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So What Is XChaCha20?

So what’s the encryption that is being used to secure this article? Well, that’s easy, we can just connect to medium.com with OpenSSL:

% openssl s_client  -connect medium.com:443  
CONNECTED(00000005)
depth=2 C = IE, O = Baltimore, OU = CyberTrust, CN = Baltimore CyberTrust Root
verify return:1
depth=1 C = US, O = "Cloudflare, Inc.", CN = Cloudflare Inc ECC CA-3
verify return:1
depth=0 C = US, ST = California, L = San Francisco, O = "Cloudflare, Inc.", CN = medium.com
verify return:1
---
Certificate chain
 0 s:C = US, ST = California, L = San Francisco, O = "Cloudflare, Inc.", CN = medium.com
   i:C = US, O = "Cloudflare, Inc.", CN = Cloudflare Inc ECC CA-3
 1 s:C = US, O = "Cloudflare, Inc.", CN = Cloudflare Inc ECC CA-3
   i:C = IE, O = Baltimore, OU = CyberTrust, CN = Baltimore CyberTrust Root
---
Server certificate
-----BEGIN CERTIFICATE-----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…