rijndael how can i do it i got this code but the Bad lenght error comes out: thanks for any help static byte[] Decrypt (RSA rsa byte[] input) { // by default this will create a 128 bits AES (Rijndael) object SymmetricAlgorithm sa = SymmetricAlgorithm.Create (); byte[] keyex = new byte [rsa.KeySize /8 ]; Buffer.BlockCopy (input 0 keyex 0 keyex.Length); RSAPKCS1KeyExchangeDeformatter def = new RSAPKCS1KeyExchangeDeformatter (rsa); byte[] key = def.DecryptKeyExchange (keyex); byte[] iv = new byte [sa.IV.Length]; Buffer.BlockCopy (input keyex.Length iv 0 iv.Length); ICryptoTransform ct = sa.CreateDecryptor (key iv); byte[] decrypt = ct.TransformFinalBlock (input keyex.Length + iv.Length input.Length - (keyex.Length + iv.Length)); return decrypt; }

subhasishweb · Answer

This is the proper code : ============================= public void abc(string StrInput) { CspParameters CspParam=new CspParameters(); CspParam.Flags = CspProviderFlags.UseMachineKeyStore; RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(CspParam); string PublicKey = RSA.ToXmlString(false); string PrivateKey = RSA.ToXmlString(true); Response.Write(PrivateKey); //Encryption RSACryptoServiceProvider RSA2 = new RSACryptoServiceProvider(); RSA2.FromXmlString(PrivateKey); byte[] EncryptedStrAsByte = RSA2.Encrypt(System.Text.Encoding.Unicode.GetBytes(StrInput)false); string EncryptedStrAsString = System.Text.Encoding.Unicode.GetString(EncryptedStrAsByte).ToString(); //return EncryptedStrAsString; Response.Write(EncryptedStrAsString); //Decryption RSACryptoServiceProvider RSA3 = new RSACryptoServiceProvider(CspParam); RSA3.FromXmlString(PublicKey); byte[] DecryptedStrAsByte = RSA3.Decrypt(System.Text.Encoding.Unicode.GetBytes(EncryptedStrAsString)false); string DecryptedStrAsString = System.Text.Encoding.Unicode.GetString(DecryptedStrAsByte).ToString(); //return DecryptedStrAsString; Response.Write( ); Response.Write(DecryptedStrAsString); }