近日有群友报告 AlphaSSL 新签的证书兼容性不佳，在用自动证书工具补齐证书链之后仍然无效。鉴于 GlobalSign 近几年搞了一大堆 intermediate CA，估摸着这回终于到 AlphaSSL 头上了。简单查了下，果然。

2022 年底的 AlphaSSL CA - SHA256 - G2 失效，GlobalSign 给了 AlphaSSL CA - SHA256 - G4 作为新的 intermediate CA 证书，写在里面的 AIA 指向 GlobalSign Root CA (01SEP1998 - 28JAN2028, root-r1)。

奇怪的是 2024 年 1 月 28 日之后的 AlphaSSL CA - SHA256 - G4 不再签发证书，改由 GlobalSign GCC R6 AlphaSSL CA 2023 签发原有通道的 AlphaSSL 证书，而后者的 AIA 指向 GlobalSign Root CA - R6 (10DEC2014 - 10DEC2034, root-r6)，且为信任锚。

显然 2024 年 1 月 28 日之后的 AlphaSSL 默认的证书链的信任锚为 2014 年的这张 GlobalSign Root CA - R6。众所周知，一个新信任锚被绝大多数操作系统和软件所接受的周期是极长的，2010 年出的新根证书 (e.g. USERTrust) 依然在很多嵌入式设备、操作系统和浏览器中不受支持。保险起见，新的根证书会找老根证书交叉签名以保证自身的良好的兼容性，GlobalSign 也不例外。因此，重建证书链，将信任锚指向为其交叉签名的较老的根证书上即可解决问题。

查询 https://crt.sh/?caid=272222 得知 GlobalSign GCC R6 AlphaSSL CA 2023 仅有一条直接上级 CA，即 GlobalSign Root CA - R6 (https://crt.sh/?caid=18459)。

继续向上查询，得知 GlobalSign Root CA - R6 除了为信任锚外，还与 GlobalSign Root CA (01SEP1998 - 28JAN2028, root-r1) 有背书，那么解决方案呼之欲出————拼接 GlobalSign GCC R6 AlphaSSL CA 2023, GlobalSign Root CA - R6 和 GlobalSign Root CA 即可解决问题。

将以下代码块附加在叶子证书（第一个 BEGIN CERTIFICATE 起到第一个 END CERTIFICATE 止）后作为证书链：

-----BEGIN CERTIFICATE-----
MIIFjDCCA3SgAwIBAgIQfx8skC6D0OO2+zvuR4tegDANBgkqhkiG9w0BAQsFADBM
MSAwHgYDVQQLExdHbG9iYWxTaWduIFJvb3QgQ0EgLSBSNjETMBEGA1UEChMKR2xv
YmFsU2lnbjETMBEGA1UEAxMKR2xvYmFsU2lnbjAeFw0yMzA3MTkwMzQzMjVaFw0y
NjA3MTkwMDAwMDBaMFUxCzAJBgNVBAYTAkJFMRkwFwYDVQQKExBHbG9iYWxTaWdu
IG52LXNhMSswKQYDVQQDEyJHbG9iYWxTaWduIEdDQyBSNiBBbHBoYVNTTCBDQSAy
MDIzMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA00Jvk5ADppO0rgDn
j1M14XIb032Aas409JJFAb8cUjipFOth7ySLdaWLe3s63oSs5x3eWwzTpX4BFkzZ
bxT1eoJSHfT2M0wZ5QOPcCIjsr+YB8TAvV2yJSyq+emRrN/FtgCSTaWXSJ5jipW8
SJ/VAuXPMzuAP2yYpuPcjjQ5GyrssDXgu+FhtYxqyFP7BSvx9jQhh5QV5zhLycua
n8n+J0Uw09WRQK6JGQ5HzDZQinkNel+fZZNRG1gE9Qeh+tHBplrkalB1g85qJkPO
J7SoEvKsmDkajggk/sSq7NPyzFaa/VBGZiRRG+FkxCBniGD5618PQ4trcwHyMojS
FObOHQIDAQABo4IBXzCCAVswDgYDVR0PAQH/BAQDAgGGMB0GA1UdJQQWMBQGCCsG
AQUFBwMBBggrBgEFBQcDAjASBgNVHRMBAf8ECDAGAQH/AgEAMB0GA1UdDgQWBBS9
BbfzipM8c8t5+g+FEqF3lhiRdDAfBgNVHSMEGDAWgBSubAWjkxPioufi1xzWx/B/
yGdToDB7BggrBgEFBQcBAQRvMG0wLgYIKwYBBQUHMAGGImh0dHA6Ly9vY3NwMi5n
bG9iYWxzaWduLmNvbS9yb290cjYwOwYIKwYBBQUHMAKGL2h0dHA6Ly9zZWN1cmUu
Z2xvYmFsc2lnbi5jb20vY2FjZXJ0L3Jvb3QtcjYuY3J0MDYGA1UdHwQvMC0wK6Ap
oCeGJWh0dHA6Ly9jcmwuZ2xvYmFsc2lnbi5jb20vcm9vdC1yNi5jcmwwIQYDVR0g
BBowGDAIBgZngQwBAgEwDAYKKwYBBAGgMgoBAzANBgkqhkiG9w0BAQsFAAOCAgEA
fMkkMo5g4mn1ft4d4xR2kHzYpDukhC1XYPwfSZN3A9nEBadjdKZMH7iuS1vF8uSc
g26/30DRPen2fFRsr662ECyUCR4OfeiiGNdoQvcesM9Xpew3HLQP4qHg+s774hNL
vGRD4aKSKwFqLMrcqCw6tEAfX99tFWsD4jzbC6k8tjSLzEl0fTUlfkJaWpvLVkpg
9et8tD8d51bymCg5J6J6wcXpmsSGnksBobac1+nXmgB7jQC9edU8Z41FFo87BV3k
CtrWWsdkQavObMsXUPl/AO8y/jOuAWz0wyvPnKom+o6W4vKDY6/6XPypNdebOJ6m
jyaILp0quoQvhjx87BzENh5s57AIOyIGpS0sDEChVDPzLEfRsH2FJ8/W5woF0nvs
BTqfYSCqblQbHeDDtCj7Mlf8JfqaMuqcbE4rMSyfeHyCdZQwnc/r9ujnth691AJh
xyYeCM04metJIe7cB6d4dFm+Pd5ervY4x32r0uQ1Q0spy1VjNqUJjussYuXNyMmF
HSuLQQ6PrePmH5lcSMQpYKzPoD/RiNVD/PK0O3vuO5vh3o7oKb1FfzoanDsFFTrw
0aLOdRW/tmLPWVNVlAb8ad+B80YJsL4HXYnQG8wYAFb8LhwSDyT9v+C1C1lcIHE7
nE0AAp9JSHxDYsma9pi4g0Phg3BgOm2euTRzw7R0SzU=
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

即可完成证书链建构。