## Release history:

* 0.20.0 (2021-09-26)
  - *Breaking change*: `Connection` is now an enum instead of a trait. You can abstract over
    `ClientConnection` and `ServerConnection` with a bound like `where C: Deref<ConnectionCommon<SD>>, SD: SideData`.
  - *Breaking change*: the SNI arguments to `ClientCertVerifier` methods have been removed.
    The `Acceptor` API now allows selecting a `ServerConfig` based on the `ClientHello` instead.
  - Unclean TCP closure is now tracked by the library.  This means a new error is possible when reading plaintext:
    `ErrorKind::UnexpectedEof` will be returned in this case.
  - *Breaking change*: insulate the rustls public API from webpki API changes:
    - PKI errors are now reported using rustls-specific errors.
    - There is now a rustls-specific root trust anchor type.
  - *Breaking change*: the following types are no longer exposed in the crate root, and can instead be imported
    through the `client` module exposed in the crate root: `ResolvesClientCert`, `StoresClientSessions`,
    `WriteEarlyData`, `ClientSessionMemoryCache`, `NoClientSessionStorage`, `HandshakeSignatureValid`,
    `ServerCertVerified`, `ServerCertVerifier`, `WebPkiVerifier` and `DangerousClientConfig`.
  - *Breaking change*: the following types are no longer exposed in the crate root, and can instead be imported
    through the `server` module exposed in the crate root: `AllowAnonymousOrAuthenticatedClient`,
    `AllowAnyAuthenticatedClient`, `NoClientAuth`, `ResolvesServerCertUsingSni`, `NoServerSessionStorage`,
    `ServerSessionMemoryCache`, `StoresServerSessions`, `ClientHello`, `ProducesTickets`, `ResolvesServerCert`,
    `ClientCertVerified` and `ClientCertVerifier`.
  - *Breaking API change*: `QuicExt::write_hs()` now returns a `KeyChange` type that returns handshake or 1-RTT keys. In the case of 1-RTT keys, a `KeyChange` also
    includes a `Secrets` type that must be used to derive further key updates, independent from the rustls `Connection`. The `QuicExt::next_1rtt_keys()` method
    has been removed.
  - *Breaking API change*: QUIC header protection keys now use a new type that directly exposes a masking/unmasking operation.
* 0.20.0-beta2 (2021-07-04)
  - *Breaking change*: internal buffers are now limited to 64 kB by default. Use
    `Connection::set_buffer_limit` to change the buffer limits to suit your application.
  - *Breaking API change*: PEM parsing now lives in the [rustls-pemfile crate](https://crates.io/crates/rustls-pemfile).
    This means `rustls::internals::pemfile` and `rustls::RootCertStore::add_pem_file` no longer exist.
  - *Breaking API change*: `ServerCertVerifier::verify_server_cert` and `ClientCertVerifier::verify_client_cert`
    pass the end-entity and intermediate certificates separately.  This means rustls deals with the case
    where the certificate chain is empty, rather than leaving that to ServerCertVerifier/ClientCertVerifier
    implementation.
  - *Breaking API change*: `SupportedCipherSuite` is now an enum with TLS 1.2 and TLS 1.3 variants. Some of its
    methods have moved to the inner `Tls12CipherSuite` and `Tls13CipherSuite` types. Instead of
    `usable_for_version()`, it now has a `version()` method. `get_hash()` has been renamed
    to `hash_algorithm()` and `usable_for_sigalg()` to `usable_for_signature_algorithm()`.
  - There are now 80% fewer unreachable unwraps in the core crate thanks to large refactoring efforts.
  - *Breaking API change*: the `WebPkiError` variant of `rustls::Error` now includes which operation failed.
  - *Breaking API changes*: These public API items have been renamed to meet naming guidelines:
    - `rustls::TLSError` to `rustls::Error`.
    - `rustls::ResolvesServerCertUsingSNI` to `rustls::ResolvesServerCertUsingSni`.
    - `rustls::WebPKIVerifier` to `rustls::WebPkiVerifier`.
    - `rustls::ciphersuites` to `rustls::cipher_suites`.
    - `rustls::ALL_CIPHERSUITES` to `ALL_CIPHER_SUITES`; `rustls::DEFAULT_CIPHERSUITES` to `DEFAULT_CIPHER_SUITES`.
    - `rustls::ClientHello::sigschemes` to `rustls::ClientHello::signature_schemes`.
    - `rustls::RootCertStore::get_subjects` to `rustls::RootCertStore::subjects`.
    - `rustls::ServerSession` to `rustls::ServerConnection`.
    - `rustls::ClientSession` to `rustls::ClientConnection`.
    - `rustls::ServerSession::get_sni_hostname` to `rustls::ServerConnection::sni_hostname`.
    - `rustls::ClientConfig::ciphersuites` to `rustls::ClientConfig::cipher_suites`.
    - `rustls::ServerConfig::ciphersuites` to `rustls::ServerConfig::cipher_suites`.
    - `rustls::ProducesTickets::get_lifetime` to `rustls::ProducesTickets::lifetime`.
    - `rustls::Session`: `get_peer_certificates` to `peer_certificates`, `get_alpn_protocol` to `alpn_protocol`,
      `get_protocol_version` to `protocol_version`, `get_negotiated_ciphersuite` to `negotiated_cipher_suite`.
  - *Breaking API change*: `ResolvesServerCert::resolve` and `ResolvesClientCert::resolve` now return
    `Option<Arc<CertifiedKey>>` instead of `Option<CertifiedKey>`.  `CertifiedKey` is now an immutable
    type.
  - *Breaking API change*: `peer_certificates` returns a borrow rather than a copy on the
    internally stored certificate chain.
  - *Breaking API change*: `ClientConnection`'s DNS name parameter is now a new enum, `ServerName`, to allow future support for ECH and servers named by IP address.
* 0.19.1 (2021-04-17):
  - Backport: fix security issue: there was a reachable panic in servers if a client
    sent an invalid `ClientECDiffieHellmanPublic` encoding, due to an errant `unwrap()`
    when parsing the encoding.
* 0.19.0 (2020-11-22):
  - Ensured that `get_peer_certificates` is both better documented, and works
    uniformly for both full-handshake and resumed sessions.
  - Fix bug: fully qualified hostnames should have had their trailing dot
    stripped when quoted in the SNI extension.
* 0.18.1 (2020-08-16):
  - Fix DoS vulnerability in TLS1.3 "Middlebox Compatibility Mode" CCS handling.
    This is thought to be quite minor -- see
    [this commit message](https://github.com/rustls/rustls/commit/e51bf92afcd9dfbd5f4e8154b847aa5cc380913c)
    for a full discussion.
* 0.18.0 (2020-07-04):
  - Allow custom certificate validation implementations to also
    handle handshake signature computation.  This allows uses in non-web
    contexts, where `webpki` is not likely to process the certificates
    in use.  Thanks to @DemiMarie-parity.
  - Performance improvements.  Thanks to @nviennot.
  - Fixed client authentication being unduly rejected by client when server
    uses the superseded certificate_types field of CertificateRequest.
  - *Breaking API change*: The writev_tls API has been removed, in favour
    of using vectored IO support now offered by std::io::Write.
  - Added ed25519 support for authentication; thanks to @potatosalad.
  - Support removal of unused ciphersuites at link-time.  To use this,
    call `ClientConfig::with_ciphersuites` instead of `ClientConfig::new`.
* 0.17.0 (2020-02-22):
  - *Breaking API change*: ALPN protocols offered by the client are passed
    to the server certificate resolution trait (`ResolvesServerCert`).
  - *Breaking API change*: The server certificate resolution trait now
    takes a struct containing its arguments, so new data can be passed
    to these functions without further breaking changes.
  - Signature schemes offered by the client are now filtered to those
    compatible with the client-offered ciphersuites.  Prior to this change
    it was likely that server key type switching would not work for clients
    that offer signature schemes mismatched with their ciphersuites.
  - Add manual with goal-oriented documentation, and rationale for design
    decisions.
  - *Breaking API change*: `AlwaysResolvesClientCert::new` is now fallible,
    as is `ClientConfig::set_single_client_cert`.
* 0.16.0 (2019-08-10):
  - Optimisation of read path for polled non-blocking IO.
  - Correct an omission in TLS1.3 middlebox compatibility mode, causing
    handshake failures with servers behind buggy middleboxes.
  - Move to *ring* 0.16.
  - Assorted refactoring to reduce memory usage during and after
    handshake.
  - Update other dependencies.
* 0.15.2 (2019-04-02):
  - Moved example code around for benefit of Fuchsia.
  - Example code fixes for Windows -- Windows is now a tested platform.
  - QUIC-specific bug fixes.
  - Update dependencies.
* 0.15.1 (2019-01-29):
  - Fix incorrect offering of SHA1.
* 0.15.0 (2019-01-20):
  - Update dependencies.
  - *Breaking API change*: ALPN protocols are now encoded as a `Vec<u8>`, not
    a `String`.  This alters the type of:
    - `ClientConfig::alpn_protocols`
    - `ClientConfig::set_protocols`
    - `ServerConfig::alpn_protocols`
    - `ServerConfig::set_protocols`
    - `Session::get_alpn_protocol`
  - Emit a warning when receiving an invalid SNI extension, such as one
    including an IP address.
  - Extended QUIC support for later QUIC drafts.
  - Correct bug where we'd send more than one fatal alert for
    handshake failure cases.
  - Discontinue support for SHA1 signatures.
  - Move to Rust 2018 edition.
* 0.14.0 (2018-09-30):
  - Introduce client-side support for 0-RTT data in TLS1.3.
  - Fix a bug in rustls::Stream for non-blocking transports.
  - Move TLS1.3 support from draft 23 to final RFC8446 version.
  - Don't offer (e.g.) TLS1.3 if no TLS1.3 suites are configured.
  - Support stateful resumption in TLS1.3.  Stateless resumption
    was previously supported, but is not the default configuration.
  - *Breaking API change*: `generate()` removed from `StoresServerSessions` trait.
  - *Breaking API change*: `take()` added to `StoresServerSessions` trait.
* 0.13.1 (2018-08-17):
  - Fix a bug in rustls::Stream for non-blocking transports
    (backport).
* 0.13.0 (2018-07-15):
  - Move TLS1.3 support from draft 22 to 23.
  - Add support for `SSLKEYLOGFILE`; not enabled by default.
  - Add support for basic usage in QUIC.
  - `ServerConfig::set_single_cert` and company now report errors.
  - Add support for vectored IO: `writev_tls` can now be used to
    optimise system call usage.
  - Support ECDSA signing for server and client authentication.
  - Add type like `rustls::Stream` which owns its underlying TCP stream
    and rustls session.
* 0.12.0 (2018-01-06):
  - New API for learning negotiated cipher suite.
  - Move TLS1.3 support from draft 18 to 22.
  - Allow server-side MTU configuration.
  - Tested against latest BoringSSL test suite.
  - Support RFC5705 exporters.
  - Provide `ResolvesServerCertUsingSNI` for doing SNI-based
    certificate switching.
  - Allow disabling SNI extension on clients, for use with
    custom server certificate verifiers where the hostname
    may not make sense.
  - DNS names are now typesafe, using `webpki::DNSName`.
  - Update dependencies.
* 0.11.0 (2017-08-28):
  - New server API for learning requested SNI name.
  - Server now checks selected certificate for validity.
  - Remove time crate dependency.
  - Follow webpki interface changes.
  - Update dependencies.
* 0.10.0 (2017-08-12):
  - Request and verify SCTs using sct crate.  This doesn't happen
    unless you pass in some certificate transparency logs -- example code
    does this.
  - Request OCSP stapled response and pass to cert verifier.
    Note that OCSP verification is not implemented, but this is the public
    API public change required to support this.
  - Allow OCSP and SCT stapling for servers.
  - Refactor handshake state machines.
  - Bind verifications to final state -- note API change for custom cert
    verification.
* 0.9.0 (2017-06-16):
  - Update dependencies.
  - Add IO helper function (`complete_io`) to `rustls::Session`.
  - Add blocking stream type -- `rustls::Stream` -- to ease use on top
    of blocking sockets.
* 0.8.0 (2017-05-14):
  - Add `dangerous_configuration` feature for unsafe features.
* 0.7.0 (2017-05-08):
  - Update dependencies.
* 0.6.0 (2017-05-06):
  - Update dependencies.
  - Expose ring's new support for PKCS#8-format private keys.
  - New API for applying limitation to internal buffer sizes.
* 0.5.8 (2017-03-16):
  - Fix build on later rustc.
* 0.5.7 (2017-02-27):
  - No changes from 0.5.6; republished with nightly cargo for category support.
* 0.5.6 (2017-02-19):
  - RFC7627 extended master secret support
  - Assorted documentation improvements
* 0.5.5 (2017-02-03):
  - Crate categories.
  - Protocol errors now permanent for given session.
  - Exposed `ResolvesServerCert` trait for customising certification
    selection.
  - Exposed `SignatureScheme` enum.
* 0.5.4 (2017-01-26):
  - First release with TLS1.3-draft-18 support.
  - More performance improvements (now ~15Gbps per core).
  - New API to learn version of negotiated connection.
* 0.5.0 (2016-09-27):
  - Tickets.
  - Coverage testing.
  - Benchmarking.
  - Massive performance improvements (from ~1Gbps to ~6Gbps per core).
  - OSX support.
  - Minor API corrections and additional testing.