/// <summary>
/// Creates secure password based on the predefined input.
/// Hash algorithm must implement IHash interface and choosen algorithm
/// will determine the size of password returned.
/// </summary>
/// <param name="input">Input as string. It's called predefined input.</param>
/// <param name="hashCrypto">Concrete hash algorithm that implements IHash interface.</param>
/// <param name="iteration">Iteration count.</param>
/// <returns>Random password in bytes.</returns>
/// <exception cref="ArgumentNullException">'input' cannot be null/empty.</exception>
/// <exception cref="ArgumentNullException">'hashCrypto' cannot be null.</exception>
/// <exception cref="ArgumentOutOfRangeException">'iteration' is invalid.</exception>
public static byte[] CreateSecurePassword(string input, IHashCrypto hashCrypto, int iteration = 10000)
{
if (String.IsNullOrEmpty(input))
{
throw new ArgumentNullException(nameof(input));
}
if (hashCrypto == null)
{
throw new ArgumentNullException(nameof(hashCrypto));
}
if (iteration < 5000)
{
throw new ArgumentOutOfRangeException(nameof(iteration), "Min value for iteration is 5000.");
}
byte[] data = null;
try
{
byte[] salt = hashCrypto.GetHashBytes(input);
using (Rfc2898DeriveBytes generator = new Rfc2898DeriveBytes(input, salt, iteration))
{
data = generator.GetBytes(hashCrypto.HashSize / 8);
}
}
catch { data = null; }
return(data);
}
/// <summary>
/// Injectable constructor. Used commonly for dependency injection.
/// </summary>
/// <param name="hash">Concreate implementation of IHash interface.</param>
public HashCrypto(IHashCrypto hash)
{
_hash = hash;
if (_hash == null)
{
_hash = new SHA256Crypto();
}
}
/// <summary>
/// Compares 2 data using algorithm that implements IHashCrypto interface.
/// </summary>
/// <param name="data1">Data 1.</param>
/// <param name="data2">Data 2.</param>
/// <param name="hash">Hash algorithm that implements IHashCrypto interface.</param>
/// <returns>Returs true if both are same, otherwise false.</returns>
/// <exception cref="ArgumentNullException">First data cannot be null.</exception>
/// <exception cref="ArgumentNullException">Second data cannot be null.</exception>
/// <exception cref="ArgumentNullException">Hash algorithm cannot be null.</exception>
public static bool CompareHashes(byte[] data1, byte[] data2, IHashCrypto hash)
{
if (data1 == null)
{
throw new ArgumentNullException(nameof(data1), "First data cannot be null.");
}
if (data2 == null)
{
throw new ArgumentNullException(nameof(data2), "Second data cannot be null.");
}
if (hash == null)
{
throw new ArgumentNullException(nameof(hash), "Hash algorithm cannot be null.");
}
if (data1.Length != data2.Length)
{
return(false);
}
byte[] hashedData1 = null;
byte[] hashedData2 = null;
try
{
hashedData1 = hash.GetHashBytes(data1);
}
catch { hashedData1 = hashedData1 != null ? null : hashedData1; }
try
{
hashedData2 = hash.GetHashBytes(data2);
}
catch { hashedData2 = hashedData2 != null ? null : hashedData2; }
if (hashedData1 == null || hashedData2 == null)
{
return(false);
}
for (int i = 0; i < hashedData1.Length; i++)
{
if (hashedData1[i] != hashedData2[i])
{
return(false);
}
}
return(true);
}
/// <summary>
/// Main constructor. If no parameter passed, SHA256Crypto will be used.
/// </summary>
public HashCrypto()
{
_hash = new SHA256Crypto();
}