/// <summary>
/// Constructs a key chain by decrypting bytes returned by a previous
/// call to <see cref="Encrypt" />.
/// </summary>
/// <param name="key">The <see cref="SymmetricKey" /> to be used for decrypting.</param>
/// <param name="encrypted">The encrypted key chain.</param>
/// <exception cref="CryptographicException">Thrown if the decrypted key chain is malformed.</exception>
public KeyChain(SymmetricKey key, byte[] encrypted)
{
try
{
using (var ms = new EnhancedMemoryStream(Crypto.Decrypt(encrypted, key)))
{
if (ms.ReadInt32() != Magic)
{
throw new Exception();
}
int count;
count = ms.ReadInt32();
keys = new Dictionary <string, string>(count);
for (int i = 0; i < count; i++)
{
Add(ms.ReadString16());
}
}
}
catch (Exception e)
{
throw new CryptographicException("Key chain is malformed.", e);
}
}
public void EnhancedMemoryStream_Int32()
{
var es = new EnhancedMemoryStream();
es.WriteInt32(0);
es.WriteInt32(65121);
es.WriteInt32(0x12345678);
es.Seek(0, SeekOrigin.Begin);
Assert.AreEqual(0, es.ReadInt32());
Assert.AreEqual(65121, es.ReadInt32());
Assert.AreEqual(0x12345678, es.ReadInt32());
}
/// <summary>
/// Decrypts authentication <see cref="Credentials" /> from a
/// byte array using the specified public asymmetric private key and
/// algorithm.
/// </summary>
/// <param name="encrypted">The encrypted credential bytes.</param>
/// <param name="algorithm">The encryption algorithm.</param>
/// <param name="key">The private key.</param>
/// <returns>The decrypted <see cref="Credentials" />.</returns>
/// <remarks>
/// <note>
/// The current implementation supports only the "RSA" provider.
/// </note>
/// </remarks>
/// <exception cref="SecurityException">Thrown if the credentials are corrupt.</exception>
public static Credentials DecryptCredentials(byte[] encrypted, string algorithm, string key)
{
try
{
var decrypted = Decrypt(algorithm, key, encrypted);
using (var ms = new EnhancedMemoryStream(decrypted))
{
string realm;
string account;
string password;
if (ms.ReadInt32() != Crypto.CredentialMagic)
{
throw new SecurityException(Crypto.CorruptCredentialsMsg);
}
realm = ms.ReadString16();
account = ms.ReadString16();
password = ms.ReadString16();
return(new Credentials(realm, account, password));
}
}
catch (Exception e)
{
throw new SecurityException(Crypto.CorruptCredentialsMsg, e);
}
}
/// <summary>
/// Decrypts data encrypted using <see cref="Encrypt(SymmetricKey,byte[],int)" />.
/// </summary>
/// <param name="symmetricKey">The symmetric algorithm arguments.</param>
/// <param name="cipherText">The encrypted data.</param>
/// <returns>The decrypted result.</returns>
public static byte[] Decrypt(SymmetricKey symmetricKey, byte[] cipherText)
{
EnhancedMemoryStream input = new EnhancedMemoryStream(cipherText);
EnhancedMemoryStream ms = new EnhancedMemoryStream(cipherText.Length);
BlockDecryptor decryptor = null;
try
{
// Read the header fields
if (input.ReadInt32() != Magic)
{
throw new CryptographicException(BadFormatMsg);
}
if (input.ReadInt32() != 0)
{
throw new CryptographicException("Unsupported secure data format version.");
}
decryptor = new BlockDecryptor(symmetricKey);
// Decrypt the contents
ms.WriteBytesNoLen(decryptor.Decrypt(input.ReadBytes32()));
ms.Position = 0;
if (ms.ReadInt32() != Magic)
{
throw new CryptographicException("Secure data content is corrupt.");
}
ms.Position += 8; // Skip over the salt
return(ms.ReadBytes32());
}
finally
{
if (decryptor != null)
{
decryptor.Dispose();
}
input.Close();
ms.Close();
}
}
/// <summary>
/// Called when the server receives an unserialized request.
/// </summary>
/// <param name="requestBytes">The serialized request.</param>
private void OnRequest(byte[] requestBytes)
{
try
{
using (var input = new EnhancedMemoryStream(requestBytes))
{
int typeCode = input.ReadInt32();
SharedMemMessage request;
SharedMemMessage response;
if (typeCode < 0)
{
request = new SharedMemErrorMessage();
}
else
{
request = messageFactory.Create(typeCode);
}
request.InternalReadFrom(input);
request.ReadFrom(input);
try
{
response = requestHandler(request);
if (response == null)
{
throw new NullReferenceException("Server request handler returned a NULL response message.");
}
}
catch (Exception e)
{
response = new SharedMemErrorMessage();
response.InternalError = string.Format("{0}: {1}", e.GetType().FullName, e.Message);
}
response.InternalRequestId = request.InternalRequestId;
response.InternalClientInbox = request.InternalClientInbox;
using (var output = new EnhancedMemoryStream(response.SerializedCapacityHint))
{
output.WriteInt32(response.TypeCode);
response.InternalWriteTo(output);
response.WriteTo(output);
// This call is synchronous but should execute very quickly (microseconds).
outbox.Send(response.InternalClientInbox, output.ToArray());
}
}
}
catch (Exception e)
{
SysLog.LogException(e);
}
}
/// <summary>
/// Called when the client receives a response.
/// </summary>
/// <param name="responseBytes">The serialized response.</param>
private void OnResponse(byte[] responseBytes)
{
try
{
using (var input = new EnhancedMemoryStream(responseBytes))
{
int typeCode = input.ReadInt32();
SharedMemMessage response;
PendingOperation operation;
if (typeCode < 0)
{
response = new SharedMemErrorMessage();
}
else
{
response = messageFactory.Create(typeCode);
}
response.InternalReadFrom(input);
response.ReadFrom(input);
lock (syncLock)
{
if (!pendingOperations.TryGetValue(response.InternalRequestId, out operation))
{
// The response received does not correlate to a pending operation
// (probably due to the client side timing it out). We'll just
// ignore it.
return;
}
}
if (response.InternalError != null)
{
operation.Tcs.TrySetException(new SharedMemException(response.InternalError));
}
else
{
operation.Tcs.TrySetResult(response);
}
}
}
catch (Exception e)
{
SysLog.LogException(e);
}
}
/// <summary>
/// Verifies request arguments against a signature using a shared <see cref="SymmetricKey" />
/// and the current time.
/// </summary>
/// <param name="sharedKey">The shared <see cref="SymmetricKey" />.</param>
/// <param name="signature">The base-64 encoded signature.</param>
/// <param name="args">The request argument collection.</param>
/// <param name="signatureKey">
/// The name of the signature key within the event arguments or <c>null</c>
/// if the signature is not present.
/// </param>
/// <param name="graceInterval">Specifies the time period used for verifying the signature request time.</param>
/// <returns><c>true</c> if the signature is valid.</returns>
/// <remarks>
/// <para>
/// <paramref name="graceInterval" /> is used when comparing the request time (UTC) embedded
/// in the signature with the current machine time (UTC). Request times within the range of:
/// </para>
/// <code language="none">
/// DateTime.UtcNow - graceInterval <= requestTime <= DateTime.UtcNow + graceInterval
/// </code>
/// <para>
/// will be considered to be valid. Request times outside this range will be invalid.
/// Larger grace intervals provide help avoid the problems of incorrect system times or
/// long request delivery delays but at the price of the increased exposure to replay
/// attacks.
/// </para>
/// <note>
/// If the signature is present in the arguments, then the <paramref name="signatureKey" /> <b>must</b>
/// be passed as its name or else the verification will always fail. The reason for this is
/// that the hash was originally computed before the signature was added so the hash will be
/// different if it includes the signature.
/// </note>
/// </remarks>
public static bool TryVerify(SymmetricKey sharedKey, string signature, ArgCollection args, string signatureKey, TimeSpan graceInterval)
{
try
{
byte[] encrypted = Convert.FromBase64String(signature);
byte[] decrypted;
byte[] requestHash;
byte[] hash;
DateTime requestTime;
DateTime now;
decrypted = Crypto.Decrypt(encrypted, sharedKey);
if (decrypted.Length != Size)
{
return(false);
}
using (var ms = new EnhancedMemoryStream(decrypted))
{
ms.Position = 8;
if (ms.ReadInt32() != Magic)
{
return(false);
}
requestTime = new DateTime(ms.ReadInt64());
requestHash = ms.ReadBytes(SHA1Hasher.DigestSize);
}
now = DateTime.UtcNow;
if (!Helper.Within(requestTime, now, graceInterval))
{
return(false);
}
hash = ComputeHash(args, signatureKey);
return(Helper.ArrayEquals(requestHash, hash));
}
catch
{
return(false);
}
}
/// <summary>
/// Decrypts the password change parameters encrypted by <see cref="EncryptPasswordChange" />.
/// </summary>
/// <param name="encryptedPasswords">The encryoted password change parameters.</param>
/// <param name="originalPassword">Returns as the original password.</param>
/// <param name="newPassword">Returns as the new password.</param>
/// <remarks>
/// <note>
/// This method is designed to provide a low level of security during development
/// and testing, when the overhead of configuring SSL certificates is not worth
/// the trouble. Do not rely on this method as your only mechanism for securing
/// credentials during transmission in production environments.
/// </note>
/// </remarks>
/// <exception cref="SecurityException">Thrown if the parameters are corrupt.</exception>
public static void DecryptPasswordChange(byte[] encryptedPasswords, out string originalPassword, out string newPassword)
{
try
{
var decrypted = DecryptWithSalt8(encryptedPasswords, credentialsKey);
using (var ms = new EnhancedMemoryStream(decrypted))
{
if (ms.ReadInt32() != CredentialMagic)
{
throw new SecurityException(CorruptCredentialsMsg);
}
originalPassword = ms.ReadString16();
newPassword = ms.ReadString16();
}
}
catch (Exception e)
{
throw new SecurityException(CorruptCredentialsMsg, e);
}
}
/// <summary>
/// Decrypts a byte array encrypted using <see cref="Encrypt(string ,byte[],string,int,int,out SymmetricKey)" />.
/// </summary>
/// <param name="rsaKey">The decrypting RSA key as XML or as a secure key container name.</param>
/// <param name="cipherText">The encrypted data.</param>
/// <param name="symmetricKey">Returns as the symmetric encryption algorithm arguments.</param>
/// <returns>The decrypted data.</returns>
/// <exception cref="CryptographicException">Thrown is the encrypted data block is incorrectly formatted.</exception>
/// <remarks>
/// Note that applications should take some care to ensure that the <paramref name="symmetricKey" />
/// value return is disposed so that the symmetric encryption key will be cleared.
/// </remarks>
public static byte[] Decrypt(string rsaKey, byte[] cipherText, out SymmetricKey symmetricKey)
{
EnhancedMemoryStream input = new EnhancedMemoryStream(cipherText);
EnhancedMemoryStream ms = new EnhancedMemoryStream(cipherText.Length);
BlockDecryptor decryptor = null;
byte[] symKey;
byte[] symIV;
string algorithm;
try
{
// Read the header fields
if (input.ReadInt32() != Magic)
{
throw new CryptographicException(BadFormatMsg);
}
if (input.ReadInt32() != 0)
{
throw new CryptographicException("Unsupported secure data format version.");
}
// Decrypt the encryption info
ms.WriteBytesNoLen(AsymmetricCrypto.Decrypt(CryptoAlgorithm.RSA, rsaKey, input.ReadBytes16()));
ms.Position = 0;
algorithm = ms.ReadString16();
symKey = ms.ReadBytes16();
symIV = ms.ReadBytes16();
symmetricKey = new SymmetricKey(algorithm, symKey, symIV);
decryptor = new BlockDecryptor(algorithm, symKey, symIV);
// Decrypt the contents
ms.SetLength(0);
ms.WriteBytesNoLen(decryptor.Decrypt(input.ReadBytes32()));
ms.Position = 0;
if (ms.ReadInt32() != Magic)
{
throw new CryptographicException("Secure data content is corrupt.");
}
ms.Position += 8; // Skip over the salt
return(ms.ReadBytes32());
}
finally
{
if (decryptor != null)
{
decryptor.Dispose();
}
input.Close();
ms.Close();
}
}
