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