public static KeyFinderResult <TKey> FindBest <TKey>(
string ciphertext,
IKeyedCipher <TKey> cipher,
IKeySpaceSource <TKey> keySpace,
ISpeculativePlaintextRanker speculativePlaintextRanker,
Action <KeyFinderResult <TKey> > onBetterResultFound = null,
CancellationToken cancellationToken = default(CancellationToken)
)
{
if (ciphertext == null)
{
throw new ArgumentNullException(nameof(ciphertext));
}
if (cipher == null)
{
throw new ArgumentNullException(nameof(cipher));
}
if (keySpace == null)
{
throw new ArgumentNullException(nameof(keySpace));
}
if (speculativePlaintextRanker == null)
{
throw new ArgumentNullException(nameof(speculativePlaintextRanker));
}
KeyFinderResult <TKey> best = null;
object syncRoot = new object();
Parallel.ForEach(
keySpace.GetKeys(),
new ParallelOptions {
CancellationToken = cancellationToken
},
key =>
{
string speculativePlaintext = cipher.Decrypt(ciphertext, key);
double rank = speculativePlaintextRanker.Classify(speculativePlaintext);
if (rank > (best?.Rank ?? 0))
{
lock (syncRoot)
{
if (rank > (best?.Rank ?? 0))
{
best = new KeyFinderResult <TKey>(key, speculativePlaintext, rank);
onBetterResultFound?.Invoke(best);
}
}
}
}
);
return(best);
}
public static void FindAboveThreshold <TKey>(
string ciphertext,
IKeyedCipher <TKey> cipher,
IKeySpaceSource <TKey> keySpace,
ISpeculativePlaintextRanker speculativePlaintextRanker,
Action <KeyFinderResult <TKey> > onImmediateResultFound,
double threshold = 0.9,
CancellationToken cancellationToken = default(CancellationToken)
)
{
if (ciphertext == null)
{
throw new ArgumentNullException(nameof(ciphertext));
}
if (cipher == null)
{
throw new ArgumentNullException(nameof(cipher));
}
if (keySpace == null)
{
throw new ArgumentNullException(nameof(keySpace));
}
if (speculativePlaintextRanker == null)
{
throw new ArgumentNullException(nameof(speculativePlaintextRanker));
}
if (threshold < 0 || threshold > 1)
{
throw new ArgumentOutOfRangeException(nameof(threshold));
}
if (onImmediateResultFound == null)
{
throw new ArgumentNullException(nameof(onImmediateResultFound));
}
Parallel.ForEach(
keySpace.GetKeys(),
new ParallelOptions {
CancellationToken = cancellationToken
},
key =>
{
string speculativePlaintext = cipher.Decrypt(ciphertext, key);
double rank = speculativePlaintextRanker.Classify(speculativePlaintext);
if (rank >= threshold)
{
onImmediateResultFound(new KeyFinderResult <TKey>(key, speculativePlaintext, rank));
}
}
);
}
