查詢簽名信息
參考：The Most Common Java Keytool Keystore Commands
# Java Keytool Commands for Checking
# If you need to check the information within a certificate, or Java
# keystore, use these commands.
# Check a stand-alone certificate
keytool -printcert -v -file mydomain.crt
# Check which certificates are in a Java keystore
keytool -list -v -keystore keystore.jks
# Check a particular keystore entry using an alias
keytool -list -v -keystore keystore.jks -alias mydomain
實際操作分 3 種情況：
- 對于 apk 包，直接使用：
keytool -list -printcert -jarfile app.apk
- 對于解壓/反編譯文件，在
META-INF/下找到一個***.RSA服协，然后使用命令：
keytool -printcert -v -file ***.RSA
- 對于本地的密鑰庫文件
****.keystore，則可直接使用：
keytool -list -v -keystore ****.keystore -alias mydomain -storepass mypassword
