/// <summary>
/// The checksum is a substring of the binary representation of the SHA256 hash of entropy.
/// For every four bytes of entropy, one additional bit of the hash is used.
/// </summary>
/// <param name="entropy"></param>
/// <returns></returns>
private static string GetChecksum(ReadOnlyByteSequence entropy)
{
var hash = entropy.Sha256();
var bits = (int)entropy.Length * 8;
var cs = bits / 32;
var sb = new StringBuilder();
foreach (var b in hash.Span)
{
sb.Append(Convert.ToString(b, 2).PadLeft(8, '0'));
cs -= 8;
if (cs <= 0)
{
break;
}
}
if (cs < 0)
{
sb.Length += cs;
}
return(sb.ToString());
}
/// <summary>
/// Computes RIPEMD160 of SHA256 of data: RIPEMD160(SHA256(data))
/// </summary>
/// <param name="data">Input: bytes to be hashed.</param>
/// <param name="hash">Output: RIPEMD160 of SHA256 of data.</param>
public static void Hash160(this ReadOnlyByteSequence data, ByteSpan hash)
{
var h = data.Sha256();
Ripemd160(h.Span, hash);
}