I've made a small application to encrypt and decrypt some text. All is fine as long as I use the byte array straight from the encryption. But as soon as I make a copy of the array to mimic the process of sending the encrypted text as a file the decryption will not run.
Why am I unable the run the decryption using a copied array?
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Security.Cryptography;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Runtime.InteropServices;
using System.IO;
namespace EncryptDecryptApplication
{
class Program
{
static void Main(string[] args)
{
//Text to encrypt
string plaintext = "Text to encrypt and decrypt!";
// Password
const string password = "password";
// Constants used in cryptography functions
const string MS_ENH_RSA_AES_PROV = "Microsoft Enhanced RSA and AES Cryptographic Provider"; //Name of provider. Same as "Microsoft AES Cryptographic Provider".
const byte PROV_RSA_AES = 24; //Type of provider
const string KeyContainer = null; //Name of the key container to be used, if NULL then a default key container name is used. Must be a null-terminated string.
const uint ALG_CLASS_HASH = (4 << 13); //32768 = 4*2^13; //Samma tror jag för alla hashalgoritmer
const uint ALG_TYPE_ANY = (0); //Samma tror jag för alla hashalgoritmer
const uint ALG_SID_SHA_256 = 12; //ALG_SID_MD5 = 3, ALG_SID_SHA = 4, ALG_SID_SHA_256 = 12, ALG_SID_SHA_384 = 13, ALG_SID_SHA_512 = 14
const uint CALG_SHA_256 = (ALG_CLASS_HASH | ALG_TYPE_ANY | ALG_SID_SHA_256);
const int ALG_CLASS_DATA_ENCRYPT = 24576;
const int ALG_TYPE_BLOCK = 1536; //used in all types of AES, and in RC2
const int ALG_SID_AES_256 = 16; //ALG_SID_AES_128 = 14, ALG_SID_AES_192 = 15, ALG_SID_AES_256 = 16
const int CALG_AES_256 = (ALG_CLASS_DATA_ENCRYPT | ALG_TYPE_BLOCK | ALG_SID_AES_256);
const int ENCRYPT_ALGORITHM = CALG_AES_256;
// Obtain handle to Cryptographic Service Provider (CSP)
string ProviderCSP = MS_ENH_RSA_AES_PROV + null; //name of the CSP to be used. Must be a null-terminated string.
IntPtr CSPhandle = new IntPtr();
Crypt32.CryptAcquireContext(ref CSPhandle, KeyContainer, ProviderCSP, PROV_RSA_AES, 0);
//Create hash object
IntPtr handleHashObj = new IntPtr();
Crypt32.CryptCreateHash(CSPhandle, CALG_SHA_256, IntPtr.Zero, 0, ref handleHashObj);
//Hash password
byte[] pwByteArray = Encoding.Unicode.GetBytes(password);
uint pwByteAmt = (uint)ASCIIEncoding.Unicode.GetByteCount(password);
Crypt32.CryptHashData(handleHashObj, pwByteArray, pwByteAmt, 0);
//Dervie session key from the hashed password
IntPtr handleSessionKey = new IntPtr();
Crypt32.CryptDeriveKey(CSPhandle, ENCRYPT_ALGORITHM, handleHashObj, 0, ref handleSessionKey);
//CryptEncrypt iteration no 1 - Obtain buffer size (output ByteAmt_Itr1)
byte[] byteArray = new byte[plaintext.Length * sizeof(char)];
System.Buffer.BlockCopy(plaintext.ToCharArray(), 0, byteArray, 0, byteArray.Length);
uint byteAmt_Itr1 = (uint)byteArray.Length; //No of bytes, i.e. the size, of the plaintext.
uint bufferSize_Itr1 = byteAmt_Itr1; //Set buffer size to input data size for now
Crypt32.CryptEncrypt(handleSessionKey, IntPtr.Zero, 1, 0, null, ref byteAmt_Itr1, 0);
//CryptEncrypt iteration no 2 - Encryption
uint byteAmt_Itr2 = (uint)byteArray.Length; //No of bytes, i.e. the size, of the plaintext.
uint bufferSize_Itr2 = byteAmt_Itr1; //Output from iteration no 1 - size of output data, i.e. correct buffer size
Crypt32.CryptEncrypt(handleSessionKey, IntPtr.Zero, 1, 0, byteArray, ref byteAmt_Itr2, bufferSize_Itr2);
Console.WriteLine("Encrypted: " + Encoding.Default.GetString(byteArray));
// Text encrypted as byteArray, try to decrypt it! //
//CryptDecrypt - with input from CryptEncrypt".
Console.WriteLine(Crypt32.CryptDecrypt(handleSessionKey, IntPtr.Zero, 1, 0, byteArray, ref byteAmt_Itr2));
//Convert decrypted byte array to string
char[] chars = new char[byteArray.Length / sizeof(char)];
System.Buffer.BlockCopy(byteArray, 0, chars, 0, byteArray.Length);
string decryptedText = new string(chars);
Console.WriteLine("Decrypted: " + decryptedText);
}
}
public class Crypt32
{
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptAcquireContext(
ref IntPtr hProv,
string pszContainer,
string pszProvider,
uint dwProvType,
uint dwFlags);
[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptCreateHash(
IntPtr hProv,
uint algId,
IntPtr hKey,
uint dwFlags,
ref IntPtr phHash);
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptHashData(
IntPtr hHash,
byte[] pbData,
uint dataLen,
uint flags);
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptDeriveKey(
IntPtr hProv,
int Algid,
IntPtr hBaseData,
int flags,
ref IntPtr phKey);
[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptEncrypt(
IntPtr hKey,
IntPtr hHash,
int Final,
uint dwFlags,
byte[] pbData,
ref uint pdwDataLen,
uint dwBufLen);
[DllImport("advapi32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool CryptDecrypt(
IntPtr hKey,
IntPtr hHash,
int Final,
uint dwFlags,
byte[] pbData,
ref uint pdwDataLen);
}
}
Output:
Encrypted:
B'♦tt'sô?*ý¢┼àò⌂9Z▼?£'$'¥«çæOÆà[/ë?·UÛÙªÄ2?┼[É{&IâínaÇe
True
Decrypted: Text to encrypt and decrypt!
I've sorted out the other inputs to CryptDecrypt (have made another handleSessionKey and also another variable instead of byteAtm_Itr2), they are not the source of the problem. The problem seems to be with the byte array.
If I use this code (or Buffer.BlockCopy) to copy the array the decryption will fail:
byte[] byteArray2 = new byte[byteArray.Length];
byteArray.CopyTo(byteArray2, 0);
The arrays are the same but of course not the same object. Can't work out why this wouldn't work. If I run the code with the copied array this is the output:
Encrypted:
B'♦tt'sô?*ý¢┼àò⌂9Z▼?£'$'¥«çæOÆà[/ë?·UÛÙªÄ2?┼[É{&IâínaÇe
False
Decrypted: Text to encrypt and decr????
