picotls

Picotls is a TLS 1.3 implementation written in C.

At the moment, the library implements Draft 18 of the specification, including support 0-RTT resumption using PSK or PSK-DHE.

Primary goal of the project is to create a fast, tiny TLS 1.3 implementation that can be used with the HTTP/2 protocol stack and possibly the upcoming QUIC stack of the H2O HTTP/2 server.

Picotls only implements the communination protocol; cryptographic operations are delegated to cryptographic engines. At the moment, minicrypto binding (uses cifra and micro-ecc) and openssl binding are provided.

License and algorithms supported by the bindings are as follows:

Binding	License	Key Exchange	Certificate	AEAD cipher
minicrypto	CC0 / 2-clause BSD	secp256r1, x25519	ECDSA (P256)1	AES-128-GCM
OpenSSL	OpenSSL	secp256r1	RSA, ECDSA (P256)	AES-128-GCM

Note 1: Minicrypto binding is capable of signing a handshake using the certificate's key, but cannot verify a signature sent by the peer.

How to

If you have cloned picotls from git then ensure that you have initialised the submodules:

% git submodule init
% git submodule update

Build using cmake:

% cmake .
% make
% make check

Run the test server (at 127.0.0.1:8443):

% ./cli -c /path/to/certificate.pem -k /path/to/private-key.pem  127.0.0.1 8443

Connect to the test server:

% ./cli 127.0.0.1 8443

Using resumption:

% ./cli -s session-file 127.0.0.1 8443

The session-file is read-write. The cli server implements a single-entry session cache. The cli server sends NewSessionTicket when it first sends application data after receiving ClientFinished.

Using early-data:

% ./cli -s session-file -e 127.0.0.1 8443

When -e option is used, client first waits for user input, and then sends CLIENT_HELLO along with the early-data.

License

The software is provided under the MIT license. Note that additional licences apply if you use the minicrypto binding (see above).