Develop Reference

Hex input to SHA256 hash

online hash code can be obtained from this site with SHA256.
https://emn178.github.io/online-tools/sha256.html
The hash code of 1 is "6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b"
but if we make the hash code input type of 1 hex, "4bf5122f344554c53bde2ebb8cd2b7e3d1600ad631c385a5d7cce23c7785459a" comes out.
I can do the first one in c# code, but I couldn't find a c# code that can do the second one. Could you help?
static string ComputeSha256Hash(string rawData)
{
// Create a SHA256
using (SHA256 sha256Hash = SHA256.Create())
{
// ComputeHash - returns byte array
byte[] bytes = sha256Hash.ComputeHash(Encoding.UTF8.GetBytes(rawData));
// Convert byte array to a string
StringBuilder builder = new StringBuilder();
for (int i = 0; i < bytes.Length; i++)
{
builder.Append(bytes[i].ToString("x2"));
}
return builder.ToString();
}
}

Please try this, the key is convert hex to bytes.
public static byte[] StringToByteArray(string hex)
{
int len = hex.Length;
//the stackoverflow answer assumes you have even length,
//so I insert a 0 if odd length.
if (len % 2 == 1)
{
hex = hex.Insert(0, "0");
}
return Enumerable.Range(0, len)
.Where(x => x % 2 == 0)
.Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
.ToArray();
}
static string ComputeSha256Hash(string rawData)
{
using (SHA256 sha256Hash = SHA256.Create())
{
byte[] bytes = sha256Hash.ComputeHash(StringToByteArray(rawData));
StringBuilder builder = new StringBuilder();
for (int i = 0; i < bytes.Length; i++)
{
builder.Append(bytes[i].ToString("x2"));
}
return builder.ToString();
}
}
static void Main(string[] args)
{
string hash = ComputeSha256Hash("1");
Console.WriteLine(hash);
Console.ReadKey();
}

C# encrypt code and c++ encrypt code is not matching

I'm implementing encrypt/decrypt code with c++/c#
I referred to this post and referred to answers.z`
But c++/c# encrypted code was not matched.
Here are my codes.
C++
// base64 encode part
static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static inline bool is_base64(BYTE c) {
return (isalnum(c) || (c == '+') || (c == '/'));
}
std::string base64_encode(BYTE const* buf, unsigned int bufLen) {
std::string ret;
int i = 0;
int j = 0;
BYTE char_array_3[3];
BYTE char_array_4[4];
while (bufLen--) {
char_array_3[i++] = *(buf++);
if (i == 3) {
char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
char_array_4[3] = char_array_3[2] & 0x3f;
for (i = 0; (i < 4); i++)
ret += base64_chars[char_array_4[i]];
i = 0;
}
}
if (i)
{
for (j = i; j < 3; j++)
char_array_3[j] = '\0';
char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
char_array_4[3] = char_array_3[2] & 0x3f;
for (j = 0; (j < i + 1); j++)
ret += base64_chars[char_array_4[j]];
while ((i++ < 3))
ret += '=';
}
return ret;
}
//start encrypt
std::string key = "01286567891233460123456789a12345";
std::string iv = "0123456789123456";
std::string encrypt(const std::string& str_in)
{
std::string str_out;
std::string str_out2;
byte* keybyte = (byte*)key.c_str();
CryptoPP::AES::Encryption aesEncryption((byte*)key.c_str(), CryptoPP::AES::MAX_KEYLENGTH);
CryptoPP::CBC_Mode_ExternalCipher::Encryption cbcEncryption(aesEncryption, (byte*)iv.c_str());
StreamTransformationFilter stfEncryptor(cbcEncryption, new CryptoPP::StringSink(str_out));
stfEncryptor.Put(reinterpret_cast<const unsigned char*>(str_in.c_str()), str_in.length() + 1);
stfEncryptor.MessageEnd();
str_out2 = base64_encode(reinterpret_cast<const unsigned char*>(str_out.c_str()), strlen(str_out.c_str()));
return str_out2;
}
std::string decrypt(const std::string& cipher_text)
{
std::string str_out;
//need to insert code of decrypt base64
CryptoPP::AES::Decryption aesDecryption((byte*)key.c_str(), CryptoPP::AES::MAX_KEYLENGTH);
CryptoPP::CBC_Mode_ExternalCipher::Decryption cbcDecryption(aesDecryption, (byte*)iv.c_str());
CryptoPP::StreamTransformationFilter stfDecryptor(cbcDecryption, new CryptoPP::StringSink(str_out));
stfDecryptor.Put(reinterpret_cast<const unsigned char*>(cipher_text.c_str()), cipher_text.size());
stfDecryptor.MessageEnd();
return str_out;
}
c#
public string Encrypt(string testCode)
{
string clearText = testCode;
byte[] clearBytes = Encoding.Default.GetBytes(clearText);
using (Aes encryptor = Aes.Create("AES"))
{
//encryptor.BlockSize = 128;
encryptor.Padding = PaddingMode.Zeros;
encryptor.KeySize = 128;
encryptor.Mode = CipherMode.CBC;
encryptor.Key = Encoding.Default.GetBytes("01286567891233460123456789a12345");
encryptor.IV = Encoding.Default.GetBytes("0123456789123456");
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(clearBytes, 0, clearBytes.Length);
cs.Close();
}
byte[] bt = ms.ToArray();
clearText = Convert.ToBase64String(bt); //clearText = Encoding.Default.GetString(bt);
}
}
return clearText; //Return the encrypted command
}
public string Decrypt(string cipherText)
{
byte[] clearBytes = Convert.FromBase64String(cipherText);
using (Aes decryptor = Aes.Create("AES"))
{
// decryptor.BlockSize = 128;
decryptor.Padding = PaddingMode.Zeros;
decryptor.KeySize = 128;
decryptor.Mode = CipherMode.CBC;
decryptor.Key = Encoding.Default.GetBytes("01286567891233460123456789a12345");
decryptor.IV = Encoding.Default.GetBytes("0123456789123456");
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, decryptor.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(clearBytes, 0, clearBytes.Length);
cs.Close();
}
byte[] bt = ms.ToArray();
cipherText = Encoding.Default.GetString(bt);
}
}
return cipherText; //Return the decrypted text
}
c++ result
encrypted code : ks8zzu20w6zURkuZMgbx8g==
decrypted code : test
c# result
encrypted code : nsWRYBylyjVaJ5Yckk+SRw==
decrypted code : test
I tested with test word both of C++/C# however encrypted code was not matched.
Also, I tested after remove base64 encode code but pure encrypted code was not matched as well.
Could anyone please share your knowledge?
EDIT1
I tried to copy encrypted code by c++ and pasted to c# decrypt code like below
string testcode = "ks8zzu20w6zURkuZMgbx8g=="
Decrypt(testcode)
//result - test↗↗↗↗↗
As you can see, the results look very similar, but there is something weird.
↗ This symbol is added after the word test.
I could not found out why result like this. Is there something I missed?
Solved
std::string encrypt(const std::string& str_in)
{
std::string str_out;
std::string str_out2;
byte* keybyte = (byte*)key.c_str();
CryptoPP::AES::Encryption aesEncryption((byte*)key.c_str(), CryptoPP::AES::MAX_KEYLENGTH);
CryptoPP::CBC_Mode_ExternalCipher::Encryption cbcEncryption(aesEncryption, (byte*)iv.c_str());
StreamTransformationFilter stfEncryptor(cbcEncryption, new CryptoPP::StringSink(str_out));
// 'str_in.length() + 1' in the line below makes the encryption code different from c# code.
/*stfEncryptor.Put(reinterpret_cast<const unsigned char*>(str_in.c_str()), str_in.length() + 1);*/
stfEncryptor.Put(reinterpret_cast<const unsigned char*>(str_in.c_str()), str_in.length());
stfEncryptor.MessageEnd();
str_out2 = cryptobase64_encode(str_out);
return str_out2;
}
As I commented, str_in.length() + 1 makes the encrypted code different from C# code.
And I changed C# padding options from Zeros to PKCS7 for matching c++ encrypted code.
But I don't know why I need to set this option. I think I need to study this.
Anyway, It works well. Special thanks to #jdweng.

Find bytes from an offset

So I have this:
public static long FindPosition(Stream stream, byte[] byteSequence)
{
if (byteSequence.Length > stream.Length)
return -1;
byte[] buffer = new byte[byteSequence.Length];
using (BufferedStream bufStream = new BufferedStream(stream, byteSequence.Length))
{
int i;
while ((i = bufStream.Read(buffer, 0, byteSequence.Length)) == byteSequence.Length)
{
if (byteSequence.SequenceEqual(buffer))
return bufStream.Position - byteSequence.Length;
else
bufStream.Position -= byteSequence.Length - PadLeftSequence(buffer, byteSequence);
}
}
return -1;
}
private static int PadLeftSequence(byte[] bytes, byte[] seqBytes)
{
int i = 1;
while (i < bytes.Length)
{
int n = bytes.Length - i;
byte[] aux1 = new byte[n];
byte[] aux2 = new byte[n];
Array.Copy(bytes, i, aux1, 0, n);
Array.Copy(seqBytes, aux2, n);
if (aux1.SequenceEqual(aux2))
return i;
i++;
}
return i;
}
Which works perfectly to get an offset that has a specific set of bytes, but now I want to do the inverse, find a set of bytes from a specific offset.
How can I do that?

Try this example:
long offset = 100L; // Offset
int bytesCount = 20; // Number of bytes to read
byte[] buffer = new byte[bytesCount];
stream.Seek( offset, SeekOrigin.Begin ); // Set offset from Begin of a stream
stream.Read( buffer, 0, bytesCount ); // Read bytesCount from previous set offset
More detail about Seek and Read

How to convert from decimal to binary invert it with ~ and convert back to decimal

Not sure if I am in the right direction.
I can't find info about tilde.
int n = 5;
int m = ~n;
string numAsString = Convert.ToString(~n, 2);
char[] NumAsChar = numAsString.ToCharArray();
long l = Convert.ToInt64(numAsString, 2);
Console.WriteLine(numAsString);
Console.WriteLine(l);

You're probably looking for a simple answer.
int n = 5;
byte[] nbytes = BitConverter.GetBytes(n);
for(int i = 0 ; i < nbytes.Length; i++)
nbytes[i] = ~nbytes[i];
n = BitConverter.ToInt32(nbytes, 0);
edit: you actually can't do ~ on a byte[]. You can either do
for(int i = 0 ; i < nbytes.Length; i++)
nbytes[i] = ~nbytes[i];
or just not use a byte array at all.
For clarity's sake, do note that you can just do
n = ~n;
and skip doing any of the separation. But you specifically asked for the byte conversion.

Use these 2 methods
static byte[] GetBytes(string str)
{
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
static string GetString(byte[] bytes)
{
char[] chars = new char[bytes.Length / sizeof(char)];
System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
return new string(chars);
}
And then use them like this
byte[] bytes = GetTheBytes(str);
byte[] reversed = bytes.Reverse().ToArray();
var revStr = GetString(reversed)

I did it like this.Any suggestions on making it simpler.
int n = 100;
//Convert decimal to binary
string numAsString = Convert.ToString(n, 2);
char[] NumAsChar = numAsString.ToCharArray();
Console.WriteLine(numAsString);
//Invert bits
for (int i = 0; i < numAsString.Length; i++)
{
if (NumAsChar[i] == '0')
{
NumAsChar[i] = '1';
}
else
{
NumAsChar[i] = '0';
}
}
string NewNumAsString = new string(NumAsChar);
//Convert inverted binary num to decimal
long l = Convert.ToInt64(NewNumAsString, 2);
Console.WriteLine(NewNumAsString);
Console.WriteLine(l);

Encode decoded string with Base64String

I am learning how to encode and decode string. This is a method to decode chiper text to plain text I found around the web.
public static string Decode(string chiperText)
{
byte[] numArray = Convert.FromBase64String(chiperText);
byte[] numArray1 = new byte[(int)numArray.Length - 1];
byte num = (byte)(numArray[0] ^ 188);
for (int i = 1; i < (int)numArray.Length; i++)
{
numArray1[i - 1] = (byte)(numArray[i] ^ 188 ^ num);
}
return Encoding.ASCII.GetString(numArray1);
}
My problem is I have no idea how to encode to original state. I try this method and it doesn't work.
public static string Encode(string plainText)
{
byte[] bytes = Encoding.ASCII.GetBytes(plainText);
byte[] results = new byte[(int)bytes.Length - 1];
byte num = (byte)(bytes[0] ^ 188);
for (int i = 1; i < bytes.Length; i++)
{
results[i - 1] = (byte)(bytes[i] ^ 188 ^ num);
}
return Convert.ToBase64String(results);
}

Although I agree entirely with SLaks comment that the above does not constitute any kind of crypto that you should use, the following procedure will produce the "encrypted" data that you are looking to decrypt:
public static string Encode(string plainText)
{
byte[] numArray = System.Text.Encoding.Default.GetBytes(plainText);
byte[] numArray1 = new byte[(int)numArray.Length + 1];
// Generate a random byte as the seed used
(new Random()).NextBytes(numArray1);
byte num = (byte)(numArray1[0] ^ 188);
numArray1[0] = numArray1[0];
for (int i = 0; i < (int)numArray.Length; i++)
{
numArray1[i + 1] = (byte)(num ^ 188 ^ numArray[i]);
}
return Convert.ToBase64String(numArray1);
}
Please do not, for a single second, consider using this as a method for 'encrypting' sensitive data.