X.509 证书解码器
粘贴 PEM 格式的证书、整条证书链，或以 base64/十六进制表示的 DER。所有内容都在本地解析：身份信息、有效期、密钥与签名算法、扩展和指纹，并附有通俗易懂的算法安全状况说明。
100% 本地运行——所有操作都在你的浏览器中完成，不会向任何服务器发送数据
How it works
Your certificate never leaves this page. The input is split into PEM blocks (or decoded from base64/hex DER), and each block is parsed with an ASN.1 parser compiled into the page itself — subject, validity, key parameters and extensions are read directly from the DER structure. The SHA-256 fingerprint is computed in JavaScript in your browser as well, so no bytes are uploaded anywhere. Assessment notes are rule-based: signature hashes are checked against what modern clients accept, key algorithms against the NIST IR 8547 post-quantum timeline, and lifetimes against the CA/Browser Forum schedule.