# Let's Encrypt の RSA 4096 ビットを ECC 256 ビットに置き換える方法 **URL:** \ **Category:** Support\ **Created:** [2018 年 8 月 4 日午前 6:17 UTC](https://meta.discourse.org/t/how-to-replace-lets-encrypt-rsa-4096-bits-with-ecc-256-bits/93901 "2018-08-04T06:17:34Z")\ **Posts on this page:** 1\ **Showing post:** 13
**Author:** ![Falco](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/falco/32/179432_2.png) [@Falco](https://meta.discourse.org/u/Falco)\ **Post date:** [2021 年 3 月 11 日午前 1:59 UTC](https://meta.discourse.org/t/how-to-replace-lets-encrypt-rsa-4096-bits-with-ecc-256-bits/93901/13 "2021-03-11T01:59:58Z")
@gerhard が 2019 年に実装しました > > > \[Mozilla\](https://wiki.mozilla.org/Security/Server\_Side\_TLS) recommends ECDSA (P…-256) as certificate type for intermediate compatibility. > > \> ECDSA certificates are recommended over RSA certificates, as they allow the use of ECDHE with Windows 7 clients using Internet Explorer 11 > > Most modern browsers will use cipher suites with the ECDSA certificate. Older browsers will select the RSA certificate and a RSA cipher suite. > > It will create two Let's Encrypt certificates: > \* EC 256 bits (SHA256withRSA) > \* RSA 4096 bits (SHA256withRSA) > > Without this change all the ECDSA cipher suites defined in https://github.com/discourse/discourse\_docker/blob/12f501764f57c827e497eb6fb88e98f8c3c468e6/templates/web.ssl.template.yml#L22 won't work. With the new certificate all cipher suites will work and browsers like IE11 on Windows 7 and Windows 8 will work too. > > \*\*Before:\*\* > !\[\](https://user-images.githubusercontent.com/473736/64466317-a8e8f780-d111-11e9-84f1-f7b1dc75e523.png) > > \*\*After:\*\* > !\[\](https://user-images.githubusercontent.com/473736/64466321-ad151500-d111-11e9-92bf-7c50ef2cd6b1.png) --- _[View the full topic](https://meta.discourse.org/t/how-to-replace-lets-encrypt-rsa-4096-bits-with-ecc-256-bits/93901)._