/// <summary>
/// recover key from many different reader responses on same tag challenge
/// </summary>
/// <param name="uid"></param>
/// <param name="nt"></param>
/// <param name="nonces"></param>
/// <returns></returns>
public static ulong MfKey32(uint uid, uint nt, IEnumerable <Nonce> nonces)
{
var nonce = nonces.First();
nonces = nonces.Skip(1);
var p64 = Crypto1.PrngSuccessor(nt, 64);
var list = Crapto1.LfsrRecovery32(nonce.Ar ^ p64, 0);
var keys = new ConcurrentBag <ulong>();
Parallel.ForEach(list, s =>
{
var crapto1 = new Crapto1(s);
crapto1.LfsrRollbackWord();
crapto1.LfsrRollbackWord(nonce.Nr, true);
crapto1.LfsrRollbackWord(uid ^ nt);
var crypto1 = new Crypto1();
var allPass = nonces.All(n =>
{
crypto1.State = crapto1.State;
crypto1.Crypto1Word(uid ^ nt);
crypto1.Crypto1Word(n.Nr, true);
return(n.Ar == (crypto1.Crypto1Word() ^ p64));
});
if (allPass)
{
keys.Add(crapto1.Lfsr);
}
});
return(keys.Count == 1 ? keys.First() : ulong.MaxValue);
}
/// <summary>
/// recover key from reader response and tag response of one authentication sequence
/// </summary>
/// <param name="uid"></param>
/// <param name="nt"></param>
/// <param name="nr"></param>
/// <param name="ar"></param>
/// <param name="at"></param>
/// <returns></returns>
public static ulong MfKey64(uint uid, uint nt, uint nr, uint ar, uint at)
{
// Extract the keystream from the messages
var ks2 = ar ^ Crypto1.PrngSuccessor(nt, 64); // keystream used to encrypt reader response
var ks3 = at ^ Crypto1.PrngSuccessor(nt, 96); // keystream used to encrypt tag response
var revstate = Crapto1.LfsrRecovery64(ks2, ks3).First();
var crapto1 = new Crapto1(revstate);
crapto1.LfsrRollbackWord();
crapto1.LfsrRollbackWord();
crapto1.LfsrRollbackWord(nr, true);
crapto1.LfsrRollbackWord(uid ^ nt);
return(crapto1.Lfsr);
}
/// <summary>
/// recover key from 2 different reader responses on same tag challenge
/// </summary>
/// <param name="uid"></param>
/// <param name="nt"></param>
/// <param name="nr0"></param>
/// <param name="ar0"></param>
/// <param name="nr1"></param>
/// <param name="ar1"></param>
/// <returns>return ulong.MaxValue if key not found</returns>
public static ulong MfKey32(uint uid, uint nt, uint nr0, uint ar0, uint nr1, uint ar1)
{
var p64 = Crypto1.PrngSuccessor(nt, 64);
var list = Crapto1.LfsrRecovery32(ar0 ^ p64, 0);
var keys = new ConcurrentBag <ulong>();
Parallel.ForEach(list, s =>
{
var crapto1 = new Crapto1(s);
crapto1.LfsrRollbackWord();
crapto1.LfsrRollbackWord(nr0, true);
crapto1.LfsrRollbackWord(uid ^ nt);
var key = crapto1.Lfsr;
crapto1.Crypto1Word(uid ^ nt);
crapto1.Crypto1Word(nr1, true);
if (ar1 == (crapto1.Crypto1Word() ^ p64))
{
keys.Add(key);
}
});
return(keys.Count == 1 ? keys.First() : ulong.MaxValue);
}
