private static void Encrypt(FileStream inputFile, FileStream outputFile, byte[] nonce, byte[] dataEncryptionKey, byte[] additionalData)
{
const int offset = 0;
byte[] plaintextChunk = new byte[Constants.FileChunkSize];
while (inputFile.Read(plaintextChunk, offset, plaintextChunk.Length) > 0)
{
byte[] ciphertextChunk = XChaCha20BLAKE2b.Encrypt(plaintextChunk, nonce, dataEncryptionKey, additionalData, TagLength.Medium);
nonce = Utilities.Increment(nonce);
additionalData = ChunkHandling.GetPreviousTag(ciphertextChunk);
outputFile.Write(ciphertextChunk, offset, ciphertextChunk.Length);
}
CryptographicOperations.ZeroMemory(dataEncryptionKey);
}
private static void Decrypt(FileStream inputFile, FileStream outputFile, byte[] nonce, byte[] dataEncryptionKey, byte[] additionalData, int lastChunkLength)
{
inputFile.Seek(Constants.FileHeadersLength, SeekOrigin.Begin);
const int offset = 0;
byte[] ciphertextChunk = new byte[Constants.TotalChunkLength];
while (inputFile.Read(ciphertextChunk, offset, ciphertextChunk.Length) > 0)
{
byte[] plaintextChunk = XChaCha20BLAKE2b.Decrypt(ciphertextChunk, nonce, dataEncryptionKey, additionalData, TagLength.Medium);
nonce = Utilities.Increment(nonce);
additionalData = ChunkHandling.GetPreviousTag(ciphertextChunk);
outputFile.Write(plaintextChunk, offset, plaintextChunk.Length);
}
outputFile.SetLength(outputFile.Length - Constants.FileChunkSize + lastChunkLength);
CryptographicOperations.ZeroMemory(dataEncryptionKey);
}
public static void Initialize(FileStream inputFile, string outputFilePath, byte[] ephemeralPublicKey, byte[] keyEncryptionKey)
{
var dataEncryptionKey = new byte[Constants.EncryptionKeyLength];
try
{
byte[] encryptedHeader = FileHeaders.ReadEncryptedHeader(inputFile);
byte[] nonce = FileHeaders.ReadNonce(inputFile);
byte[] header = DecryptFileHeader(inputFile, ephemeralPublicKey, encryptedHeader, nonce, keyEncryptionKey);
if (header == null)
{
throw new ArgumentException("Incorrect password/key or this file has been tampered with.");
}
int lastChunkLength = FileHeaders.GetLastChunkLength(header);
int fileNameLength = FileHeaders.GetFileNameLength(header);
dataEncryptionKey = FileHeaders.GetDataEncryptionKey(header);
CryptographicOperations.ZeroMemory(header);
using (var outputFile = new FileStream(outputFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read, Constants.FileStreamBufferSize, FileOptions.SequentialScan))
{
nonce = Utilities.Increment(nonce);
byte[] additionalData = ChunkHandling.GetPreviousTag(encryptedHeader);
Decrypt(inputFile, outputFile, nonce, dataEncryptionKey, additionalData, lastChunkLength);
}
string inputFilePath = inputFile.Name;
inputFile.Dispose();
Finalize(inputFilePath, outputFilePath, fileNameLength);
}
catch (Exception ex) when(ExceptionFilters.Cryptography(ex))
{
CryptographicOperations.ZeroMemory(dataEncryptionKey);
if (!(ex is ArgumentException))
{
FileHandling.DeleteFile(outputFilePath);
}
throw;
}
}
public static void Initialize(string inputFilePath, string outputFilePath, byte[] ephemeralPublicKey, byte[] salt, byte[] keyEncryptionKey)
{
byte[] dataEncryptionKey = Generate.DataEncryptionKey();
try
{
using (var inputFile = new FileStream(inputFilePath, FileMode.Open, FileAccess.Read, FileShare.Read, Constants.FileStreamBufferSize, FileOptions.SequentialScan))
using (var outputFile = new FileStream(outputFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read, Constants.FileStreamBufferSize, FileOptions.SequentialScan))
{
byte[] nonce = Generate.Nonce();
byte[] encryptedHeader = EncryptFileHeader(inputFilePath, ephemeralPublicKey, dataEncryptionKey, nonce, keyEncryptionKey);
FileHeaders.WriteHeaders(outputFile, ephemeralPublicKey, salt, nonce, encryptedHeader);
nonce = Utilities.Increment(nonce);
byte[] additionalData = ChunkHandling.GetPreviousTag(encryptedHeader);
Encrypt(inputFile, outputFile, nonce, dataEncryptionKey, additionalData);
}
Finalize(inputFilePath, outputFilePath);
}
catch (Exception ex) when(ExceptionFilters.Cryptography(ex))
{
FileHandling.DeleteFile(outputFilePath);
CryptographicOperations.ZeroMemory(dataEncryptionKey);
throw;
}
}
