/// <include file='doc\PasswordDeriveBytes.uex' path='docs/doc[@for="PasswordDeriveBytes.CryptDeriveKey"]/*' />
public byte[] CryptDeriveKey(String algname, String alghashname, int keySize, byte[] rgbIV)
{
int hr;
int algid;
int algidhash;
int dwFlags = 0;
if (keySize < 0)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_InvalidKeySize"));
}
if (_hCSP == IntPtr.Zero)
{
hr = _AcquireCSP(_cspParams, ref _hCSP);
if (_hCSP == IntPtr.Zero)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_CSP_CouldNotAcquire"));
}
}
// Convert password to UTF8 string
byte[] rgbPwd = (new UTF8Encoding(false)).GetBytes(_strPassword);
// Form the correct dwFlags
dwFlags |= (keySize << 16);
algidhash = CryptoConfig.MapNameToCalg(alghashname);
if (algidhash == 0)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_PasswordDerivedBytes_InvalidAlgorithm"));
}
algid = CryptoConfig.MapNameToCalg(algname);
if (algid == 0)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_PasswordDerivedBytes_InvalidAlgorithm"));
}
// Validate the rgbIV array
SymmetricAlgorithm symAlg = (SymmetricAlgorithm)CryptoConfig.CreateFromName(algname);
if (symAlg == null)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_PasswordDerivedBytes_InvalidAlgorithm"));
}
if (rgbIV == null || rgbIV.Length != symAlg.BlockSize / 8)
{
throw new CryptographicException(Environment.GetResourceString("Cryptography_PasswordDerivedBytes_InvalidIV"));
}
byte[] rgbKey = _CryptDeriveKey(_hCSP, algid, algidhash, rgbPwd, dwFlags, rgbIV);
GC.KeepAlive(this);
return(rgbKey);
}