public static string[] DecodeMnemonicFromEntropy(byte[] entropy, Wordlist wordList)
{
if (entropy == null || entropy.Length == 0)
{
throw new FormatException("Seed was null or empty.");
}
List <string> mnemonic = new List <string>();
if (entropy.Length % 4 > 0)
{
throw new FormatException("Seed must be multiples of 32 bits of entropy");
}
else if (entropy.Length < 8)
{
throw new FormatException("Seed must be at least 64 bits of entropy");
}
else if (entropy.Length > 124)
{
throw new FormatException("Seed must not exceed 992 bits of entropy");
}
// There's a reason to this double array madness...
BitArray entropyBitArray = new BitArray(BytesToBoolArray(entropy));
int checksumLengthBits = entropyBitArray.Length / 32;
Array entropyBits = Array.CreateInstance(typeof(bool), entropyBitArray.Length);
entropyBitArray.CopyTo(entropyBits, 0);
byte[] hash = SHA256.Create().ComputeHash(entropy);
BitArray hashBitArray = new BitArray(BytesToBoolArray(hash));
Array hashBits = Array.CreateInstance(typeof(bool), checksumLengthBits);
for (int i = 0; i < checksumLengthBits; i++)
{
bool bit = hashBitArray.Get(i);
hashBits.SetValue(bit, i);
}
Array concatBits = Array.CreateInstance(typeof(bool), entropyBits.Length + checksumLengthBits);
entropyBits.CopyTo(concatBits, 0);
hashBits.CopyTo(concatBits, entropyBits.Length);
int nwords = concatBits.Length / 11;
for (int i = 0; i < nwords; ++i)
{
// 11 bits per word (2048)
int index = 0;
for (int j = 0; j < 11; ++j)
{
index <<= 1;
bool bit = (bool)concatBits.GetValue((i * 11) + j);
if (bit)
{
index |= 0b1;
}
}
mnemonic.Add(wordList.GetWordAtIndex(index));
}
return(mnemonic.ToArray());
}
