private static SaltParseException InternalTryParseSalt(string hashedPasswordString, out SaltWithParameters saltWithParameters,
out string hashedPassword)
{
saltWithParameters = null;
hashedPassword = null;
ulong n;
uint r, p, hashLengthBytes;
var components = hashedPasswordString.Split('$');
if (components.Length != 8)
return new SaltParseException("Expected 8 dollar-sign ($) delimited salt components");
if (components[0] != "" || components[1] != "scrypt")
return new SaltParseException("Expected $scrypt$");
if (!ulong.TryParse(components[2], out n))
return new SaltParseException("Failed to parse N parameter");
if (!uint.TryParse(components[3], out r))
return new SaltParseException("Failed to parse r parameter");
if (!uint.TryParse(components[4], out p))
return new SaltParseException("Failed to parse p parameter");
if (!uint.TryParse(components[5], out hashLengthBytes))
return new SaltParseException("Failed to parse hashLengthBytes parameter");
var saltBytes = Convert.FromBase64String(components[6]);
var parameters = new ScryptParameters(n, r, p, hashLengthBytes, (uint)saltBytes.Length);
saltWithParameters = new SaltWithParameters(saltBytes, parameters);
hashedPassword = components[7];
return null;
}
/// <summary>The 'raw' scrypt key-derivation function.</summary>
/// <param name="password">The password bytes to generate the key based upon.</param>
/// <param name="saltWithParameters">The salt and parameters to use for the generation.</param>
public static byte[] DeriveKey(byte[] password, SaltWithParameters saltWithParameters)
{
var result = new byte[saltWithParameters.Parameters.HashLengthBytes];
LibScrypt.Scrypt(password, saltWithParameters.Salt, saltWithParameters.Parameters.N,
saltWithParameters.Parameters.R, saltWithParameters.Parameters.P,
result);
return result;
}
public static void Parse(string hashedPasswordString, out SaltWithParameters saltWithParameters, out string hashedPassword)
{
var error = InternalTryParseSalt(hashedPasswordString, out saltWithParameters, out hashedPassword);
if (error != null)
{
throw error;
}
}
public static string Create(SaltWithParameters saltWithParameters, string hashedPassword)
{
if (saltWithParameters == null) throw new ArgumentNullException("saltWithParameters");
var builder = new StringBuilder();
builder.Append("$scrypt$");
builder.Append(saltWithParameters.Parameters.N);
builder.Append("$");
builder.Append(saltWithParameters.Parameters.R);
builder.Append("$");
builder.Append(saltWithParameters.Parameters.P);
builder.Append("$");
builder.Append(saltWithParameters.Parameters.HashLengthBytes);
builder.Append("$");
builder.Append(Convert.ToBase64String(saltWithParameters.Salt));
builder.Append("$");
builder.Append(hashedPassword);
return builder.ToString();
}
private static string HashPassword(string password, SaltWithParameters saltWithParameters, Encoding passwordEncoding)
{
var hashBytes = DeriveKey(passwordEncoding.GetBytes(password), saltWithParameters);
var hashString = Convert.ToBase64String(hashBytes);
return HashedPasswordString.Create(saltWithParameters, hashString);
}
public static string HashPasswordUtf8(string password, SaltWithParameters saltWithParameters)
{
return HashPassword(password, saltWithParameters, Encoding.UTF8);
}
public static string HashPassword(SecureString password, SaltWithParameters saltWithParameters)
{
var hashBytes = DeriveKey(password, saltWithParameters);
var hashString = Convert.ToBase64String(hashBytes);
return HashedPasswordString.Create(saltWithParameters, hashString);
}
public static bool TryParse(string hashedPasswordString, out SaltWithParameters saltWithParameters, out string hashedPassword)
{
var error = InternalTryParseSalt(hashedPasswordString, out saltWithParameters, out hashedPassword);
return error == null;
}
