/// <summary>
/// </summary>
/// <param name="payload"></param>
/// <param name="sideKey"></param>
/// <param name="root"></param>
/// <returns>(message,nextRoot)</returns>
public Tuple <string, string> DecodeMessage(string payload, string sideKey, string root)
{
if (string.IsNullOrEmpty(sideKey))
{
sideKey = "999999999999999999999999999999999999999999999999999999999999999999999999999999999";
}
var payloadTrits = Converter.ToTrits(payload);
var sideKeyTrits = Converter.ToTrits(sideKey);
var rootTrits = Converter.ToTrits(root);
ICurl curl = new Curl(SpongeFactory.Mode.CURLP27);
// parse
var result = Pascal.Decode(payloadTrits);
var index = (int)result.Item1;
var indexEnd = result.Item2;
var tempTrits = new sbyte[payloadTrits.Length - indexEnd];
Array.Copy(payloadTrits, indexEnd, tempTrits, 0, tempTrits.Length);
result = Pascal.Decode(tempTrits);
var messageLength = (int)result.Item1;
var messageLengthEnd = result.Item2;
var nextRootStart = indexEnd + messageLengthEnd;
var messageStart = nextRootStart + Constants.HashLength;
var messageEnd = messageStart + messageLength;
curl.Absorb(sideKeyTrits);
curl.Absorb(rootTrits);
if (messageLength > payloadTrits.Length)
{
throw new ArgumentOutOfRangeException();
}
curl.Absorb(payloadTrits, 0, nextRootStart);
MaskHelper.UnMaskSlice(payloadTrits, nextRootStart, messageStart - nextRootStart, curl);
MaskHelper.UnMaskSlice(payloadTrits, messageStart, messageEnd - messageStart, curl);
var pos = messageEnd;
MaskHelper.UnMaskSlice(payloadTrits, pos, Constants.MessageNonceLength, curl);
pos += Constants.HashLength / 3;
var hmac = new sbyte[Constants.HashLength];
Array.Copy(curl.Rate, hmac, Constants.HashLength);
var security = HashHelper.CheckSumSecurity(hmac);
MaskHelper.UnMaskSlice(payloadTrits, pos, payloadTrits.Length - pos, curl);
if (security == 0)
{
// InvalidHash
curl.Reset();
throw new ApplicationException();
}
var sigEnd = pos + security * Constants.KeyLength;
HashHelper.DigestBundleSignature(hmac, payloadTrits, pos, sigEnd - pos, curl);
Array.Copy(curl.Rate, hmac, Constants.HashLength);
curl.Reset();
pos = sigEnd;
tempTrits = new sbyte[payloadTrits.Length - pos];
Array.Copy(payloadTrits, pos, tempTrits, 0, tempTrits.Length);
result = Pascal.Decode(tempTrits);
curl.Absorb(hmac);
if (result.Item1 != 0)
{
// get address lite
Array.Copy(curl.Rate, hmac, Constants.HashLength);
pos += result.Item2;
var sibEnd = pos + (int)result.Item1;
var siblings = new sbyte[sibEnd - pos];
Array.Copy(payloadTrits, pos, siblings, 0, siblings.Length);
curl.Reset();
MerkleTree.Root(hmac, siblings, index, curl);
}
if (!curl.Rate.SequenceEqual(rootTrits))
{
// InvalidSignature
curl.Reset();
throw new ApplicationException();
}
var message = Converter.ToTrytes(payloadTrits, messageStart, messageLength);
var nextRoot = Converter.ToTrytes(payloadTrits, nextRootStart, Constants.HashLength);
return(new Tuple <string, string>(message, nextRoot));
}
private sbyte[] CreateMaskedPayload(
sbyte[] seedTrits, sbyte[] messageTrits,
sbyte[] keyTrits, sbyte[] rootTrits,
sbyte[] siblingsTrits, sbyte[] nextRootTrits,
int start, int index, int security)
{
ICurl curl = new Curl(SpongeFactory.Mode.CURLP27);
ICurl encrCurl = new Curl(SpongeFactory.Mode.CURLP27);
var hammingNonce = new HammingNonce(SpongeFactory.Mode.CURLP27);
var minLength = GetPayloadMinLength(messageTrits.Length, siblingsTrits.Length, index, security);
var payloadLength = (int)TritsHelper.RoundThird(minLength);
var payload = new sbyte[payloadLength];
// Creates a signed, encrypted payload from a message
// generate the key and the get the merkle tree hashes
var messageLength = messageTrits.Length;
var indexP = Pascal.EncodedLength(index);
var messageP = Pascal.EncodedLength(messageLength);
var siblingsLength = siblingsTrits.Length;
var siblingsCount = siblingsTrits.Length / Constants.HashLength;
var siblingsPascalLength = Pascal.EncodedLength(siblingsCount);
var signatureLength = security * Constants.KeyLength;
var nextRootStart = indexP + messageP;
var nextEnd = nextRootStart + nextRootTrits.Length;
var messageEnd = nextRootStart + Constants.HashLength + messageLength;
var nonceEnd = messageEnd + Constants.MessageNonceLength;
var signatureEnd = nonceEnd + signatureLength;
var siblingsPascalEnd = signatureEnd + siblingsPascalLength;
var siblingsEnd = siblingsPascalEnd + siblingsLength;
encrCurl.Absorb(keyTrits);
encrCurl.Absorb(rootTrits);
var trits = new sbyte[indexP];
Pascal.Encode(index, trits);
Array.Copy(trits, 0, payload, 0, indexP);
trits = new sbyte[messageP];
Pascal.Encode(messageLength, trits);
Array.Copy(trits, 0, payload, indexP, messageP);
encrCurl.Absorb(payload, 0, nextRootStart);
Array.Copy(nextRootTrits, 0, payload, nextRootStart, nextRootTrits.Length);
Array.Copy(messageTrits, 0, payload, nextEnd, messageTrits.Length);
MaskHelper.MaskSlice(payload, nextRootStart, messageEnd - nextRootStart, encrCurl);
Array.Copy(encrCurl.State, curl.State, encrCurl.State.Length);
hammingNonce.Search(security, 0, Constants.HashLength / 3, curl);
Array.Copy(curl.State, 0, payload, messageEnd, Constants.MessageNonceLength);
MaskHelper.MaskSlice(payload, messageEnd, nonceEnd - messageEnd, encrCurl);
curl.Reset();
var subseed = HashHelper.Subseed(seedTrits, start + index, curl);
Array.Copy(subseed, 0, payload, nonceEnd, subseed.Length);
curl.Reset();
HashHelper.Key(payload, nonceEnd, signatureEnd - nonceEnd, security, curl);
curl.Reset();
HashHelper.Signature(encrCurl.Rate, payload, nonceEnd, signatureEnd - nonceEnd, curl);
curl.Reset();
trits = new sbyte[siblingsPascalLength];
Pascal.Encode(siblingsCount, trits);
Array.Copy(trits, 0, payload, signatureEnd, siblingsPascalLength);
Array.Copy(siblingsTrits, 0, payload, siblingsPascalEnd, siblingsLength);
MaskHelper.MaskSlice(payload, nonceEnd, siblingsEnd - nonceEnd, encrCurl);
encrCurl.Reset();
return(payload);
}
