今天拿到一個 Java 在用的 JKS 檔案，

不過平常我不會寫 Java，要怎麼確認這個 JKS 檔案的內容呢？

查了一下，假設有安裝 JDK 或 OpenJDK 的話，

那應該會有 keytool 這個工具可以用～

跑下面的指令，就可以列出 JKS 檔案裡面的東西：

$ keytool -list -v -keystore test.jks

Enter keystore password:
Keystore type: JKS
Keystore provider: SUN

Your keystore contains 1 entry

Alias name: ca
Creation date: Oct 9, 2024
Entry type: trustedCertEntry

Owner: CN=Root CA, O=TestCompany, C=US
Issuer: CN=Root CA, O=TestCompany, C=US
Serial number: 256b34495e72af99561ea82ca4128abc
Valid from: Wed Sep 11 21:13:57 CST 2024 until: Sun May 29 21:13:57 CST 2044
Certificate fingerprints:
     SHA1: 5A:79:C7:29:20:41:21:05:5F:71:20:10:4B:89:1B:D3:4B:4A:9A:1A
     SHA256: 80:B3:A8:2B:AE:F8:6F:F0:42:A3:20:5C:DE:1C:EE:91:21:F4:C4:DC:D5:F7:7E:8B:AF:16:A1:90:8F:0C:A3:1F
Signature algorithm name: SHA256withRSA
Subject Public Key Algorithm: 4096-bit RSA key
Version: 3

Extensions:

#1: ObjectId: 2.5.29.19 Criticality=true
BasicConstraints:[
  CA:true
  PathLen: no limit
]

#2: ObjectId: 2.5.29.15 Criticality=true
KeyUsage [
  DigitalSignature
  Key_Encipherment
  Key_CertSign
]

#3: ObjectId: 2.5.29.14 Criticality=false
SubjectKeyIdentifier [
KeyIdentifier [
0000: D2 45 4E DA F1 47 3B 63   B7 4F A0 72 F6 7C BA 53  .EN..G;c.O.r...S
0010: 39 73 21 58                                        9s!X
]
]



*******************************************
*******************************************