/// <summary>
/// <para> Decrypts the symmetric key and saves it in metadata.
/// </summary>
internal static void DecryptSymmetricKey(SqlTceCipherInfoEntry?sqlTceCipherInfoEntry, string serverName, out SqlClientSymmetricKey sqlClientSymmetricKey, out SqlEncryptionKeyInfo?encryptionkeyInfoChosen)
{
Debug.Assert(serverName != null, @"serverName should not be null in DecryptSymmetricKey.");
Debug.Assert(sqlTceCipherInfoEntry.HasValue, "sqlTceCipherInfoEntry should not be null in DecryptSymmetricKey.");
Debug.Assert(sqlTceCipherInfoEntry.Value.ColumnEncryptionKeyValues != null,
"sqlTceCipherInfoEntry.ColumnEncryptionKeyValues should not be null in DecryptSymmetricKey.");
sqlClientSymmetricKey = null;
encryptionkeyInfoChosen = null;
Exception lastException = null;
SqlSymmetricKeyCache cache = SqlSymmetricKeyCache.GetInstance();
foreach (SqlEncryptionKeyInfo keyInfo in sqlTceCipherInfoEntry.Value.ColumnEncryptionKeyValues)
{
try {
if (cache.GetKey(keyInfo, serverName, out sqlClientSymmetricKey))
{
encryptionkeyInfoChosen = keyInfo;
break;
}
} catch (Exception e) {
lastException = e;
}
}
if (null == sqlClientSymmetricKey)
{
Debug.Assert(null != lastException, "CEK decryption failed without raising exceptions");
throw lastException;
}
Debug.Assert(encryptionkeyInfoChosen.HasValue, "encryptionkeyInfoChosen must have a value.");
}
/// <summary>
/// <para> Decrypts the symmetric key and saves it in metadata. In addition, intializes
/// the SqlClientEncryptionAlgorithm for rapid decryption.</para>
/// </summary>
internal static void DecryptSymmetricKey(SqlCipherMetadata md, string serverName) {
Debug.Assert(serverName != null, @"serverName should not be null in DecryptSymmetricKey.");
Debug.Assert(md != null, "md should not be null in DecryptSymmetricKey.");
Debug.Assert(md.EncryptionInfo.HasValue, "md.EncryptionInfo should not be null in DecryptSymmetricKey.");
Debug.Assert(md.EncryptionInfo.Value.ColumnEncryptionKeyValues != null, "md.EncryptionInfo.ColumnEncryptionKeyValues should not be null in DecryptSymmetricKey.");
SqlClientSymmetricKey symKey = null;
SqlEncryptionKeyInfo? encryptionkeyInfoChosen = null;
SqlSymmetricKeyCache cache = SqlSymmetricKeyCache.GetInstance();
Exception lastException = null;
foreach (SqlEncryptionKeyInfo keyInfo in md.EncryptionInfo.Value.ColumnEncryptionKeyValues) {
try {
if (cache.GetKey(keyInfo, serverName, out symKey)) {
encryptionkeyInfoChosen = keyInfo;
break;
}
} catch (Exception e) {
lastException = e;
}
}
if (null == symKey) {
Debug.Assert (null != lastException, "CEK decryption failed without raising exceptions");
throw lastException;
}
Debug.Assert(encryptionkeyInfoChosen.HasValue, "encryptionkeyInfoChosen must have a value.");
// Given the symmetric key instantiate a SqlClientEncryptionAlgorithm object and cache it in metadata
md.CipherAlgorithm = null;
SqlClientEncryptionAlgorithm cipherAlgorithm = null;
string algorithmName = ValidateAndGetEncryptionAlgorithmName(md.CipherAlgorithmId, md.CipherAlgorithmName); // may throw
SqlClientEncryptionAlgorithmFactoryList.GetInstance().GetAlgorithm(symKey, md.EncryptionType, algorithmName, out cipherAlgorithm); // will validate algorithm name and type
Debug.Assert(cipherAlgorithm != null);
md.CipherAlgorithm = cipherAlgorithm;
md.EncryptionKeyInfo = encryptionkeyInfoChosen;
return;
}