Saving encrypted string to database

[tcstom]

Hi,

I've written an encryption/decryption class that uses the methods below to decrypt and encrypt strings. This works fine, until I save the encrypted string to my SQL Server database. It saves in the database like this: '??????????????????' and cannot then be decrypted. I assume it's because I'm using Unicode encoding in my encryption/decryption methods, but if I change it to ASCII encoding the DesDecrypt method won't work. Can anyone help?

public static string DesEncrypt(string stringToEncrypt, string hashString)
{
	byte[] data = ConvertStringToByteArray(stringToEncrypt);
	string pws = hashString;
	System.Security.Cryptography.PasswordDeriveBytes db = new System.Security.Cryptography.PasswordDeriveBytes(pws, new byte[0]);
	byte[] m_bDESKey= db.GetBytes(16);
	TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
	des.Mode = CipherMode.CBC;
	byte[] m_bDESIV = System.Text.UnicodeEncoding.Unicode.GetBytes(hashString);
	MemoryStream ms = new MemoryStream(4096);
	CryptoStream encStream = new CryptoStream(ms, des.CreateEncryptor(KEY192, IV192), CryptoStreamMode.Write);
	encStream.Write(data,0,data.Length);
	encStream.FlushFinalBlock();
	//calculate the length of the encrypted data
	byte[] bResult = new byte[ms.Position];
	ms.Position = 0;
	ms.Read(bResult, 0, bResult.Length) ;
	encStream.Close();
	return System.Text.UnicodeEncoding.Unicode.GetString(bResult);
}

public static string DesDecrypt(string stringToDeCrypt, string hashString)
{
	byte[] data = ConvertStringToByteArray(stringToDeCrypt);
	string pws = hashString;
	System.Security.Cryptography.PasswordDeriveBytes db = new System.Security.Cryptography.PasswordDeriveBytes(pws, new byte[0]);
	byte[] m_bDESKey= db.GetBytes(16);
	TripleDESCryptoServiceProvider des = new TripleDESCryptoServiceProvider();
	des.Mode = CipherMode.CBC;
	byte[] m_bDESIV = System.Text.UnicodeEncoding.Unicode.GetBytes(hashString);
	MemoryStream ms = new MemoryStream(data.Length);
	CryptoStream encStream = new CryptoStream(ms, des.CreateDecryptor(KEY192, IV192), CryptoStreamMode.Read);
	ms.Write(data,0,data.Length);
	ms.Position = 0;
	string strResult = new StreamReader(encStream).ReadToEnd();
	encStream.Close();
	return strResult;
}

private static Byte[] ConvertStringToByteArray(String s)
{
	Byte[] returnValue = System.Text.UnicodeEncoding.Unicode.GetBytes(s);
	return returnValue;
}

 

[rchandr3]

Ideally you should post this in SQL server forum. There is something called Collation. Based on the Collation type you set on the field of the table, the value will get stored. This is the problem... Check with your DBA and they will provide a solution based on the data you save.

Cheers,

Ravi

 

[tcstom]

Thanks, but it's OK. (Good job, because I am my own DBA and I didn't know the answer!) I've found a method that uses UTF8 encoding. Here's the code if anyone's interested.

private static readonly string _key = "testing";

private static string Key
{
	get {return _key;}
}

public static string Encrypt(string toEncrypt, bool useHashing)
{
	byte[] keyArray;
	byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(toEncrypt);

	if (useHashing)
	{
		MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
		keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(Key));
		hashmd5.Clear();
	}
	else
	{
		keyArray = UTF8Encoding.UTF8.GetBytes(Key);
	}

	TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
	tdes.Key = keyArray;
	tdes.Mode = CipherMode.ECB;
	tdes.Padding = PaddingMode.PKCS7;

	ICryptoTransform cTransform = tdes.CreateEncryptor();
	byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
	tdes.Clear();

	return Convert.ToBase64String(resultArray, 0, resultArray.Length);
}

public static string Decrypt(string cipherString, bool useHashing)
{
	byte[] keyArray;
	byte[] toEncryptArray = Convert.FromBase64String(cipherString);

	if (useHashing)
	{
		MD5CryptoServiceProvider hashmd5 = new MD5CryptoServiceProvider();
		keyArray = hashmd5.ComputeHash(UTF8Encoding.UTF8.GetBytes(Key));
		hashmd5.Clear();
	}
	else
	{
		keyArray = UTF8Encoding.UTF8.GetBytes(Key);
	}

	TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
	tdes.Key = keyArray;
	tdes.Mode = CipherMode.ECB;
	tdes.Padding = PaddingMode.PKCS7;

	ICryptoTransform cTransform = tdes.CreateDecryptor();
	byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);          
	tdes.Clear();

	return UTF8Encoding.UTF8.GetString(resultArray);
}