//validates the checksum
private static bool ValidateChecksum(IChecksum16 checksum, byte[] key)
{
var sum = BitConverter.ToUInt16(key, key.Length - 2);
var keyBytes = new byte[key.Length - 2];
Buffer.BlockCopy(key, 0, keyBytes, 0, keyBytes.Length);
return(sum == checksum.Compute(keyBytes));
}
/// <summary>
/// Generate a key based on the given seed.
/// </summary>
/// <param name="seed">The seed value to generate the key from.</param>
/// <returns>A licensing key.</returns>
public string Generate(uint seed)
{
var data = new byte[(_baseKeys.Length * 4) + 4];
// add seed
data[0] = (byte)(seed & 0xFF);
data[1] = (byte)(seed >> 8);
data[2] = (byte)(seed >> 16);
data[3] = (byte)(seed >> 24);
//which hash function to use
var hashOffset = 0;
for (var i = 0; i < _baseKeys.Length; i++)
{
var digit = seed ^ _baseKeys[i];
var hval = _hashFunctions[hashOffset++].Compute((BitConverter.GetBytes(digit)));
data[4 + (4 * i)] = (byte)(hval & 0xFF);
data[5 + (4 * i)] = (byte)(hval >> 8);
data[6 + (4 * i)] = (byte)(hval >> 16);
data[7 + (4 * i)] = (byte)(hval >> 24);
hashOffset %= _hashFunctions.Count;
}
var checksum = _checksum.Compute(data);
var key = new byte[data.Length + 2];
Buffer.BlockCopy(data, 0, key, 0, data.Length);
key[key.Length - 2] = (byte)(checksum & 0xFF);
key[key.Length - 1] = (byte)(checksum >> 8);
var ret = Base32.ToBase32(key);
if (Spacing > 0)
{
var count = (ret.Length / Spacing);
if (ret.Length % Spacing == 0)
{
--count;
}
for (var i = 0; i < count; i++)
{
ret = ret.Insert(Spacing + (i * Spacing + i), "-");
}
}
return(ret);
}
