public void PackingAndUnpackingResultsInOriginal()
{
CryptoHeader header = new CryptoHeader
{
PackageName = "MyAppName",
AlgorithmName = "Twofish",
KdfName = "PBKDF2",
Cost = "10",
Nonce = CommonMocksAndStubs.FilledByteArray(8, 66),
Salt = CommonMocksAndStubs.FilledByteArray(8, 77),
Compression = "gzip",
};
byte[] cipher = CommonMocksAndStubs.FilledByteArray(16, 88);
byte[] packedHeader = CryptoHeaderPacker.PackHeaderAndCypher(header, cipher);
CryptoHeaderPacker.UnpackHeaderAndCipher(packedHeader, "MyAppName", out CryptoHeader unpackedHeader, out byte[] unpackedCipher);
Assert.AreEqual(header.PackageName, unpackedHeader.PackageName);
Assert.AreEqual(header.AlgorithmName, unpackedHeader.AlgorithmName);
Assert.AreEqual(header.KdfName, unpackedHeader.KdfName);
Assert.AreEqual(header.Cost, unpackedHeader.Cost);
Assert.AreEqual(header.Nonce, unpackedHeader.Nonce);
Assert.AreEqual(header.Salt, unpackedHeader.Salt);
Assert.AreEqual(cipher, unpackedCipher);
Assert.AreEqual(header.Compression, unpackedHeader.Compression);
}
public void PackingAndUnpackingWorksWithKeyOnly()
{
// If the encryption is started with a key instead of a password, there are not all parametes set.
CryptoHeader header = new CryptoHeader
{
PackageName = "MyAppName",
AlgorithmName = "Twofish",
KdfName = null,
Cost = null,
Nonce = CommonMocksAndStubs.FilledByteArray(8, 66),
Salt = null,
Compression = "gzip",
};
byte[] cipher = CommonMocksAndStubs.FilledByteArray(16, 88);
byte[] packedHeader = CryptoHeaderPacker.PackHeaderAndCypher(header, cipher);
CryptoHeaderPacker.UnpackHeaderAndCipher(packedHeader, "MyAppName", out CryptoHeader unpackedHeader, out byte[] unpackedCipher);
Assert.AreEqual(header.PackageName, unpackedHeader.PackageName);
Assert.AreEqual(header.AlgorithmName, unpackedHeader.AlgorithmName);
Assert.AreEqual(header.KdfName, unpackedHeader.KdfName);
Assert.AreEqual(header.Cost, unpackedHeader.Cost);
Assert.AreEqual(header.Nonce, unpackedHeader.Nonce);
Assert.AreEqual(header.Salt, unpackedHeader.Salt);
Assert.AreEqual(cipher, unpackedCipher);
Assert.AreEqual(header.Compression, unpackedHeader.Compression);
}
public static CryptoHeader ReadHeader(Stream cipherTextStream, bool leaveOpen)
{
cipherTextStream.Position = 0;
var header = new CryptoHeader();
using (var br = new BinaryReader(cipherTextStream, Encoding.UTF8, leaveOpen))
{
header.PayloadLength = UnpackInt64(br);
header.Magic = UnpackBytes(br);
if (header.Magic.SequenceEqual(brPackMagic) == false)
{
throw new Exception("Unsupported magic.");
}
header.Signature = UnpackBytes(br);
header.EncryptionAlgorithm = UnpackString(br);
if (header.EncryptionAlgorithm != EncryptionType.Aes256CbcPkcs7)
{
throw new Exception("Unsupported encryption algorithm.");
}
header.CreatedBy = UnpackBytes(br);
header.Id = UnpackString(br);
header.KeyId = UnpackString(br);
header.Purpose = UnpackString(br);
header.MimeType = UnpackString(br);
header.Created = DateTimeOffset.FromUnixTimeMilliseconds(UnpackInt64(br));
header.Iv = UnpackBytes(br);
header.CipherMetadata = UnpackBytes(br);
}
return(header);
}
public static async Task <string> DecryptAndUncompressStreamAsync(byte[] key, Stream cipherTextStream, Stream tempUncompressStream, Stream plainTextStream)
{
if (key == null || key.Length != 32)
{
throw new ArgumentNullException("key");
}
string metadata = null;
cipherTextStream.Position = 0;
tempUncompressStream.Position = 0;
plainTextStream.Position = 0;
var header = new CryptoHeader();
long signaturePosition;
using (var br = new BinaryReader(cipherTextStream, Encoding.UTF8, true))
{
header.PayloadLength = UnpackInt64(br);
header.Magic = UnpackBytes(br);
if (header.Magic.SequenceEqual(brPackMagic) == false)
{
throw new Exception("Unsupported magic.");
}
signaturePosition = cipherTextStream.Position;
header.Signature = UnpackBytes(br);
header.EncryptionAlgorithm = UnpackString(br);
if (header.EncryptionAlgorithm != EncryptionType.Aes256CbcPkcs7)
{
throw new Exception("Unsupported encryption algorithm.");
}
header.CreatedBy = UnpackBytes(br);
header.Id = UnpackString(br);
header.KeyId = UnpackString(br);
header.Purpose = UnpackString(br);
header.MimeType = UnpackString(br);
header.Created = DateTimeOffset.FromUnixTimeMilliseconds(UnpackInt64(br));
header.Iv = UnpackBytes(br);
header.CipherMetadata = UnpackBytes(br);
if (header.CipherMetadata != null && header.CipherMetadata.Length > 0)
{
metadata = Encoding.UTF8.GetString(Aes256Decrypt(key, header.Iv, header.CipherMetadata));
}
var cipherTextPosition = cipherTextStream.Position;
cipherTextStream.Seek(signaturePosition + 32 + 4, SeekOrigin.Begin);
var signingKey = key;
var signatureCompare = HmacSha256Hash(signingKey, cipherTextStream);
if (signatureCompare.SequenceEqual(header.Signature) == false)
{
throw new Exception("Signature comparison failed.");
}
using (var aes = Aes.Create())
{
aes.Key = key;
aes.IV = header.Iv;
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
cipherTextStream.Seek((int)cipherTextPosition, SeekOrigin.Begin);
using (var decryptor = aes.CreateDecryptor(key, header.Iv))
{
var cs = new CryptoStream(cipherTextStream, decryptor, CryptoStreamMode.Read);
await cs.CopyToAsync(tempUncompressStream);
await tempUncompressStream.FlushAsync();
aes.Clear();
tempUncompressStream.Seek(0, SeekOrigin.Begin);
await DecompressAsync(tempUncompressStream, plainTextStream, true);
}
}
}
return(metadata);
}
