internal static void ValidateEncryptionAlgorithm(KeyEncryptionKeyAlgorithm encryptionAlgorithm)
{
if (encryptionAlgorithm != KeyEncryptionKeyAlgorithm.RSA_OAEP)
{
throw new MicrosoftDataEncryptionException(InvalidKeyAlgorithm.FormatInvariant(encryptionAlgorithm, KeyEncryptionKeyAlgorithm.RSA_OAEP.ToString()));
}
}
/// <summary>
/// This function uses the asymmetric key specified by the key path
/// and encrypts an unencrypted data encryption key with RSA encryption algorithm.
/// </summary>
/// <param name="encryptionKeyId">Identifier of an asymmetric key in Azure Key Vault</param>
/// <param name="algorithm">The encryption algorithm.</param>
/// <param name="key">The plaintext key.</param>
/// <returns>Encrypted data encryption key</returns>
public override byte[] WrapKey(string encryptionKeyId, KeyEncryptionKeyAlgorithm algorithm, byte[] key)
{
// Validate the input parameters
ValidateNonEmptyAKVPath(encryptionKeyId, isSystemOp: true);
ValidateEncryptionAlgorithm(algorithm);
key.ValidateNotNull(nameof(key));
ValidateDataEncryptionKeyNotEmpty(key);
// Also validates whether the key is RSA one or not and then get the key size
KeyCryptographer.AddKey(encryptionKeyId);
int keySizeInBytes = KeyCryptographer.GetKeySize(encryptionKeyId);
// Construct the encryptedDataEncryptionKey
// Format is
// firstVersion + keyPathLength + ciphertextLength + keyPath + ciphertext + signature
// Get the Unicode encoded bytes of cultureinvariant lower case keyEncryptionKeyPath
byte[] keyEncryptionKeyPathBytes = Encoding.Unicode.GetBytes(encryptionKeyId.ToLowerInvariant());
byte[] keyPathLength = BitConverter.GetBytes((short)keyEncryptionKeyPathBytes.Length);
// Encrypt the plain text
byte[] cipherText = KeyCryptographer.WrapKey(keyWrapAlgorithm, key, encryptionKeyId);
byte[] cipherTextLength = BitConverter.GetBytes((short)cipherText.Length);
if (cipherText.Length != keySizeInBytes)
{
throw new MicrosoftDataEncryptionException(CipherTextLengthMismatch);
}
// Compute message
// SHA-2-256(version + keyPathLength + ciphertextLength + keyPath + ciphertext)
byte[] message = firstVersion.Concat(keyPathLength).Concat(cipherTextLength).Concat(keyEncryptionKeyPathBytes).Concat(cipherText).ToArray();
// Sign the message
byte[] signature = KeyCryptographer.SignData(message, encryptionKeyId);
if (signature.Length != keySizeInBytes)
{
throw new MicrosoftDataEncryptionException(HashLengthMismatch);
}
ValidateSignature(encryptionKeyId, message, signature);
return(message.Concat(signature).ToArray());
}
/// <summary>
/// This function uses the asymmetric key specified by the key path
/// and decrypts an encrypted data dencryption key with RSA encryption algorithm.
/// </summary>
/// <param name="encryptionKeyId">Identifier of an asymmetric key in Azure Key Vault</param>
/// <param name="algorithm">The encryption algorithm.</param>
/// <param name="encryptedKey">The ciphertext key.</param>
/// <returns>Plain text data encryption key</returns>
public override byte[] UnwrapKey(string encryptionKeyId, KeyEncryptionKeyAlgorithm algorithm, byte[] encryptedKey)
{
// Validate the input parameters
ValidateNonEmptyAKVPath(encryptionKeyId, isSystemOp: true);
ValidateEncryptionAlgorithm(algorithm);
encryptedKey.ValidateNotNull(nameof(encryptedKey));
encryptedKey.ValidateNotEmpty(nameof(encryptedKey));
ValidateVersionByte(encryptedKey[0], firstVersion[0]);
return(GetOrCreateDataEncryptionKey(encryptedKey.ToHexString(), DecryptEncryptionKey));
byte[] DecryptEncryptionKey()
{
// Also validates whether the key is RSA one or not and then get the key size
KeyCryptographer.AddKey(encryptionKeyId);
int keySizeInBytes = KeyCryptographer.GetKeySize(encryptionKeyId);
// Get key path length
int currentIndex = firstVersion.Length;
ushort keyPathLength = BitConverter.ToUInt16(encryptedKey, currentIndex);
currentIndex += sizeof(ushort);
// Get ciphertext length
ushort cipherTextLength = BitConverter.ToUInt16(encryptedKey, currentIndex);
currentIndex += sizeof(ushort);
// Skip KeyPath
// KeyPath exists only for troubleshooting purposes and doesnt need validation.
currentIndex += keyPathLength;
// validate the ciphertext length
if (cipherTextLength != keySizeInBytes)
{
throw new MicrosoftDataEncryptionException(InvalidCiphertextLengthTemplate.FormatInvariant(cipherTextLength, keySizeInBytes, encryptionKeyId));
}
// Validate the signature length
int signatureLength = encryptedKey.Length - currentIndex - cipherTextLength;
if (signatureLength != keySizeInBytes)
{
throw new MicrosoftDataEncryptionException(InvalidSignatureLengthTemplate.FormatInvariant(signatureLength, keySizeInBytes, encryptionKeyId));
}
// Get ciphertext
byte[] cipherText = encryptedKey.Skip(currentIndex).Take(cipherTextLength).ToArray();
currentIndex += cipherTextLength;
// Get signature
byte[] signature = encryptedKey.Skip(currentIndex).Take(signatureLength).ToArray();
// Compute the message to validate the signature
byte[] message = encryptedKey.Take(encryptedKey.Length - signatureLength).ToArray();
if (null == message)
{
throw new MicrosoftDataEncryptionException(NullHash);
}
if (!KeyCryptographer.VerifyData(message, signature, encryptionKeyId))
{
throw new MicrosoftDataEncryptionException(InvalidSignatureTemplate.FormatInvariant(encryptionKeyId));
}
return(KeyCryptographer.UnwrapKey(keyWrapAlgorithm, cipherText, encryptionKeyId));
}
}
public override byte[] WrapKey(string masterKeyPath, KeyEncryptionKeyAlgorithm encryptionAlgorithm, byte[] columnEncryptionKey)
{
throw new NotImplementedException();
}
public override byte[] UnwrapKey(string masterKeyPath, KeyEncryptionKeyAlgorithm encryptionAlgorithm, byte[] encryptedColumnEncryptionKey)
{
return(GetOrCreateDataEncryptionKey(encryptedColumnEncryptionKey.ToHexString(), DecryptEncryptionKey));
public override byte[] WrapKey(string masterKeyPath, KeyEncryptionKeyAlgorithm encryptionAlgorithm, byte[] key)
{
byte[] encryptedkey = key.Select(b => (byte)(b + 1)).ToArray();
return(encryptedkey);
}
public override byte[] UnwrapKey(string masterKeyPath, KeyEncryptionKeyAlgorithm encryptionAlgorithm, byte[] encryptedKey)
{
byte[] plainkey = encryptedKey.Select(b => (byte)(b - 1)).ToArray();
return(plainkey);
}