They generally do open source their crypto systems (at least the algorithms themselves), given that that is practically a requirement for any crypto system to be adopted in a widespread way (no one who is serious about security is going to use home-baked closed-source cryptosystems).

Examples: https://en.wikipedia.org/wiki/Speck_(cipher) and https://en.wikipedia.org/wiki/Simon_%28cipher%29 and https://en.wikipedia.org/wiki/GOST_(block_cipher)