private byte[] UnprotectCore(byte[] protectedData, bool allowOperationsOnRevokedKeys, out UnprotectStatus status)
{
Debug.Assert(protectedData != null);
try
{
// argument & state checking
if (protectedData.Length < sizeof(uint) /* magic header */ + sizeof(Guid) /* key id */)
{
// payload must contain at least the magic header and key id
throw Error.ProtectionProvider_BadMagicHeader();
}
// Need to check that protectedData := { magicHeader || keyId || encryptorSpecificProtectedPayload }
// Parse the payload version number and key id.
uint magicHeaderFromPayload;
Guid keyIdFromPayload;
fixed(byte *pbInput = protectedData)
{
magicHeaderFromPayload = ReadBigEndian32BitInteger(pbInput);
keyIdFromPayload = Read32bitAlignedGuid(&pbInput[sizeof(uint)]);
}
// Are the magic header and version information correct?
int payloadVersion;
if (!TryGetVersionFromMagicHeader(magicHeaderFromPayload, out payloadVersion))
{
throw Error.ProtectionProvider_BadMagicHeader();
}
else if (payloadVersion != 0)
{
throw Error.ProtectionProvider_BadVersion();
}
if (_logger.IsDebugLevelEnabled())
{
_logger.PerformingUnprotectOperationToKeyWithPurposes(keyIdFromPayload, JoinPurposesForLog(Purposes));
}
// Find the correct encryptor in the keyring.
bool keyWasRevoked;
var currentKeyRing = _keyRingProvider.GetCurrentKeyRing();
var requestedEncryptor = currentKeyRing.GetAuthenticatedEncryptorByKeyId(keyIdFromPayload, out keyWasRevoked);
if (requestedEncryptor == null)
{
_logger?.KeyWasNotFoundInTheKeyRingUnprotectOperationCannotProceed(keyIdFromPayload);
throw Error.Common_KeyNotFound(keyIdFromPayload);
}
// Do we need to notify the caller that he should reprotect the data?
status = UnprotectStatus.Ok;
if (keyIdFromPayload != currentKeyRing.DefaultKeyId)
{
status = UnprotectStatus.DefaultEncryptionKeyChanged;
}
// Do we need to notify the caller that this key was revoked?
if (keyWasRevoked)
{
if (allowOperationsOnRevokedKeys)
{
_logger?.KeyWasRevokedCallerRequestedUnprotectOperationProceedRegardless(keyIdFromPayload);
status = UnprotectStatus.DecryptionKeyWasRevoked;
}
else
{
_logger?.KeyWasRevokedUnprotectOperationCannotProceed(keyIdFromPayload);
throw Error.Common_KeyRevoked(keyIdFromPayload);
}
}
// Perform the decryption operation.
ArraySegment <byte> ciphertext = new ArraySegment <byte>(protectedData, sizeof(uint) + sizeof(Guid), protectedData.Length - (sizeof(uint) + sizeof(Guid))); // chop off magic header + encryptor id
ArraySegment <byte> additionalAuthenticatedData = new ArraySegment <byte>(_aadTemplate.GetAadForKey(keyIdFromPayload, isProtecting: false));
// At this point, cipherText := { encryptorSpecificPayload },
// so all that's left is to invoke the decryption routine directly.
return(requestedEncryptor.Decrypt(ciphertext, additionalAuthenticatedData)
?? CryptoUtil.Fail <byte[]>("IAuthenticatedEncryptor.Decrypt returned null."));
}
catch (Exception ex) when(ex.RequiresHomogenization())
{
// homogenize all failures to CryptographicException
throw Error.DecryptionFailed(ex);
}
}
private byte[] UnprotectCore(byte[] protectedData, bool allowOperationsOnRevokedKeys, out UnprotectStatus status)
{
Debug.Assert(protectedData != null);
try
{
// argument & state checking
if (protectedData.Length < sizeof(uint) /* magic header */ + sizeof(Guid) /* key id */)
{
// payload must contain at least the magic header and key id
throw Error.ProtectionProvider_BadMagicHeader();
}
// Need to check that protectedData := { magicHeader || keyId || encryptorSpecificProtectedPayload }
// Parse the payload version number and key id.
uint magicHeaderFromPayload;
Guid keyIdFromPayload;
fixed (byte* pbInput = protectedData)
{
magicHeaderFromPayload = ReadBigEndian32BitInteger(pbInput);
keyIdFromPayload = Read32bitAlignedGuid(&pbInput[sizeof(uint)]);
}
// Are the magic header and version information correct?
int payloadVersion;
if (!TryGetVersionFromMagicHeader(magicHeaderFromPayload, out payloadVersion))
{
throw Error.ProtectionProvider_BadMagicHeader();
}
else if (payloadVersion != 0)
{
throw Error.ProtectionProvider_BadVersion();
}
if (_logger.IsDebugLevelEnabled())
{
_logger.LogDebugF($"Performing unprotect operation to key {keyIdFromPayload:B} with purposes {JoinPurposesForLog(Purposes)}.");
}
// Find the correct encryptor in the keyring.
bool keyWasRevoked;
var currentKeyRing = _keyRingProvider.GetCurrentKeyRing();
var requestedEncryptor = currentKeyRing.GetAuthenticatedEncryptorByKeyId(keyIdFromPayload, out keyWasRevoked);
if (requestedEncryptor == null)
{
if (_logger.IsDebugLevelEnabled())
{
_logger.LogDebugF($"Key {keyIdFromPayload:B} was not found in the key ring. Unprotect operation cannot proceed.");
}
throw Error.Common_KeyNotFound(keyIdFromPayload);
}
// Do we need to notify the caller that he should reprotect the data?
status = UnprotectStatus.Ok;
if (keyIdFromPayload != currentKeyRing.DefaultKeyId)
{
status = UnprotectStatus.DefaultEncryptionKeyChanged;
}
// Do we need to notify the caller that this key was revoked?
if (keyWasRevoked)
{
if (allowOperationsOnRevokedKeys)
{
if (_logger.IsVerboseLevelEnabled())
{
_logger.LogVerboseF($"Key {keyIdFromPayload:B} was revoked. Caller requested unprotect operation proceed regardless.");
}
status = UnprotectStatus.DecryptionKeyWasRevoked;
}
else
{
if (_logger.IsVerboseLevelEnabled())
{
_logger.LogVerboseF($"Key {keyIdFromPayload:B} was revoked. Unprotect operation cannot proceed.");
}
throw Error.Common_KeyRevoked(keyIdFromPayload);
}
}
// Perform the decryption operation.
ArraySegment<byte> ciphertext = new ArraySegment<byte>(protectedData, sizeof(uint) + sizeof(Guid), protectedData.Length - (sizeof(uint) + sizeof(Guid))); // chop off magic header + encryptor id
ArraySegment<byte> additionalAuthenticatedData = new ArraySegment<byte>(_aadTemplate.GetAadForKey(keyIdFromPayload, isProtecting: false));
// At this point, cipherText := { encryptorSpecificPayload },
// so all that's left is to invoke the decryption routine directly.
return requestedEncryptor.Decrypt(ciphertext, additionalAuthenticatedData)
?? CryptoUtil.Fail<byte[]>("IAuthenticatedEncryptor.Decrypt returned null.");
}
catch (Exception ex) when (ex.RequiresHomogenization())
{
// homogenize all failures to CryptographicException
throw Error.DecryptionFailed(ex);
}
}