Rebex TLS

TLS library for modern and legacy platforms

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Release notes for Rebex TLS for .NET


R5.5 #

(build 7900 from 2021-08-17)

New binaries for .NET Core 3.1

We added a new set of binaries targeting .NET Core 3.1. We have already been supporting that platform since 2019 via .NET Standard 2.1. However, the new set of binaries utilizes .NET Core's hardware intrinsics API and features our fast ChaCha20/Poly1305 implementation that has been previously only available on .NET 5.0.

For an overview of available binaries and supported platforms, check out Rebex Support Lifecycle KB article.

Detailed list of changes:

  • All: Added 'netcoreapp3.1' binaries.

R5.4 #

(build 7888 from 2021-08-05)

Fixed parsing of TLS 1.3 Certificate messages

This release fixes parsing of TLS 1.3 Certificate handshake message spanning more than two records.

Detailed list of changes:

  • Networking: Fixed casing in 'Basic' HTTP proxy authorization header.
  • TLS Core: Fixed parsing of TLS 1.3 Certificate handshake message spanning multiple records.
  • Cryptography: Fixed Certificate.FriendlyName setter in .NET 5.0 on non-Windows platforms.

R5.3 #

(build 7840 from 2021-06-18)

Fixed FIPS-mode detection in .NET 4.8

This release fixes an issue in FIPS-mode detection routine that was not working properly in applications targeting .NET Framework 4.8 due to a change in the framework's behavior. This only affects applications targeting .NET Framework 4.8. Applications targeting earlier framework versions do not suffer from this issue even when running on .NET Framework 4.8.

If your application targets .NET Framework 4.8 and is supposed to honor system-wide FIPS mode settings, either upgrade to this release, or set Rebex.Security.Cryptography.CryptoHelper.UseFipsAlgorithmsOnly to System.Security.Cryptography.CryptoConfig.AllowOnlyFipsAlgorithms in your application's startup code.

Detailed list of changes:

  • SSH: Fixed race condition in OpenSSH-style compression startup code (occasionally caused connection failures during authentication with SSH compression was enabled).
  • TLS Core: Added SslSettings.SetPreferredSuites/GetPreferredSuites methods to make it possible to specify client-side TLS cipher preference.
  • TLS Core: Improved logging when remote party does not support TLS 1.3.
  • TLS Core: Optimized TlsSocket.Negotiate method when TLS 1.3 is enabled but not supported by the remote side.
  • TLS Core: Prevented 'unobserved' exceptions in task-based TLS 1.2 core.
  • Cryptography: Added support for private keys using PBKDF2 with HMAC/SHA-2 (RFC 8018 / PKCS #5 v2.1).
  • Cryptography: Fixed detection of FIPS-only systems on .NET Framework 4.8.
  • Cryptography: Optimized creation of algorithm objects in CNG layer.

R5.2 #

(build 7800 from 2021-05-09)

New ChaCha20Poly1305 class

This release features the new ChaCha20Poly1305 class that implements the 'combined mode' AEAD cipher consisting of ChaCha20 stream cipher and Poly1305 authenticator, as specified by RFC 7539.

Faster ChaCha20/Poly1305 on older platforms

We further improved performance of ChaCha20/Poly1305 in TLS and SSH on older platforms. It's not as fast as our .NET 5.0 implementation using AVX2 or Advanced NEON SIMD, but it's faster than ever before.

Detailed list of changes:

  • Networking: Added support for SOCKS5 servers that respond with domain name.
  • SSH: Optimized usage of ChaCha20/Poly1305 in SSH.
  • Cryptography: Added ChaCha20Poly1305 class that implements ChaCha20/Poly1305 with an API that resembles .NET's AesGcm class.
  • Cryptography: Added support for loading of ECDSA certificates from PFX/P12 files in .NET 5.0 and .NET Standard 2.1 on Linux and macOS.
  • Cryptography: Added support for saving to PFX/P12 files for certificates with temporarily associated private keys in .NET 5.0 and .NET Standard 2.1 on Linux and macOS.
  • Cryptography: AVX2 implementation of ChaCha20 releases old pre-generated keystream immediately after reinitialization.
  • Cryptography: Clearing output data in AesGcm class when authentication tag is invalid.
  • Cryptography: Fixed parsing of Cryptographic Message Syntax envelopes with unsupported OIDs.
  • Cryptography: Improved ChaCha20/Poly1305 performance on .NET 3.5-4.6 and .NET Standard 2.x.
  • Cryptography: Improved performance of AES/CTR ciphers (used in SSH).
  • Common: Improved error handling when raising events via synchronization context.

R5.1 #

(build 7733 from 2021-03-03)

Simplified release naming

We decided to drop the year from our release naming scheme. Instead of '2020 R5.1', this release is called just 'R5.1', and the forthcoming releases will use the same 'R5.x' naming scheme until the next major upgrade.

Faster ChaCha20/Poly1305 in .NET 5.0

By utilizing AVX2 (on Intel/AMD) or Advanced NEON SIMD (on ARM) via .NET's new hardware intrinsics API in .NET 5.0, we made our ChaCha20/Poly1305 implementation in SSH and TLS much faster. On ARM64, ChaCha20/Poly1305 is now even faster than Windows native AES/GCM.

This release improves ChaCha20/Poly1305 performance on older platforms as well, although not by such a big margin.

Detailed list of changes:

  • All: Changed release naming scheme ('R5.1' instead of '2020 R5.1').
  • Networking: Added workaround for rare WSAEWOULDBLOCK error on Mono in Socket.Connect.
  • Networking: More meaningful exception is throw when attempting to use HTTP CONNECT proxy with NTLM authentication on platforms that don't support it.
  • Networking: Optimized timeout infrastructure in ProxySocket.Connect.
  • SSH: Added workaround for WingFTPServer server that uses 'ssh-rsa' with SHA-2 when client announces RSA/SHA-2 support.
  • SSH: Fixed format of SshPublicKey.GetPublicKey() response for public keys initialized from PublicKeyInfo or AsymmetricAlgorithm.
  • SSH: Fixed handling of unknown channel requests (not sending reply if not requested).
  • TLS Core: Added VerifyMessage signature algorithm logging in TLS 1.3.
  • TLS Core: Close/Dispose method called on TLS 1.3 socket ensures that all outstanding IO operations are canceled before the control is returned to the caller.
  • TLS Core: Fixed possible rare NullReferenceException when closing TLS 1.3 session.
  • TLS Core: Synchronous methods on TlsSocket wrap TaskCanceledException to TlsException.
  • Cryptography: Added workaround to Certificate.LoadDer method to enable loading of certificates in PKCS #7 containers.
  • Cryptography: Enhanced implicit operator for conversion of Certificate->X509Certificate2 to retain private keys on non-Windows platforms as well.
  • Cryptography: Fixed Ed25519 PKCS #8 key structure (now compatible with OpenSSL).
  • Cryptography: Optimized memory usage in symmetric encryption transformations based on Windows CNG API.
  • Cryptography: Substantial speed-up of ChaCha20/Poly1305 (used in SSH and TLS). Utilizing AVX2 or Advanced NEON SIMD on .NET 5.0 (if available).
  • Common: Accelerated common byte array operations in .NET 5.0 on devices with AVX2 support.

2020 R5 #

(build 7620 from 2020-11-10)

Support for .NET 5.0!

This release adds a new set of binaries targeting the final version of .NET 5.0. It supports all .NET 5.0 platforms:

  • Windows (x64, x86, ARM64)
  • Linux (x64, ARM32, ARM64)
  • macOS (x64)

Support for Ed25519 X.509 certificates in TLS 1.3

We added support for TLS 1.3 with X.509 certificates using Ed25519 algorithm (EdDSA on edwards25519 curve) to all Rebex components with TLS support.

However, due to limitations of .NET and all supported operating systems, a custom certificate validator is needed to validate Ed25519 certificates.


Our new Rebex.Security.Cryptography.AesGcm class resembles .NET 5.0's class of the same name, but it's available on all supported platforms including .NET Framework 3.5/4.0 and Mono 5/6.

Detailed list of changes:

  • All: Added support for .NET 5.0 on all platforms.
  • TLS Core: Added support for X.509 certificates with Ed25519 keys to TLS 1.3.
  • TLS Core: Improved exception messages in TLS 1.3.
  • Cryptography: Added built-in support for Ed25519 algorithm.
  • Cryptography: Added Rebex.Security.Cryptography.AesGcm class (equivalent to .NET 5.0's AesGcm class, but available on all platforms including .NET Framework 3.5).
  • Cryptography: Added SetOtherNames/GetOtherNames methods to CertificateInfo class ('Other Name' support in SANs).
  • Cryptography: AsymmetricKeyAlgorithm.ImportKey method can initialize Ed25519 key from seed (in addition to private key).
  • Cryptography: AsymmetricKeyAlgorithm.Register method made thread-safe.
  • Cryptography: Deprecated CryptoHelper.ForceManagedAes property.
  • Cryptography: Enhanced compatibility with unsupported legacy versions of CryptoAPI.
  • Cryptography: Enhanced SignedData.Load(Stream) and EnvelopedData.Load(Stream) methods to support Base64-encoded format (PEM) as well.
  • Cryptography: Enhanced workaround for RSA CSPs with lack of SHA-2 support.
  • Common: Added SspiAuthentication.IsSupported method.
  • Common: Enhanced EncodingTools helper class to always provide Encodings with implemented HeaderName, EncodingName and BodyName properties.

2020 R4 #

(build 7579 from 2020-09-30)

Fully tested on .NET 5.0 RC1

Rebex assemblies targeting .NET Standard 2.1 have been fully tested on .NET 5.0 RC1 and are suitable to be used in production on Microsoft's latest .NET platform.

Maintenance release

This is a maintenance release with enhancements in the shared functionality.

Detailed list of changes:

  • All: Fixed several minor compatibility issues on .NET 5.0 RC1.
  • Networking: Restored missing NetworkSession.InstanceId property.
  • TLS Core: Fixed concurrent access in server-side TLS session cache.
  • TLS Core: Fixed normalization of premaster secret in server-side ECDH calculations in TLS 1.2 and earlier.
  • TLS Core: Updated TlsCipherSuite.Secure/Weak/Fast enum values. Updated TlsParameters.AllowedSuite default.
  • TLS: Added more AuthenticateAsClientAsync/AuthenticateAsServerAsync overloads.
  • Cryptography: Added Ed25519 support to Certificate class. (Not yet supported by the built-in certificate validator due to lack of support in Windows and .NET).
  • Cryptography: Fixed handling of non-content data in Certificate(byte[]) constructor and CertificateChain.LoadP7b(Stream) / CertificateRevocationList.Load(Stream) methods.
  • Cryptography: Fixed parsing of constructed primitive ASN.1 types with more than two layers of nesting.
  • Cryptography: Fixed version number in PKCS #10 CertificationRequest structure.
  • Cryptography: Prohibited usage of Chacha20/Poly1305 in TLS 1.3 in FIPS-only mode. (Already prohibited in TLS 1.2 or earlier.)
  • Cryptography: Updated RSAManaged constructor logic to make it suitable as a base for derived classes on .NET Framework in FIPS-compliant mode.
  • Cryptography: Using Windows CNG API for Diffie-Hellman parameter generation on Windows 10 and Windows Server 2016/2019.
  • Common: Optimized internal cancellation infrastructure on old platforms.
  • Common: Removed usage of BinaryFormatter which has been found to be insecure.
  • Common: Updated EncodingTools.GetEncoding method to prefer encodings provided by .NET.

2020 R3 #

(build 7501 from 2020-07-14)

Binaries for .NET Standard 2.1

We added a new set of binaries targeting .NET Standard 2.1. They are suitable for .NET Core 3.1 and .NET 5.0 Preview 6, on Windows, Linux and macOS.

For an overview of available binaries and supported platforms, check out Rebex Support Lifecycle KB article.

New TlsStream API

In addition to TlsClientSocket and TlsServerSocket, Rebex TLS now featues TlsStream class as well. Its API resembles .NET's SslStream, and it supports TLS 1.0-1.3 on all mainstream .NET platforms including .NET Framework 3.5 on Windows 7 (or even on Windows XP SP3 with a plugin).

Improved TLS core

This release brings enhancements, optimizations.

Detailed list of changes:

  • All: Added binaries targeting .NET Standard 2.1.
  • SSH: Enhanced legacy group exchange autodetection.
  • TLS Core: Added TlsSocket.ApplicationProtocol property to make it possible to determine protocol negotiated using ALPN extension.
  • TLS Core: Always preferring RSA/SHA-2 for client certificate authentication in TLS 1.2.
  • TLS Core: Disabled ciphers based on AES/CBC and SHA-2 in legacy versions of TLS (they are only specified by TLS 1.2).
  • TLS Core: Fixed availability of TLS 1.3 session tickets (client side).
  • TLS Core: Fixed handling of multiple concurrent Receive or Send method calls in TLS 1.3.
  • TLS Core: Fixed handling of TLS 1.3 KeyUpdate handshake message.
  • TLS Core: Fixed server name handling for TlsSocket instances created from an already-connected Socket.
  • TLS Core: Fixed TlsException.Status to return ConnectionClosed for connection-closed errors.
  • TLS Core: Fixed TlsException.Status to return Timeout for timeout errors.
  • TLS Core: Fixed TlsSocket.ClientCertificate that returned an empty chain instead of null in some scenarios.
  • TLS Core: Improved error message when server certificate is rejected in TLS 1.3.
  • TLS Core: Improved error messages in TLS 1.3.
  • TLS Core: Logging improvements.
  • TLS Core: No longer sending 'internal error' alert to remote end on timeout.
  • TLS Core: Optimized TLS 1.3 internals.
  • TLS Core: TLS 1.3 initiates key update properly (before the AEAD limits are reached).
  • TLS Core: Unified behavior of the Receive and ReceiveAsync methods across TLS versions.
  • TLS: Added DisposeAsync method to TlsSocket.
  • TLS: Added server-side support for Application-Layer Protocol Negotiation (ALPN) extension (RFC 7301).
  • TLS: Added TlsParameters.CertificateChainMode property.
  • TLS: Added TlsStream class. Supports TLS 1.0-1.3 via Stream-based API.
  • TLS: An error is reported when trying to use one of deprecated methods via TlsServerSocket.
  • TLS: Fixed error messages reported on client certificate validation to properly refer to client certificate.
  • TLS: Fixed error reporting when trying to use SSL 3.0 on Windows OS in FIPS-only mode.
  • Cryptography: Fixed encoding of ECDSA signatures in PKCS #7 CertificationRequest structure.
  • Cryptography: Memory usage optimizations in CNG layer.
  • Cryptography: On Windows 10 and Windows Server 2016 or higher, Windows CNG API is used for classic Diffie-Hellman calculations instead of legacy Windows CryptoAPI.
  • Cryptography: Optimized disposing of temporary keys in Certificate class.

2020 R2 #

(build 7450 from 2020-05-24)

Server-side TLS 1.3 support

Added TlsServerSocket class. Supports server-side TLS 1.3, 1.2, 1.1 and 1.0.

Detailed list of changes:

  • SSH: Added new properties to SshCipher to make it possible to determine IDs of active ciphers.
  • SSH: Added workaround for a weakness in legacy CBC ciphers.
  • TLS Core: Enhanced TlsSocket.Timeout property to apply to subsequent Send, SendAsync, Receive and ReceiveAsync methods even when TLS is already active.
  • TLS Core: Fixed availability of TLS 1.3 session ticket when the receive side of the connection has already been closed.
  • TLS Core: Fixed behavior of server-side DoNotCacheSessions option (which previously led to connection failures).
  • TLS Core: Fixed some cases of missing AggregateException unwrapping.
  • TLS Core: Improved and unified behavior of TlsSocket Shutdown/ShutdownAsync methods when negotiation has not been started.
  • TLS Core: Improved TLS exception reporting.
  • TLS Core: Logging improvements.
  • TLS Core: Optimizations in TLS 1.3 internals.
  • TLS Core: Support for the TLS 1.3 record with empty application data payload and random padding.
  • TLS Core: Unified TlsSocket.Cipher property behavior across TLS versions.
  • TLS: Added TlsServerSocket class. Provides server-side TLS 1.3, 1.2, 1.1 and 1.0 support.
  • TLS: Fixed TlsClientSocket.EndConnect method.
  • Cryptography: Added ContentInfo.ToStream() method.
  • Cryptography: Enhanced Certificate.LoadDerWithKey to support RSASSA-PSS and RSAES-OAEP for RSA keys.
  • Cryptography: Fixed AsymmetricKeyAlgorithm.GenerateDiffieHellmanParameters slowness (only affected the previous release).
  • Cryptography: Improved AsymmetricKeyAlgorithm to support RSASSA-PSS and RSAES-OAEP with keys loaded via ImportKey method.
  • Cryptography: Optimized Certificate and CertificateChain class to only consume native resources when needed.
  • Cryptography: Optimized CNG handles cleanup.

2020 R1.1 #

(build 7390 from 2020-03-25)

Fixed several TlsClientSocket omissions

This version fixes several omissions and leftovers in the new TlsClientSocket class, mostly related to legacy parts of its API that have been retained from the existing TlsSocket class

Detailed list of changes:

  • Networking: Fixed rare race condition in TLS and SSH internals.
  • TLS Core: Fixed breaking changes in the behavior of seldom-used parts of TlsSocket API.
  • TLS Core: Fixed handling of OperationCanceledException in TLS 1.3 core.
  • TLS Core: Improved TLS logging.
  • TLS: Added BeginNegotiate/EndNegotiate methods to TlsClientSocket class.
  • TLS: Added support for TlsClientSocket.Available property.
  • TLS: Fixed disabled BeginConnect/EndConnect on TlsClientSocket.
  • TLS: Fixed TlsClientSocket's BeginSend/BeginReceive methods to use truly asynchronous implementation.
  • Common: Added DiffieHellmanNative class to Rebex.Common.Native assembly (speeds up Diffie-Hellman calculations on Xamarin.Android).

2020 R1 #

(build 7357 from 2020-02-21)

New component: Rebex TLS

Rebex TLS is a low-level TLS client library. It supports TLS 1.3, TLS 1.2 and earlier versions on all mainstream platforms including .NET Framework 3.5 on Windows 7 (or on Windows XP SP3 with a plugin). SHA-2, SNI, AES/GCM, ChaCha20/Poly1305 and other modern TLS features are supported as well.

The new library is available as a standalone package or as a part of Rebex Total Pack.

Detailed list of changes:

  • All: Binaries targeting .NET Standard 2.0 now support Xamarin.Android and Xamarin.iOS.
  • All: Deprecated binaries targeting .NET Standard 1.5, Xamarin.Android and Xamarin.iOS.
  • All: Fixed several occurences of culture-sensitive string formatting.
  • All: Fixed several occurrences of wrong synchronization context.
  • All: Mainstream edition no longer supports .NET Framework 2.0/3.0 and .NET Core 1.0/1.1.
  • SSH: Added full support for Elliptic Curve Diffie-Hellman (ECDH) on Windows 10, Windows Server 2016 and Windows Server 2019.
  • SSH: Added support for 'curve25519-sha256' key exchange cipher (equivalent to already-supported '').
  • SSH: Enhanced performance of ChaCha20-Poly1305 cipher ('') in SSH client.
  • SSH: Fixed possible deadlock in SSH client when processing incoming EOF packet while waiting for remote receive buffer size to increase.
  • TLS Core: Added asynchronous methods to TlsSocket base class.
  • TLS Core: Added SetSymmetricCipherSuites/GetSymmetricCipherSuites methods to configure enabled TLS 1.3 cipher suites.
  • TLS Core: Added support for ChaCha20-Poly1305 cipher suites to TLS 1.3 and 1.2.
  • TLS Core: Fixed behavior of TlsSocket methods after Dispose has been called.
  • TLS Core: Fixed behavior of TlsSocket.Shutdown.
  • TLS Core: Improved argument checks in TlsSocket base class.
  • TLS Core: Improved multi-pass parsing of the TLS 1.3 records.
  • TLS Core: Many optimizations in TLS 1.3 core.
  • TLS: Initial release of a stand-alone Rebex TLS library.
  • Cryptography: Added full support for Elliptic Curve Diffie-Hellman (ECDH) on Windows 10, Windows Server 2016 and Windows Server 2019.
  • Cryptography: Added native support for ECDH with X25519 curve on Windows 10, Windows Server 2016 and Windows Server 2019.
  • Common: Internal optimizations.