/// <summary>
/// Encodes a cash address
/// </summary>
/// <param name="scriptType">the bitcoin script type in byte format (P2PKH = 0x0, or P2SH = 0x8)</param>
/// <param name="hash">byte array representing address</param>
/// <param name="header">network - bitcoincash, bchtest, bchreg</param>
/// <returns>base32 encoded string with checksum and header</returns>
private static string EncodeWithHeaderAndChecksum(string header, byte scriptType, byte[] hash)
{
// calculate the version byte - in bits, 0 reserved, 1-4 address type, 4-7 size of hash
var versionByte = scriptType + GetHashSizeBits(hash);
// convert byte array from 8bits to 5, append prefix 0 bit and version byte
var base5 = ConvertBits(new[] { (byte)versionByte }.Concat(hash).ToArray(), 8, 5);
// generate checksum from base5 array
var checksumBytes = CreateChecksum(base5, header);
// append the checksum to the base5 array
var combined = base5.Concat(checksumBytes).ToArray();
// return address as base32 encoded with header
return(header + ":" + Base32Util.Encode(combined));
}
/// <summary>
/// Checks is a given cash address has correct checksum
/// </summary>
/// <param name="address">cash address to validate</param>
/// <param name="decoded">decoded address matching the cashAddress</param>
/// <returns>true if checksum is valid, false otherwise</returns>
public static bool ValidateChecksum(string address, DecodedBitcoinAddress decoded)
{
// split at the separator colon; format address in lower case
var pieces = address.ToLower().Split(':');
// trim the prefix (should be "bitcoincash", "bchtest", or "bchreg") - the first chunk separated by colon
var prefix = pieces[0];
// base32 decode the payload (second chunk)
var payload = Base32Util.Decode(pieces[1]);
// get start value for polymod
var startValue = GetPolyModStartValue(prefix);
// polymod on payload including checksum should be 0
return(PolyMod(payload, startValue) == 0);
}
/// <summary>
/// Decodes a CashAddress into prefix, type, and hash160
/// </summary>
/// <param name="address">Cash Address formatted address</param>
/// <returns>prefix, type, hash160 bytes</returns>
private static DecodedBitcoinAddress Decode(string address)
{
// split at the separator colon; format address in lower case
var pieces = address.ToLower().Split(':');
// trim the prefix (should be "bitcoincash" or "bchtest") - the first chunk separated by colon
var prefix = pieces[0];
// base32 decode the payload (second chunk)
var payload = Base32Util.Decode(pieces[1]);
// trim the checksum
var data = payload.Take(payload.Length - 8).ToArray();
// convert byte data from 5bit to 8bit
var payloadData = ConvertBits(data, 5, 8, true);
// version byte (and type) is determined by the first byte in the result
var versionByte = payloadData[0];
var type = GetType(versionByte);
// hash is the rest of the data after the version byte
var hash = payloadData.Skip(1).ToArray();
return(new DecodedBitcoinAddress(prefix, type, hash));
}
