Features

Introduced a new assembly which enables token signing and encryption operations via Azure Key Vault. This assembly enables authentication via Managed Service Identity, which means users don’t need to store secrets in the source code or any associated configuration files.
Added .NET 4.6.1 and .NET Standard 2.0 targets.
All asymmetric cryptography target specific logic is now abstracted into AsymmetricWrapper.
Added JWE support to Microsoft.IdentityModel.JsonWebTokens.JsonWebTokenHandler.
Added a new abstract TokenHandler class that contains properties shared across all token handlers.
Added support for JWEs containing a 'zip' (compression algorithm) header parameter to the JsonWebTokenHandler.
Added a Property Bag to ease addition of custom TokenValidationParameters.
Added in a X509EncryptingCredentials class to allow constructing EncryptingCredentials based on a X509 certificate, key wrap algorithm, and data encryption algorithm.
See here for a full list of issues that were fixed.

Breaking Changes

Removed any public references to JObject from Microsoft.IdentityModel.JsonWebTokens in order to distance the library from external dependencies.