Deprecated:

This can only work with OpenSSL 1.1.1-dev(TLS 1.3 draft 18 or 19).

The same feature can be implemented by the configuration command Options:+PrioritizeChacha on later version. (from 1.1.1-pre1 on)

This feature can be backported to OpenSSL 1.1.0 by applying https://github.com/Hardrain980/openssl-1.1.0-patch

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CHACHA20-POLY1305 preference patch for OpenSSL 1.1.1-dev

The original version of patch is from CloudFlare, at https://github.com/cloudflare/sslconfig

With this patch, OpenSSL 1.1.1-dev can now prefer to use CHACHA20-POLY1305 ciphers(including TLS13-CHACHA20-POLY1305 for TLS 1.3) on devices without AES instruction sets.

How to use:

1. use git clone or any downloading tool to have s3_lib.c cloned to your system
2. backup and delete {$OPENSSL_1.1.1_PATH}/ssl/s3_lic.c
3. copy s3_lib.c in this repository to {$OPENSSL_1.1.1_PATH}/ssl/
4. compile and install
5. *.recompile your application depends on OpenSSL if it's linked to OpenSSL statically(NOT shared)