ACME

ACME - Automatic Certificate Management Environment
- 自动证书管理环境
- rfc8555
- wiki ACME
step ca
hakwerk/labca

Provider

letsencrypt
- 频率 50 domain/week, 5 duplicate certificates/week
- K8S cert-manager 配置的时候注意，如果配置的 secret 覆盖，会导致
- 问题排查
  - https://crt.sh/?q=baidu.com
  - https://letsdebug.net/
ZeroSSL
- 不支持 ACME 账号自动申请 - 需要注册账号, 客户端要支持 EAB
- 无频率限制
- Maximum NIST P-384
- 支持 certificate revocation
BuyPass
- 只对 ACME 账号提供 RSA 证书
- 支持自动 ACME account 申请
- Maximum NIST P256 certs
- 支持 certificate revocation
- 默认证书 6 个月 - 对于 ACME 自动化来说并不是特别好
- 20 domain/week, 5 duplicate certificates/week
sslcom
- 需要账号
- 单证书 500 域名
- 域名证书不限
参考
- letsencrypt/boulder
  - ACME CA
- letsencrypt/pebble
  - small RFC 8555 ACME test server
- crt.sh
  - 证书记录查询
- hashicorp/vault#8690 Vault as an ACME-based CA
- acmesh-official/acme.sh/wiki/Server

Provider	wildcard	ACME server URL	Doc
letsencrypt	✅	https://acme-v02.api.letsencrypt.org/directory	https://letsencrypt.org/docs/rate-limits/
letsencrypt_test		https://acme-staging-v02.api.letsencrypt.org/directory
buypass	❌	https://api.buypass.com/acme/directory
buypass_test		https://api.test4.buypass.no/acme/directory
zerossl	✅	https://acme.zerossl.com/v2/DV90	https://zerossl.com/documentation/acme/
sslcom		https://acme.ssl.com/sslcom-dv-rsa, https://acme.ssl.com/sslcom-dv-ecc

HTTP-01
- http://example.com/.well-known/acme-challenge/<challenge>
- 要求 80 能被外部访问
- 一次一个域名
DNS-01
- TXT _acme-challenge.example.com <challenge>
- 要求能修改 DNS
- 支持泛域名证书
TLS-ALPN-01
- 与 HTTP-01 类似
- 使用临时 cert
- 不需要 80 端口，但要求 443 端口能被外部访问
- 适用于 TLS-terminating reverse proxies
TLS-SNI-01
- 废弃