private string GetCacheLookupKey(string masterKeyPath, bool allowEnclaveComputations, byte[] signature, string keyStoreName)
{
StringBuilder cacheLookupKeyBuilder = new StringBuilder(keyStoreName,
capacity:
keyStoreName.Length +
masterKeyPath.Length +
SqlSecurityUtility.GetBase64LengthFromByteLength(signature.Length) +
3 /*separators*/ +
10 /*boolean value + somebuffer*/);
cacheLookupKeyBuilder.Append(_cacheLookupKeySeparator);
cacheLookupKeyBuilder.Append(masterKeyPath);
cacheLookupKeyBuilder.Append(_cacheLookupKeySeparator);
cacheLookupKeyBuilder.Append(allowEnclaveComputations);
cacheLookupKeyBuilder.Append(_cacheLookupKeySeparator);
cacheLookupKeyBuilder.Append(Convert.ToBase64String(signature));
cacheLookupKeyBuilder.Append(_cacheLookupKeySeparator);
string cacheLookupKey = cacheLookupKeyBuilder.ToString();
return(cacheLookupKey);
}
/// <summary>
/// <para> Retrieves Symmetric Key (in plaintext) given the encryption material.</para>
/// </summary>
internal bool GetKey(SqlEncryptionKeyInfo keyInfo, string serverName, out SqlClientSymmetricKey encryptionKey)
{
Debug.Assert(serverName != null, @"serverName should not be null.");
StringBuilder cacheLookupKeyBuilder = new StringBuilder(serverName, capacity: serverName.Length + SqlSecurityUtility.GetBase64LengthFromByteLength(keyInfo.encryptedKey.Length) + keyInfo.keyStoreName.Length + 2 /*separators*/);
#if DEBUG
int capacity = cacheLookupKeyBuilder.Capacity;
#endif //DEBUG
cacheLookupKeyBuilder.Append(":");
cacheLookupKeyBuilder.Append(Convert.ToBase64String(keyInfo.encryptedKey));
cacheLookupKeyBuilder.Append(":");
cacheLookupKeyBuilder.Append(keyInfo.keyStoreName);
string cacheLookupKey = cacheLookupKeyBuilder.ToString();
#if DEBUG
Debug.Assert(cacheLookupKey.Length <= capacity, "We needed to allocate a larger array");
#endif //DEBUG
// Lookup the key in cache
encryptionKey = _cache.Get(cacheLookupKey) as SqlClientSymmetricKey;
if (encryptionKey == null)
{
Debug.Assert(SqlConnection.ColumnEncryptionTrustedMasterKeyPaths != null, @"SqlConnection.ColumnEncryptionTrustedMasterKeyPaths should not be null");
// Check against the trusted key paths
//
// Get the List corresponding to the connected server
IList <string> trustedKeyPaths;
if (SqlConnection.ColumnEncryptionTrustedMasterKeyPaths.TryGetValue(serverName, out trustedKeyPaths))
{
// If the list is null or is empty or if the keyPath doesn't exist in the trusted key paths, then throw an exception.
if ((trustedKeyPaths == null) || (trustedKeyPaths.Count() == 0) ||
// (trustedKeyPaths.Where(s => s.Equals(keyInfo.keyPath, StringComparison.InvariantCultureIgnoreCase)).Count() == 0)) {
(trustedKeyPaths.Any(s => s.Equals(keyInfo.keyPath, StringComparison.InvariantCultureIgnoreCase)) == false))
{
// throw an exception since the key path is not in the trusted key paths list for this server
throw SQL.UntrustedKeyPath(keyInfo.keyPath, serverName);
}
}
// Key Not found, attempt to look up the provider and decrypt CEK
SqlColumnEncryptionKeyStoreProvider provider;
if (!SqlConnection.TryGetColumnEncryptionKeyStoreProvider(keyInfo.keyStoreName, out provider))
{
throw SQL.UnrecognizedKeyStoreProviderName(keyInfo.keyStoreName,
SqlConnection.GetColumnEncryptionSystemKeyStoreProviders(),
SqlConnection.GetColumnEncryptionCustomKeyStoreProviders());
}
// Decrypt the CEK
// We will simply bubble up the exception from the DecryptColumnEncryptionKey function.
byte[] plaintextKey;
try {
plaintextKey = provider.DecryptColumnEncryptionKey(keyInfo.keyPath, keyInfo.algorithmName, keyInfo.encryptedKey);
}
catch (Exception e) {
// Generate a new exception and throw.
string keyHex = SqlSecurityUtility.GetBytesAsString(keyInfo.encryptedKey, fLast: true, countOfBytes: 10);
throw SQL.KeyDecryptionFailed(keyInfo.keyStoreName, keyHex, e);
}
encryptionKey = new SqlClientSymmetricKey(plaintextKey);
// If the cache TTL is zero, don't even bother inserting to the cache.
if (SqlConnection.ColumnEncryptionKeyCacheTtl != TimeSpan.Zero)
{
// In case multiple threads reach here at the same time, the first one wins.
// The allocated memory will be reclaimed by Garbage Collector.
DateTimeOffset expirationTime = DateTimeOffset.UtcNow.Add(SqlConnection.ColumnEncryptionKeyCacheTtl);
_cache.Add(cacheLookupKey, encryptionKey, expirationTime);
}
}
return(true);
}
/// <summary>
/// Creates an instance of SqlAes256CbcAlgorithm class with a given key
/// </summary>
/// <param name="encryptionKey">Root key</param>
/// <param name="encryptionType">Encryption Type. Expected values are either Determinitic or Randomized.</param>
/// <param name="encryptionAlgorithm">Encryption Algorithm.</param>
/// <returns></returns>
internal override SqlClientEncryptionAlgorithm Create(SqlClientSymmetricKey encryptionKey, SqlClientEncryptionType encryptionType, string encryptionAlgorithm)
{
// Callers should have validated the encryption algorithm and the encryption key
Debug.Assert(encryptionKey != null);
Debug.Assert(string.Equals(encryptionAlgorithm, SqlAes256CbcAlgorithm.AlgorithmName, StringComparison.OrdinalIgnoreCase) == true);
// Validate encryption type
if (!((encryptionType == SqlClientEncryptionType.Deterministic) || (encryptionType == SqlClientEncryptionType.Randomized)))
{
throw SQL.InvalidEncryptionType(SqlAes256CbcAlgorithm.AlgorithmName,
encryptionType,
SqlClientEncryptionType.Deterministic,
SqlClientEncryptionType.Randomized);
}
// Get the cached encryption algorithm if one exists or create a new one, add it to cache and use it
//
// For now, we only have one version. In future, we may need to parse the algorithm names to derive the version byte.
const byte algorithmVersion = 0x1;
StringBuilder algorithmKeyBuilder = new StringBuilder(Convert.ToBase64String(encryptionKey.RootKey), SqlSecurityUtility.GetBase64LengthFromByteLength(encryptionKey.RootKey.Length) + 4 /*separators, type and version*/);
#if DEBUG
int capacity = algorithmKeyBuilder.Capacity;
#endif //DEBUG
algorithmKeyBuilder.Append(":");
algorithmKeyBuilder.Append((int)encryptionType);
algorithmKeyBuilder.Append(":");
algorithmKeyBuilder.Append(algorithmVersion);
string algorithmKey = algorithmKeyBuilder.ToString();
#if DEBUG
Debug.Assert(algorithmKey.Length <= capacity, "We needed to allocate a larger array");
#endif //DEBUG
SqlAes256CbcAlgorithm aesAlgorithm;
if (!_encryptionAlgorithms.TryGetValue(algorithmKey, out aesAlgorithm))
{
SqlAeadAes256CbcHmac256EncryptionKey encryptedKey = new SqlAeadAes256CbcHmac256EncryptionKey(encryptionKey.RootKey, SqlAes256CbcAlgorithm.AlgorithmName);
aesAlgorithm = new SqlAes256CbcAlgorithm(encryptedKey, encryptionType, algorithmVersion);
// In case multiple threads reach here at the same time, the first one adds the value
// the second one will be a no-op, the allocated memory will be claimed by Garbage Collector.
_encryptionAlgorithms.TryAdd(algorithmKey, aesAlgorithm);
}
return(aesAlgorithm);
}