签名验证
制品签名允许你验证你手中的制品确实是由项目工作流创建的，并且未被未授权方（如中间人）篡改。验证为所有相关方提供了共同的基础、保障和信心，确保大家所指的确实是同一个制品（无论是可执行文件、SBOM 还是文本文件）。
自 Caddy v2.6.0 起，CI/CD 发布制品使用项目 Sigstore 技术进行签名，该技术会颁发包含证书持有者详细信息的证书。你可以先检查用于签名你所选制品的证书。证书是 base64 编码的，因此你需要先 base64 解码以获得 PEM 文件。本例中，我们以 caddy_2.6.0_checksums.txt 制品为例，假设你在类 Linux 环境下操作。
首先下载与你的制品相关的 3 个文件（即 <the artifact>，即你要验证的实际制品，<the artifact>.sig，即制品的签名文件，以及 <the artifact>.pem，即由 Sigstore 的 Fulcio 颁发的根证书链下的证书）。然后 base64 解码下载的 .pem 文件，得到装甲版证书：
base64 -d < caddy_2.6.0_checksums.txt.pem > cert.pem现在你可以使用 openssl 命令检查证书。运行 openssl x509 -in cert.pem -text，你会看到如下输出片段：
openssl x509 -in cert.pem -text
Certificate:
Data:
Version: 3 (0x2)
Serial Number:
22:b0:45:9d:ad:d7:54:98:67:66:b7:de:31:01:ef:4a:02:ab:fb:60
Signature Algorithm: ecdsa-with-SHA384
Issuer: O=sigstore.dev, CN=sigstore-intermediate
Validity
Not Before: Sep 20 17:17:06 2022 GMT
Not After : Sep 20 17:27:06 2022 GMT
Subject:
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
Public-Key: (256 bit)
pub:
04:22:ee:f6:b1:85:1c:de:cf:90:1d:91:75:36:c4:
82:9d:54:5e:f3:a6:5b:3f:18:89:8a:0b:de:d8:93:
7c:02:40:39:00:d4:4e:19:0b:30:93:cc:a4:d0:df:
35:f7:b1:08:24:89:cf:3a:38:06:ff:92:75:06:84:
b5:9e:25:8c:9a
ASN1 OID: prime256v1
NIST CURVE: P-256
X509v3 extensions:
X509v3 Key Usage: critical
Digital Signature
X509v3 Extended Key Usage:
Code Signing
X509v3 Subject Key Identifier:
3B:C0:D1:D2:C8:BA:2D:55:95:1F:68:78:DC:C6:2C:D9:B5:17:0E:EA
X509v3 Authority Key Identifier:
keyid:DF:D3:E9:CF:56:24:11:96:F9:A8:D8:E9:28:55:A2:C6:2E:18:64:3F
X509v3 Subject Alternative Name: critical
URI:https://github.com/caddyserver/caddy/.github/workflows/release.yml@refs/tags/v2.6.0
1.3.6.1.4.1.57264.1.1:
https://token.actions.githubusercontent.com
1.3.6.1.4.1.57264.1.2:
push
1.3.6.1.4.1.57264.1.3:
821a08a6e39ed0e7c43b0271ccf126c194eb6339
1.3.6.1.4.1.57264.1.4:
Release
1.3.6.1.4.1.57264.1.5:
caddyserver/caddy
1.3.6.1.4.1.57264.1.6:
refs/tags/v2.6.0
1.3.6.1.4.1.11129.2.4.2:
.z.x.v..`..(R.hE..k'..Eg...=.8.m..".6or....[.DS.....G0E.!..>MD.a..B.p..^..P*...um.....X..F. NYy.....#...TWIZ...y..qa....4P..
Signature Algorithm: ecdsa-with-SHA384
30:66:02:31:00:be:b3:3c:15:56:78:64:c6:0f:bc:48:69:a9:
0a:27:cd:4d:92:39:00:50:42:a8:2a:ad:11:4d:64:f2:61:35:
ec:08:e9:b5:6a:14:1b:f6:c1:0e:46:ee:a0:54:08:26:e1:02:
31:00:a7:6d:97:db:4c:c8:dd:47:13:3d:28:7a:a6:f3:64:50:
2c:5a:9d:9d:10:d0:cf:6f:d0:e9:37:76:fd:cc:8e:9d:c3:6b:
ba:78:07:40:6a:40:d6:db:f6:97:d5:6a:36:9d
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
现在我们有了证书，可以用 cosign 命令行工具验证签名。运行如下命令（注意这里用的是未解码的证书）：
COSIGN_EXPERIMENTAL=1 cosign verify-blob --certificate ./caddy_2.6.0_checksums.txt.pem --signature ./caddy_2.6.0_checksums.txt.sig ./caddy_2.6.0_checksums.txt
tlog entry verified with uuid: 04deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09 index: 3618623
Verified OK
我们现在切换命令行工具，使用 rekor-cli，它与存储透明日志的公有 Rekor 服务器交互。运行：
rekor-cli get --uuid 04deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09 --format json | jq -r '.'
jq 用于美化输出。你应该会看到如下输出：
{
"Attestation": "",
"AttestationType": "",
"Body": {
"HashedRekordObj": {
"data": {
"hash": {
"algorithm": "sha256",
"value": "508f1044ecd9f14c43c6c8986b45b90fc79f25736e2bc85c0911433ce82533f2"
}
},
"signature": {
"content": "MEUCIHGL2HP5XzcUESTxIk72FS1aNK54LesTfyo+dVhRMeduAiEAnWZDZ5Ur44Y9056vr4to2Fb9FteG53eAFotv3fUZ4h4=",
"publicKey": {
"content": "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"
}
}
}
},
"LogIndex": 3618623,
"IntegratedTime": 1663694226,
"UUID": "04deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09",
"LogID": "c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d"
}
注意 .Body.HashedRekordObj.signature.content 的值与我们 CI 生成并存储在 caddy_2.6.0_checksums.txt.sig 文件中的签名内容一致。此外，所用证书也存储在 Rekor 服务器中，并可在响应的 .Body.HashedRekordObj.signature.publicKey.content 字段中找到，与我们下载的 caddy_2.6.0_checksums.txt.pem 文件内容一致。你还可以进一步检查 .Body.HashedRekordObj.data.hash.value 是否与命令 sha256sum ./caddy_2.6.0_checksums.txt 的输出一致。这样我们就有了匹配的证书、匹配的签名和匹配的校验和（该校验和是归档文件校验和文件的校验和，不是其自身的校验和；该校验和由 Sigstore 生态系统外部提供并记录）。所有这些都被公开记录在透明日志中，供公众验证。
验证制品的真实性
如果你拿到一个声称是 Caddy 项目产物的制品，但没有获得签名文件或证书怎么办？你可以用 rekor-cli 查询 Rekor 服务器获取该制品的信息：
rekor-cli search --artifact ./caddy_2.6.0_checksums.txt --format json | jq -r '.UUIDs[0]'
Found matching entries (listed by UUID):
362f8ecba72f432604deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09注意 UUID 与前文相同。你可以像前面一样查询该 UUID 的详细信息：
rekor-cli get --uuid 04deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09 --format json | jq -r '.'你也可以用一行命令合并上述两步：
rekor-cli get --uuid $(rekor-cli search --artifact ./caddy_2.6.0_checksums.txt --format json | jq -r '.UUIDs[0]') --format json | jq -r '.'
{
"Attestation": "",
"AttestationType": "",
"Body": {
"HashedRekordObj": {
"data": {
"hash": {
"algorithm": "sha256",
"value": "508f1044ecd9f14c43c6c8986b45b90fc79f25736e2bc85c0911433ce82533f2"
}
},
"signature": {
"content": "MEUCIHGL2HP5XzcUESTxIk72FS1aNK54LesTfyo+dVhRMeduAiEAnWZDZ5Ur44Y9056vr4to2Fb9FteG53eAFotv3fUZ4h4=",
"publicKey": {
"content": "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"
}
}
}
},
"LogIndex": 3618623,
"IntegratedTime": 1663694226,
"UUID": "04deb84e5a73ba75ea69092c6d700eaeb869c29cae3e0cf98dbfef871361ed09",
"LogID": "c0d23d6ad406973f9559f3ba2d1ca01f84147d8ffc5b8445c224f98b9591801d"
}
我们现在知道该制品已签名，且其签名已记录在 Rekor 透明日志服务器上。下一步是验证签名和制品确实是 Caddy 项目 CI/CD 工作流的产物。我们可以从 Rekor 查询得到的 JSON 中提取公钥，base64 解码为 PEM 文件，然后用 openssl 检查证书。运行以下命令从 Rekor 响应中提取证书，base64 解码并保存到文件：
rekor-cli get --uuid $(rekor-cli search --artifact ./caddy_2.6.0_checksums.txt --format json | jq -r '.UUIDs[0]') --format json | jq -r '.Body.HashedRekordObj.signature.publicKey.content' | base64 -d > cert.pem
现在用 openssl 检查证书，关注 X509v3 extensions 部分。
openssl x509 -in cert.pem -text
Certificate:
...
Issuer: O=sigstore.dev, CN=sigstore-intermediate
...
X509v3 extensions:
X509v3 Key Usage: critical
Digital Signature
X509v3 Extended Key Usage:
Code Signing
X509v3 Subject Key Identifier:
3B:C0:D1:D2:C8:BA:2D:55:95:1F:68:78:DC:C6:2C:D9:B5:17:0E:EA
X509v3 Authority Key Identifier:
keyid:DF:D3:E9:CF:56:24:11:96:F9:A8:D8:E9:28:55:A2:C6:2E:18:64:3F
X509v3 Subject Alternative Name: critical
URI:https://github.com/caddyserver/caddy/.github/workflows/release.yml@refs/tags/v2.6.0
1.3.6.1.4.1.57264.1.1:
https://token.actions.githubusercontent.com
1.3.6.1.4.1.57264.1.2:
push
1.3.6.1.4.1.57264.1.3:
821a08a6e39ed0e7c43b0271ccf126c194eb6339
1.3.6.1.4.1.57264.1.4:
Release
1.3.6.1.4.1.57264.1.5:
caddyserver/caddy
1.3.6.1.4.1.57264.1.6:
refs/tags/v2.6.0
1.3.6.1.4.1.11129.2.4.2:
.z.x.v..`..(R.hE..k'..Eg...=.8.m..".6or....[.DS.....G0E.!..>MD.a..B.p..^..P*...um.....X..F. NYy.....#...TWIZ...y..qa....4P..
...
扩展值表明了制品的真实性。各扩展的定义可参考 Sigstore OID 信息。
如果签名未通过验证怎么办？
签名验证失败表明该制品并非由 Caddy 项目在 GitHub 上的 CI/CD 工作流生成。如果你有签名、证书和制品，那么你应该看到 cosign 报告验证成功。或者，你可以用 rekor-cli 检查 Rekor 服务器的条目，验证证书扩展值是否正确，并比对校验和和签名。如果不匹配或 Rekor 没有条目，说明该制品不是 Caddy 项目 CI/CD 生成的，或者在 CI/CD 构建流程、GitHub 发布页和交付给你之间被篡改。