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Aesgcm
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@RojaEnnam
RojaEnnam committed Mar 3, 2021
1 parent 705da5b commit f2b7a2d
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Showing 16 changed files with 854 additions and 66 deletions.
2 changes: 1 addition & 1 deletion src/Microsoft.IdentityModel.JsonWebTokens/JsonWebTokenHandler.cs
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Expand Up @@ -751,7 +751,7 @@ private static string EncryptTokenPrivate(string innerJwt, EncryptingCredentials
throw LogHelper.LogExceptionMessage(new ArgumentException(TokenLogMessages.IDX10620));

byte[] wrappedKey = null;
SecurityKey securityKey = JwtTokenUtilities.GetSecurityKey(encryptingCredentials,cryptoProviderFactory, out wrappedKey);
SecurityKey securityKey = JwtTokenUtilities.GetSecurityKey(encryptingCredentials, cryptoProviderFactory, out wrappedKey);

using (var encryptionProvider = cryptoProviderFactory.CreateAuthenticatedEncryptionProvider(securityKey, encryptingCredentials.Enc))
{
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2 changes: 1 addition & 1 deletion src/Microsoft.IdentityModel.Tokens/CryptoProviderFactory.cs
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Expand Up @@ -162,7 +162,7 @@ public virtual AuthenticatedEncryptionProvider CreateAuthenticatedEncryptionProv
return cryptoProvider;
}

if (SupportedAlgorithms.IsSupportedAuthenticatedEncryptionAlgorithm(algorithm, key))
if (SupportedAlgorithms.IsSupportedAuthenticatedEncryptionAlgorithm(algorithm, key) || SupportedAlgorithms.IsSupportedAesGcmEncryptionAlgorithm(algorithm, key))
return new AuthenticatedEncryptionProvider(key, algorithm);

throw LogHelper.LogExceptionMessage(new ArgumentException(LogHelper.FormatInvariant(LogMessages.IDX10652, algorithm), nameof(algorithm)));
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36 changes: 36 additions & 0 deletions src/Microsoft.IdentityModel.Tokens/Encryption/AesGcm.cs
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@@ -0,0 +1,36 @@
using System;

namespace Microsoft.IdentityModel.Tokens
{
internal class AesGcm : IDisposable
{
public const int NonceSize = 12;
public const int TagSize = 16;

private static readonly SafeAlgorithmHandle s_aesGcm = AesBCryptModes.OpenAesAlgorithm(Cng.BCRYPT_CHAIN_MODE_GCM).Value;
private SafeKeyHandle _keyHandle;
public AesGcm(byte[] key)
{
if (key == null)
throw new ArgumentNullException(nameof(key));

ImportKey(key);
}

private void ImportKey(byte[] key)
{
_keyHandle = Interop.BCrypt.BCryptImportKey(s_aesGcm, key);
}

public void Dispose()
{
_keyHandle.Dispose();
}

public void Decrypt(byte[] nonce, byte[] ciphertext, byte[] tag, byte[] plaintext, byte[] associatedData = null)
{
AesAEAD.CheckArgumentsForNull(nonce, plaintext, ciphertext, tag);
AesAEAD.Decrypt(_keyHandle, nonce, associatedData, ciphertext, tag, plaintext, clearPlaintextOnFailure: true);
}
}
}
189 changes: 133 additions & 56 deletions src/Microsoft.IdentityModel.Tokens/Encryption/AuthenticatedEncryptionProvider.cs
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Expand Up @@ -32,6 +32,9 @@

namespace Microsoft.IdentityModel.Tokens
{
delegate AuthenticatedEncryptionResult EncryptionDelegate(byte[] plaintText, byte[] authenticatedData, byte[] iv);
delegate byte[] DecryptionDelegate(byte[] cipherText, byte[] authenticatedData, byte[] iv, byte[] authenticationTag);

/// <summary>
/// Provides authenticated encryption and decryption services.
/// </summary>
Expand All @@ -48,6 +51,8 @@ private struct AuthenticatedKeys
private bool _disposed;
private string _hmacAlgorithm;
private Lazy<SymmetricSignatureProvider> _symmetricSignatureProvider;
private DecryptionDelegate DecryptFunction;
private EncryptionDelegate EncryptFunction;

/// <summary>
/// Initializes a new instance of the <see cref="AuthenticatedEncryptionProvider"/> class used for encryption and decryption.
Expand All @@ -67,20 +72,117 @@ public AuthenticatedEncryptionProvider(SecurityKey key, string algorithm)
if (string.IsNullOrWhiteSpace(algorithm))
throw LogHelper.LogArgumentNullException(nameof(algorithm));

_authenticatedkeys = new Lazy<AuthenticatedKeys>(CreateAuthenticatedKeys);
_hmacAlgorithm = GetHmacAlgorithm(algorithm);
Key = key;
Algorithm = algorithm;
_cryptoProviderFactory = key.CryptoProviderFactory;

if (SupportedAlgorithms.IsSupportedAesGcmEncryptionAlgorithm(algorithm, key))
{
#if NET_CORE
if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
throw LogHelper.LogExceptionMessage(new PlatformNotSupportedException(LogHelper.FormatInvariant(LogMessages.IDX10713, algorithm)));
#endif
InitializeUsingAesGcm();
}
else if (SupportedAlgorithms.IsSupportedAuthenticatedEncryptionAlgorithm(algorithm, key))
InitializeUsingAesCbc();
else
throw LogHelper.LogExceptionMessage(new ArgumentException(LogHelper.FormatInvariant(LogMessages.IDX10668, GetType(), algorithm, key)));
}

private void InitializeUsingAesGcm()
{
ValidateKeySize(Key, Algorithm);
EncryptFunction = EncryptWithAesGcm;
DecryptFunction = DecryptWithAesGcm;
}

private void InitializeUsingAesCbc()
{
_authenticatedkeys = new Lazy<AuthenticatedKeys>(CreateAuthenticatedKeys);
_hmacAlgorithm = GetHmacAlgorithm(Algorithm);
_symmetricSignatureProvider = new Lazy<SymmetricSignatureProvider>(CreateSymmetricSignatureProvider);
EncryptFunction = EncryptWithAesCbc;
DecryptFunction = DecryptWithAesCbc;
}

private AuthenticatedKeys CreateAuthenticatedKeys()
private AuthenticatedEncryptionResult EncryptWithAesGcm(byte[] plaintext, byte[] authenticatedData, byte[] iv)
{
if (!IsSupportedAlgorithm(Key, Algorithm))
throw LogHelper.LogExceptionMessage(new ArgumentException(LogHelper.FormatInvariant(LogMessages.IDX10668, GetType(), Algorithm, Key)));
throw LogHelper.LogExceptionMessage(new NotSupportedException(LogHelper.FormatInvariant(LogMessages.IDX10699, Algorithm)));
}

private byte[] DecryptWithAesGcm(byte[] ciphertext, byte[] authenticatedData, byte[] iv, byte[] authenticationTag)
{
byte[] clearBytes = new byte[ciphertext.Length];
using (var aes = new AesGcm(GetKeyBytes(Key)))
{
aes.Decrypt(iv, ciphertext, authenticationTag, clearBytes, authenticatedData);
}

return clearBytes;
}

private AuthenticatedEncryptionResult EncryptWithAesCbc(byte[] plaintext, byte[] authenticatedData, byte[] iv)
{
using Aes aes = Aes.Create();
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
aes.Key = _authenticatedkeys.Value.AesKey.Key;
if (iv != null)
aes.IV = iv;

byte[] ciphertext;
try
{
ciphertext = Transform(aes.CreateEncryptor(), plaintext, 0, plaintext.Length);
}
catch (Exception ex)
{
throw LogHelper.LogExceptionMessage(new SecurityTokenEncryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10654, ex)));
}

byte[] al = Utility.ConvertToBigEndian(authenticatedData.Length * 8);
byte[] macBytes = new byte[authenticatedData.Length + aes.IV.Length + ciphertext.Length + al.Length];
Array.Copy(authenticatedData, 0, macBytes, 0, authenticatedData.Length);
Array.Copy(aes.IV, 0, macBytes, authenticatedData.Length, aes.IV.Length);
Array.Copy(ciphertext, 0, macBytes, authenticatedData.Length + aes.IV.Length, ciphertext.Length);
Array.Copy(al, 0, macBytes, authenticatedData.Length + aes.IV.Length + ciphertext.Length, al.Length);
byte[] macHash = _symmetricSignatureProvider.Value.Sign(macBytes);
var authenticationTag = new byte[_authenticatedkeys.Value.HmacKey.Key.Length];
Array.Copy(macHash, authenticationTag, authenticationTag.Length);

return new AuthenticatedEncryptionResult(Key, ciphertext, aes.IV, authenticationTag);
}

private byte[] DecryptWithAesCbc(byte[] ciphertext, byte[] authenticatedData, byte[] iv, byte[] authenticationTag)
{
// Verify authentication Tag
byte[] al = Utility.ConvertToBigEndian(authenticatedData.Length * 8);
byte[] macBytes = new byte[authenticatedData.Length + iv.Length + ciphertext.Length + al.Length];
Array.Copy(authenticatedData, 0, macBytes, 0, authenticatedData.Length);
Array.Copy(iv, 0, macBytes, authenticatedData.Length, iv.Length);
Array.Copy(ciphertext, 0, macBytes, authenticatedData.Length + iv.Length, ciphertext.Length);
Array.Copy(al, 0, macBytes, authenticatedData.Length + iv.Length + ciphertext.Length, al.Length);
if (!_symmetricSignatureProvider.Value.Verify(macBytes, authenticationTag, _authenticatedkeys.Value.HmacKey.Key.Length))
throw LogHelper.LogExceptionMessage(new SecurityTokenDecryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10650, Base64UrlEncoder.Encode(authenticatedData), Base64UrlEncoder.Encode(iv), Base64UrlEncoder.Encode(authenticationTag))));

using Aes aes = Aes.Create();
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
aes.Key = _authenticatedkeys.Value.AesKey.Key;
aes.IV = iv;
try
{
return Transform(aes.CreateDecryptor(), ciphertext, 0, ciphertext.Length);
}
catch (Exception ex)
{
throw LogHelper.LogExceptionMessage(new SecurityTokenDecryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10654, ex)));
}
}

private AuthenticatedKeys CreateAuthenticatedKeys()
{
ValidateKeySize(Key, Algorithm);

return GetAlgorithmParameters(Key, Algorithm);
Expand Down Expand Up @@ -158,34 +260,7 @@ public virtual AuthenticatedEncryptionResult Encrypt(byte[] plaintext, byte[] au
if (_disposed)
throw LogHelper.LogExceptionMessage(new ObjectDisposedException(GetType().ToString()));

using Aes aes = Aes.Create();
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
aes.Key = _authenticatedkeys.Value.AesKey.Key;
if (iv != null)
aes.IV = iv;

byte[] ciphertext;
try
{
ciphertext = Transform(aes.CreateEncryptor(), plaintext, 0, plaintext.Length);
}
catch(Exception ex)
{
throw LogHelper.LogExceptionMessage(new SecurityTokenEncryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10654, ex)));
}

byte[] al = Utility.ConvertToBigEndian(authenticatedData.Length * 8);
byte[] macBytes = new byte[authenticatedData.Length + aes.IV.Length + ciphertext.Length + al.Length];
Array.Copy(authenticatedData, 0, macBytes, 0, authenticatedData.Length);
Array.Copy(aes.IV, 0, macBytes, authenticatedData.Length, aes.IV.Length);
Array.Copy(ciphertext, 0, macBytes, authenticatedData.Length + aes.IV.Length, ciphertext.Length);
Array.Copy(al, 0, macBytes, authenticatedData.Length + aes.IV.Length + ciphertext.Length, al.Length);
byte[] macHash = _symmetricSignatureProvider.Value.Sign(macBytes);
var authenticationTag = new byte[_authenticatedkeys.Value.HmacKey.Key.Length];
Array.Copy(macHash, authenticationTag, authenticationTag.Length);

return new AuthenticatedEncryptionResult(Key, ciphertext, aes.IV, authenticationTag);
return EncryptFunction(plaintext, authenticatedData, iv);
}

/// <summary>
Expand Down Expand Up @@ -220,29 +295,7 @@ public virtual byte[] Decrypt(byte[] ciphertext, byte[] authenticatedData, byte[
if (_disposed)
throw LogHelper.LogExceptionMessage(new ObjectDisposedException(GetType().ToString()));

// Verify authentication Tag
byte[] al = Utility.ConvertToBigEndian(authenticatedData.Length * 8);
byte[] macBytes = new byte[authenticatedData.Length + iv.Length + ciphertext.Length + al.Length];
Array.Copy(authenticatedData, 0, macBytes, 0, authenticatedData.Length);
Array.Copy(iv, 0, macBytes, authenticatedData.Length, iv.Length);
Array.Copy(ciphertext, 0, macBytes, authenticatedData.Length + iv.Length, ciphertext.Length);
Array.Copy(al, 0, macBytes, authenticatedData.Length + iv.Length + ciphertext.Length, al.Length);
if (!_symmetricSignatureProvider.Value.Verify(macBytes, authenticationTag, _authenticatedkeys.Value.HmacKey.Key.Length))
throw LogHelper.LogExceptionMessage(new SecurityTokenDecryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10650, Base64UrlEncoder.Encode(authenticatedData), Base64UrlEncoder.Encode(iv), Base64UrlEncoder.Encode(authenticationTag))));

using Aes aes = Aes.Create();
aes.Mode = CipherMode.CBC;
aes.Padding = PaddingMode.PKCS7;
aes.Key = _authenticatedkeys.Value.AesKey.Key;
aes.IV = iv;
try
{
return Transform(aes.CreateDecryptor(), ciphertext, 0, ciphertext.Length);
}
catch (Exception ex)
{
throw LogHelper.LogExceptionMessage(new SecurityTokenDecryptionFailedException(LogHelper.FormatInvariant(LogMessages.IDX10654, ex)));
}
return DecryptFunction(ciphertext, authenticatedData, iv, authenticationTag);
}

/// <summary>
Expand Down Expand Up @@ -404,6 +457,30 @@ protected virtual void ValidateKeySize(SecurityKey key, string algorithm)
return;
}

if (SecurityAlgorithms.Aes128Gcm.Equals(algorithm, StringComparison.Ordinal))
{
if (key.KeySize < 128)
throw LogHelper.LogExceptionMessage(new ArgumentOutOfRangeException(nameof(key), LogHelper.FormatInvariant(LogMessages.IDX10653, SecurityAlgorithms.Aes128Gcm, 128, key.KeyId, key.KeySize)));

return;
}

if (SecurityAlgorithms.Aes192Gcm.Equals(algorithm, StringComparison.Ordinal))
{
if (key.KeySize < 192)
throw LogHelper.LogExceptionMessage(new ArgumentOutOfRangeException(nameof(key), LogHelper.FormatInvariant(LogMessages.IDX10653, SecurityAlgorithms.Aes192Gcm, 192, key.KeyId, key.KeySize)));

return;
}

if (SecurityAlgorithms.Aes256Gcm.Equals(algorithm, StringComparison.Ordinal))
{
if (key.KeySize < 256)
throw LogHelper.LogExceptionMessage(new ArgumentOutOfRangeException(nameof(key), LogHelper.FormatInvariant(LogMessages.IDX10653, SecurityAlgorithms.Aes256Gcm, 256, key.KeyId, key.KeySize)));

return;
}

throw LogHelper.LogExceptionMessage(new ArgumentException(LogHelper.FormatInvariant(LogMessages.IDX10652, algorithm)));
}
}
Expand Down
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