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How do I sign a TransactionHex with SeedHex using secp256k1 in C# with Bouncy Castle?

I have this nodejs snippet which I want to implement in C#.
The SignTransaction function takes in a seedHex string (length: 64) and a TransactionHex string, a signature is created using secp256k1 algorithm and appended to the end of the TransactionHex.
const sha256 = require('sha256');
const EC = require('elliptic').ec;
const ec = new EC("secp256k1");
// Serialize a number into an 8-byte array. This is a copy/paste primitive, not worth
// getting into the details.
function uvarint64ToBuf (uint) {
const result = [];
while (uint >= 0x80) {
result.push((uint & 0xFF) | 0x80);
uint >>>= 7;
}
result.push(uint | 0);
return new Buffer(result);
}
// Sign transaction with seed
function signTransaction (seed, txnHex) {
const privateKey = ec.keyFromPrivate(seed);
const transactionBytes = new Buffer(txnHex, 'hex');
const transactionHash = new Buffer(sha256.x2(transactionBytes), 'hex');
const signature = privateKey.sign(transactionHash);
const signatureBytes = new Buffer(signature.toDER());
const signatureLength = uvarint64ToBuf(signatureBytes.length);
const signedTransactionBytes = Buffer.concat([
transactionBytes.slice(0, -1),
signatureLength,
signatureBytes
])
return signedTransactionBytes.toString('hex');
}
example transaction hex
01efa5060f5fdae5ed9d90e5f076b2c328a64e347d0c87e8e3317daec5a44fe7c8000102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322bab0405270000167b22426f6479223a2248656c6c6f20576f726c64227de807d461f4df9efad8a0f3f716002102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322b0000
example signed transaction hex returned from the javascript function
01efa5060f5fdae5ed9d90e5f076b2c328a64e347d0c87e8e3317daec5a44fe7c8000102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322bab0405270000167b22426f6479223a2248656c6c6f20576f726c64227de807d461f4df9efad8a0f3f716002102bd53e48625f49e60ff6b7a934e3871b54cc2a93a8737352e8320549e42e2322b00473045022100c36e2b80f2160304cf640b1296244e7a3873aacf2831098bca3727ad06f4c270022007d3697ceef266a05ad70219d92fbd570f6ec7a5731aaf02718213067d42d1cf
If you notice the signed hex is TransactionHex + 47 (length of signature) + 473045022100c36e2b80f2160304cf640b1296244e7a3873aacf2831098bca3727ad06f4c270022007d3697ceef266a05ad70219d92fbd570f6ec7a5731aaf02718213067d42d1cf (actual signature)
I am trying to use C# Bouncy Castle library in Unity3d to generate the signature part but no success.
This is the C# code (source)
public string GetSignature(string privateKey, string message)
{
var curve = SecNamedCurves.GetByName("secp256k1");
var domain = new ECDomainParameters(curve.Curve, curve.G, curve.N, curve.H);
var keyParameters = new ECPrivateKeyParameters(new BigInteger(privateKey, 16), domain);
var signer = new ECDsaSigner(new HMacDsaKCalculator(new Sha256Digest()));
signer.Init(true, keyParameters);
var signature = signer.GenerateSignature(Encoding.UTF8.GetBytes(message));
var r = signature[0];
var s = signature[1];
var otherS = curve.Curve.Order.Subtract(s);
if (s.CompareTo(otherS) == 1)
{
s = otherS;
}
var derSignature = new DerSequence
(
new DerInteger(new BigInteger(1, r.ToByteArray())),
new DerInteger(new BigInteger(1, s.ToByteArray()))
)
.GetDerEncoded();
return Convert(derSignature);
}
public string Convert(byte[] input)
{
return string.Concat(input.Select(x => x.ToString("x2")));
}
public byte[] Convert(string input)
{
if (input.StartsWith("0x")) input = input.Remove(0, 2);
return Enumerable.Range(0, input.Length / 2).Select(x => System.Convert.ToByte(input.Substring(x * 2, 2), 16)).ToArray();
}
This does generate a signature but it is not identical to the one I mentioned above.
Signature generated from GetSignature
3044022018a06b1f2b8a1e2f5ea2a78b0d6d98ec483b9fa4345821cfef892be6c825ff4702207958160e533c801dff5e50600206e1cd938d6df74ebfa4b0347a95de67dda986
P.S. Here is the python equivalent of signing transactions for reference.

sha256.x2() in the NodeJS code hashes twice, while ECDsaSigner in the C# code does not hash at all. Therefore, in the C# code, GetSignature() must explicitly hash twice:
using Org.BouncyCastle.Crypto.Digests;
...
var messageBytes = Convert(message);
var hash = GetHash(GetHash(messageBytes));
var signature = signer.GenerateSignature(hash);
...
with
private static byte[] GetHash(byte[] data)
{
var digest = new Sha256Digest();
var hash = new byte[digest.GetDigestSize()];
digest.BlockUpdate(data, 0, data.Length);
digest.DoFinal(hash, 0);
return hash;
}
Since both codes use the deterministic ECDSA algorithm according to RFC6979, the hashes for the same input data are identical and can be compared.
The overall result is the concatenation of txnHex without the last byte, the hex encoded length of the signature and the signature in ASN.1/DER format; a possible implementation is:
var txnHex = "...";
var seed = "...";
string signature = GetSignature(seed, txnHex);
string signedTransactionBytes = txnHex.Substring(0, txnHex.Length - 2) + (signature.Length / 2).ToString("x") + signature;
Note that the uvarint64ToBuf() implementation is actually more complex, but can be simplified for the signature lengths used here.

ECDSA get public key in C#

I can't figure this out it should be super simple.
I have both the C# and BouncyCastle (also C#) crypto libraries.
I just need to give a byte array as private key, specify the curve used and get the public key.
My curve is SEC-P-256-K1/secp256k1, but really if you can just help me navigate the sea of options and classes I don't need or care about I can set that myself.

Martin's answer seems fine, but it might be done easier:
public Tuple<byte[],byte[]> GetPublicKey(byte[] privateKey)
{
BigInteger privKeyInt = new BigInteger(+1, privateKey);
var parameters = SecNamedCurves.GetByName("secp256k1");
ECPoint qa = parameters.G.Multiply(privKeyInt);
byte[] pubKeyX = qa.X.ToBigInteger().ToByteArrayUnsigned();
byte[] pubKeyY = qa.Y.ToBigInteger().ToByteArrayUnsigned();
return Tuple.Create(pubKeyX, pubKeyY);
}

This is the solution. I was confused by the Curve constructors taking a parameter 'q' which was actually supposed to be 'p' (the prime modulus of the field).
I also don't understand why I have to do so much myself such as the point multiplication to get public key. How will others who have not read EC math know to do that?
Why is there no "GetPubKey" method!?!
Oh well I hope this helps someone. User friendly is not what BouncyCastle is about I guess.
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Crypto.Parameters;
using System.Text.RegularExpressions;
public static Tuple<byte[], byte[]> GetSecp256k1PublicKey(byte[] privateKey)
{
//Secp256k1 curve variables - https://en.bitcoin.it/wiki/Secp256k1
var privKeyInt = new BigInteger(+1, privateKey);
var a = new BigInteger("0");
var b = new BigInteger("7");
var GX = new BigInteger(+1, HexStringToByteArray("79BE667E F9DCBBAC 55A06295 CE870B07 029BFCDB 2DCE28D9 59F2815B 16F81798"));
var GY = new BigInteger(+1, HexStringToByteArray("483ADA77 26A3C465 5DA4FBFC 0E1108A8 FD17B448 A6855419 9C47D08F FB10D4B8"));
var n = new BigInteger(+1, HexStringToByteArray("FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE BAAEDCE6 AF48A03B BFD25E8C D0364141"));
var h = new BigInteger("1");
var p = new BigInteger(+1, HexStringToByteArray("FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFF FFFFFFFE FFFFFC2F"));
var q = h.Multiply(n).Mod(p); //Is this right???
//- http://en.wikipedia.org/wiki/Elliptic_curve_cryptography
ECCurve curve = new Org.BouncyCastle.Math.EC.FpCurve(p, a, b);
ECPoint G = new Org.BouncyCastle.Math.EC.FpPoint(curve, new FpFieldElement(p, GX), new FpFieldElement(p, GY));
var Qa = G.Multiply(privKeyInt);
byte[] PubKeyX = Qa.X.ToBigInteger().ToByteArrayUnsigned();
byte[] PubKeyY = Qa.Y.ToBigInteger().ToByteArrayUnsigned();
return Tuple.Create<byte[], byte[]>(PubKeyX, PubKeyY);
}
public static byte[] HexStringToByteArray(string hex)
{
if(String.IsNullOrWhiteSpace(hex))
return new byte[0];
hex = Regex.Replace(hex, "[\\s-\\{}]", "");
if (hex.Length % 2 == 1)
throw new Exception("The binary key cannot have an odd number of digits.");
if (!Regex.IsMatch(hex, "(^|\\A)[0-9A-Fa-f]*(\\Z|$)"))
throw new Exception("Not hex.");
byte[] arr = new byte[hex.Length >> 1];
hex = hex.ToUpper();
for (int i = 0; i < hex.Length >> 1; ++i)
{
arr[i] = (byte)((GetHexVal(hex[i << 1]) << 4) + (GetHexVal(hex[(i << 1) + 1])));
}
return arr;
}

Using Vasiliy's answer I was struggling to get the same results as this tutorial but finally got the correct results after changing his code by adding .Normalize():
public Tuple<byte[],byte[]> GetPublicKey(byte[] privateKey){
BigInteger privKeyInt = new BigInteger(+1, privateKey);
var parameters = SecNamedCurves.GetByName("secp256k1");
ECPoint qa = parameters.G.Multiply(privKeyInt).Normalize();
byte[] pubKeyX = qa.XCoord.ToBigInteger().ToByteArrayUnsigned();
byte[] pubKeyY = qa.YCoord.ToBigInteger().ToByteArrayUnsigned();
return Tuple.Create(pubKeyX, pubKeyY);
}
I'd add this as a comment but alas not enough reputation.

Trying to reproduce PHP's pack("H*") function in C#

this is my code in C# :
public static String MD5Encrypt(String str, Boolean raw_output=false)
{
// Use input string to calculate MD5 hash
String output;
MD5 md5 = System.Security.Cryptography.MD5.Create();
byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(str);
byte[] hashBytes = md5.ComputeHash(inputBytes);
// Convert the byte array to hexadecimal string
StringBuilder sb = new StringBuilder();
for (int i = 0; i < hashBytes.Length; i++)
{
sb.Append(hashBytes[i].ToString("x2"));
}
output = sb.ToString();
if (raw_output)
{
output = pack(output);
}
return output;
}
public static String pack(String S)
{
string MultiByte = "";
for (int i = 0; i <= S.Length - 1; i += 2)
{
MultiByte += Convert.ToChar(HexToDec(S.Substring(i, 2)));
}
return MultiByte;
}
private static int HexToDec(String hex)
{
//Int32.Parse(hexString, System.Globalization.NumberStyles.HexNumber);
return Convert.ToInt32(hex, 16);
}
To reproduce what is done in php by this way :
md5($str, true);
OR
pack('H*', md5( $str ));
I tried many things but can't get the same on the two sides in some cases of word.
For example, Trying this test on the string "8tv7er5j"
PHP Side :
9c36ad446f83ca38619e12d9e1b3c39e <= md5("8tv7er5j");
œ6­DoƒÊ8ažÙá³Ãž <= md5("8tv7er5j", true) or pack("H*", md5("8tv7er5j"))
C# Side :
9c36ad446f83ca38619e12d9e1b3c39e <= MD5Encrypt("8tv7er5j")
6­DoÊ8aÙá³Ã <= MD5Encrypt("8tv7er5j", true) or pack( MD5Encrypt("8tv7er5j") )
Why ? Encoding problem ?
EDIT 1 :
I have the good result, but bad encoded with this this function for pack() :
if ((hex.Length % 2) == 1) hex += '0';
byte[] bytes = new byte[hex.Length / 2];
for (int i = 0; i < hex.Length; i += 2)
{
bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
}
return bytes;
So, System.Text.Encoding.UTF8.GetString(bytes) give me :
�6�Do��8a���Þ
And System.Text.Encoding.ASCII.GetString(bytes)
?6?Do??8a??????
...

I encountered same scenario where I am in need of php's pack-unpack-md5 functions in C#. Most important was that I need to match out of all these 3 functions with php.
I created my own functions and then validated(verified) my output with functions at onlinephpfunctions.com. The output was same when I parsed with DefaultEncoding. FYI, I checked my application's encoding(Encoding.Default.ToString()) and it was System.Text.SBCSCodePageEncoding
Pack
private static string pack(string input)
{
//only for H32 & H*
return Encoding.Default.GetString(FromHex(input));
}
public static byte[] FromHex(string hex)
{
hex = hex.Replace("-", "");
byte[] raw = new byte[hex.Length / 2];
for (int i = 0; i < raw.Length; i++)
{
raw[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
}
return raw;
}
MD5
private static string md5(string input)
{
byte[] asciiBytes = Encoding.Default.GetBytes(input);
byte[] hashedBytes = MD5CryptoServiceProvider.Create().ComputeHash(asciiBytes);
string hashedString = BitConverter.ToString(hashedBytes).Replace("-", "").ToLower();
return hashedString;
}
Unpack
private static string unpack(string p1, string input)
{
StringBuilder output = new StringBuilder();
for (int i = 0; i < input.Length; i++)
{
string a = Convert.ToInt32(input[i]).ToString("X");
output.Append(a);
}
return output.ToString();
}
PS: User can enhance these functions with other formats

I guess that PHP defaults to Latin1 so the code should look like :
public static String PhpMd5Raw(string str)
{
var md5 = System.Security.Cryptography.MD5.Create();
var inputBytes = System.Text.Encoding.ASCII.GetBytes(str);
var hashBytes = md5.ComputeHash(inputBytes);
var latin1Encoding = System.Text.Encoding.GetEncoding("ISO-8859-1");
return latin1Encoding.GetString(hashBytes);
}

If you are going to feed the result as a key for HMAC-SHA1 hashing keep it as bytes[] and initialize the HMACSHA1 with the return value of this function: DO NOT convert it to a string and back to bytes, I have spent hours because of this mistake.
public static byte[] PackH(string hex)
{
if ((hex.Length % 2) == 1) hex += '0';
byte[] bytes = new byte[hex.Length / 2];
for (int i = 0; i < hex.Length; i += 2)
{
bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
}
return bytes;
}

I know this is an old question. I am posting my answer for anyone who might reach this page searching for it.
The following code is the full conversion of the pearl function pack("H*") to c#.
public static String Pack(String input)
{
input = input.Replace("-", " ");
byte[] hashBytes = new byte[input.Length / 2];
for (int i = 0; i < hashBytes.Length; i++)
{
hashBytes[i] = Convert.ToByte(input.Substring(i * 2, 2), 16);
}
return Encoding.UTF7.GetString(hashBytes); // for perl/php
}

I'm sorry. I didn't go with the questions completely. But if php code is as below,
$testpack = pack("H*" , "you value");
and if can't read the $testpack values(due to some non support format), then first do base64_encode as below and echo it.
echo base64_encode($testpack);
Then use Risky Pathak answer. For complete this answer I'll post his answer with some small modification like base 64 encoding etc.
var hex = "you value";
hex = hex.Replace("-", "");
byte[] raw = new byte[hex.Length / 2];
for (int i = 0; i < raw.Length; i++)
{
raw[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
}
var res = Convert.ToBase64String(raw);
Console.WriteLine(res);
Now if you compare both of values, those should be similar.
And all credit should go to the Risky Pathak answer.

The same in c# can be reached with Hex.Decode() method.
And bin2hex() in php is Hex.Encode().

From binary to UTF-16 text and vice versa

I would like to convert a hexedicimal binary to UTF-16
just like this converter in this website
http://sms.24cro.com/op_1_4_en.htm
note: I am not reading the binary from a file, it is coming as query-string to my website
Example input:
06270646062700200627062d06280640064006400640064006400640064006400640064006400640064006400643

There are a few steps here:
converting a hexadecimal string into a byte[]
converting a byte[] to a string
The second of these is trivial, for example:
byte[] blob = ...
string s = Encoding.Unicode.GetString(blob);
So how about the first? Each pair will be one byte, so:
byte[] blob = new byte[input.Length / 2];
For each pair, we need to convert a byte:
for(int i = 0; i < blob.Length ; i++) {
string pair = input.Substring(2 * i, 2);
blob[i] = Convert.ToByte(pair, 16); // from hex to byte
}
So putting that all together:
byte[] blob = new byte[input.Length / 2];
for(int i = 0; i < blob.Length ; i++) {
string pair = input.Substring(2 * i, 2);
blob[i] = Convert.ToByte(pair, 16); // from hex to byte
}
string s = Encoding.Unicode.GetString(blob);

Please find the code for converting hexa to Arabic.
byte[] blob = new byte[text1.Text.Length / 2];
for (int i = 0; i < blob.Length; i++)
{
string pair = text1.Text.Substring(2 * i, 2);
blob[i] = Convert.ToByte(pair,16); // from hex to byte
}
string s;//
s = Encoding.BigEndianUnicode.GetString(blob);
Label3.Text = s;

Binary to Text Translation C# [duplicate]

Hi i was able to convert a ASCII string to binary using a binarywriter .. as 10101011 . im required back to convert Binary ---> ASCII string .. any idea how to do it ?

This should do the trick... or at least get you started...
public Byte[] GetBytesFromBinaryString(String binary)
{
var list = new List<Byte>();
for (int i = 0; i < binary.Length; i += 8)
{
String t = binary.Substring(i, 8);
list.Add(Convert.ToByte(t, 2));
}
return list.ToArray();
}
Once the binary string has been converted to a byte array, finish off with
Encoding.ASCII.GetString(data);
So...
var data = GetBytesFromBinaryString("010000010100001001000011");
var text = Encoding.ASCII.GetString(data);

If you have ASCII charters only you could use Encoding.ASCII.GetBytes and Encoding.ASCII.GetString.
var text = "Test";
var bytes = Encoding.ASCII.GetBytes(text);
var newText = Encoding.ASCII.GetString(bytes);

Here is complete code for your answer
FileStream iFile = new FileStream(#"c:\test\binary.dat",
FileMode.Open);
long lengthInBytes = iFile.Length;
BinaryReader bin = new BinaryReader(aFile);
byte[] byteArray = bin.ReadBytes((int)lengthInBytes);
System.Text.Encoding encEncoder = System.Text.ASCIIEncoding.ASCII;
string str = encEncoder.GetString(byteArray);

Take this as a simple example:
public void ByteToString()
{
Byte[] arrByte = { 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 };
string x = Convert.ToBase64String(arrByte);
}
This linked answer has interesting details about this kind of conversion:
binary file to string

Sometimes instead of using the built in tools it's better to use "custom" code.. try this function:
public string BinaryToString(string binary)
{
if (string.IsNullOrEmpty(binary))
throw new ArgumentNullException("binary");
if ((binary.Length % 8) != 0)
throw new ArgumentException("Binary string invalid (must divide by 8)", "binary");
StringBuilder builder = new StringBuilder();
for (int i = 0; i < binary.Length; i += 8)
{
string section = binary.Substring(i, 8);
int ascii = 0;
try
{
ascii = Convert.ToInt32(section, 2);
}
catch
{
throw new ArgumentException("Binary string contains invalid section: " + section, "binary");
}
builder.Append((char)ascii);
}
return builder.ToString();
}
Tested with 010000010100001001000011 it returned ABC using the "raw" ASCII values.