public static byte[] SymmetricEnryption(byte[] clearData, SymmetricKeys keys)
{
//0. declare the algorithm to use
Rijndael myAlg = Rijndael.Create();
//1. first we generate the secret key and iv
//var keys = GenerateKeys();
//2. load the data into a memoryStream
MemoryStream msIn = new MemoryStream(clearData);
msIn.Position = 0; //Making sure that the pointer of the byte to read next is at the beginning so we encrypt everything
//3. declare where to store the encrypted data
MemoryStream msOut = new MemoryStream();
//4. declaring a Stream which handles data encryption
CryptoStream cs = new CryptoStream(msOut, myAlg.CreateEncryptor(keys.SecretKey, keys.Iv), CryptoStreamMode.Write);
//5. we start the encrypting engine
msIn.CopyTo(cs);
//6. make sure that the data is all written (flushed) into msOut
cs.FlushFinalBlock();
//7
cs.Close();
//8
return(msOut.ToArray());
}
public static MemoryStream HybridDecrypt(MemoryStream encFile, string privateKey)
{
encFile.Position = 0;
//1) Read enc key
byte[] retrievedEncKey = new byte[128];
encFile.Read(retrievedEncKey, 0, 128);
//2) Read enc iv
byte[] retrievedEncIv = new byte[128];
encFile.Read(retrievedEncIv, 0, 128);
//3) Decrypt using the privatekey (asymmetric) the 1 and 2
byte[] decKey = AsymmetricDecrypt(retrievedEncKey, privateKey);
byte[] decIv = AsymmetricDecrypt(retrievedEncIv, privateKey);
SymmetricKeys keys = new SymmetricKeys();
keys.SecretKey = decKey;
keys.Iv = decIv;
//4) Read the rest of the file (which is the actual file content)
MemoryStream actualencryptedfilecontent = new MemoryStream();
encFile.CopyTo(actualencryptedfilecontent);
//5 Symmetrically dec what you read in no 4 using what you dec in step no 3
byte[] bytes = actualencryptedfilecontent.ToArray();
byte[] decFile = SymmetricDecrypt(bytes, keys);
MemoryStream actualFile = new MemoryStream(decFile);
return(actualFile);
}
public static SymmetricKeys GenerateKeys()
{
Rijndael myAlg = Rijndael.Create();
Rfc2898DeriveBytes myGenerator = new Rfc2898DeriveBytes(password, salt);
SymmetricKeys keys = new SymmetricKeys()
{
SecretKey = myGenerator.GetBytes(myAlg.KeySize / 8),
Iv = myGenerator.GetBytes(myAlg.BlockSize / 8)
};
return(keys);
}
public static SymmetricKeys GenerateKeys()
{
// Password + Salt >>>>> Algorithm >>> Secret Key + IV (which is the input needed by the encryption algorithm)
Rijndael myAlg = Rijndael.Create();
Rfc2898DeriveBytes myGenerator = new Rfc2898DeriveBytes(password, salt);
SymmetricKeys keys = new SymmetricKeys()
{ //1 byte = 8 bits
SecretKey = myGenerator.GetBytes(myAlg.KeySize / 8),
Iv = myGenerator.GetBytes(myAlg.BlockSize / 8)
};
return(keys);
}
public static MemoryStream HybridEncrypt(MemoryStream clearFile, string publicKey)
{
//1. Generate the symmetric keys
Rijndael myAlg = Rijndael.Create();
myAlg.GenerateKey();
myAlg.GenerateIV();
var key = myAlg.Key;
var iv = myAlg.IV;
//2. Encrypting the clearFile using Symmetric Encryption
SymmetricKeys keys = new SymmetricKeys();
keys.SecretKey = key;
keys.Iv = iv;
//3. Asymmetrically encrypt using the public key, the sym key and iv above
//string keyS = Convert.ToBase64String(key);
byte[] encryptedKey = AsymmetricEnrypt(key, publicKey);
//4. Store the above encrypted data n one file
byte[] encryptedIv = AsymmetricEnrypt(iv, publicKey);
MemoryStream msOut = new MemoryStream();
msOut.Write(encryptedKey, 0, encryptedKey.Length);
msOut.Write(encryptedIv, 0, encryptedIv.Length);
byte[] bytes = clearFile.ToArray();
byte[] encryptedBytes = SymmetricEnryption(bytes, keys);
MemoryStream encryptedfileContent = new MemoryStream(encryptedBytes);
encryptedfileContent.Position = 0;
encryptedfileContent.CopyTo(msOut);
return(msOut);
}
