Android 中使用系统签名的方法
Android Build中系统签名使用方法
Key的目录
默认加密key是放在Android源码的/build/target/product/security目录下
其中，.pk8文件为私钥，.x509.pem文件为公钥
platform.x509.pem 、platform.pk8 这两个文件位置其实并不是固定的，在Android 平台可以自定义路径
export PRODUCT_DEFAULT_DEV_CERTIFICATE := vendor/xxxx/security/releasekey
Key的使用
Apk的Android.mk文件中会指定LOCAL_CERTIFICATE
LOCAL_CERTIFICATE := testkey # 普通APK，默认情况下使用
LOCAL_CERTIFICATE := platform # 该APK完成一些系统的核心功能,这种方式编译出来的APK所在进程的UID为system
LOCAL_CERTIFICATE := shared # 该APK是media/download系统中的一环
LOCAL_CERTIFICATE := media # 该APK是media/download系统testkey。
如果不指定，默认使用testkey。
对应的，除了在Android.mk指定上述的值，还需要在APK源码的AndroidManifest.xml文件的manifest节点里面申明权限：
android:sharedUserId="android.uid.system"
android:sharedUserId="android.uid.shared"
android:sharedUserId="android.media"
key的生成
在/build/target/product/security目录下有个README，里面有说怎么制作这些key以及使用问题
For detailed information on key types and image signing, please see:
https://source.android.com/devices/tech/ota/sign_builds.html
The test keys in this directory are used in development only and should
NEVER be used to sign packages in publicly released images (as that would
open a major security hole).
key generation
--------------
The following commands were used to generate the test key pairs:
development/tools/make_key testkey '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/[email protected]'
development/tools/make_key platform '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/[email protected]'
development/tools/make_key shared '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/[email protected]'
development/tools/make_key media '/C=US/ST=California/L=Mountain View/O=Android/OU=Android/CN=Android/[email protected]'
signing using the openssl commandline (for boot/system images)
--------------------------------------------------------------
1\. convert pk8 format key to pem format
% openssl pkcs8 -inform DER -nocrypt -in testkey.pk8 -out testkey.pem
2\. create a signature using the pem format key
% openssl dgst -binary -sha1 -sign testkey.pem FILE > FILE.sig
extracting public keys for embedding
------------------------------------
dumpkey.jar is a Java tool that takes an x.509 certificate in PEM format as
input and prints a C structure to standard output:
$ java -jar out/host/linux-x86/framework/dumpkey.jar build/target/product/security/testkey.x509.pem
{64,0xc926ad21,{1795090719,2141396315,950055447,2581568430,4268923165,1920809988,546586521,3498997798,1776797858,3740060814,1805317999,1429410244,129622599,1422441418,1783893377,1222374759,2563319927,323993566,28517732,609753416,1826472888,215237850,4261642700,4049082591,3228462402,774857746,154822455,2497198897,2758199418,3019015328,2794777644,87251430,2534927978,120774784,571297800,3695899472,2479925187,3811625450,3401832990,2394869647,3267246207,950095497,555058928,414729973,1136544882,3044590084,465547824,4058146728,2731796054,1689838846,3890756939,1048029507,895090649,247140249,178744550,3547885223,3165179243,109881576,3944604415,1044303212,3772373029,2985150306,3737520932,3599964420},{3437017481,3784475129,2800224972,3086222688,251333580,2131931323,512774938,325948880,2657486437,2102694287,3820568226,792812816,1026422502,2053275343,2800889200,3113586810,165549746,4273519969,4065247892,1902789247,772932719,3941848426,3652744109,216871947,3164400649,1942378755,3996765851,1055777370,964047799,629391717,2232744317,3910558992,191868569,2758883837,3682816752,2997714732,2702529250,3570700455,3776873832,3924067546,3555689545,2758825434,1323144535,61311905,1997411085,376844204,213777604,4077323584,9135381,1625809335,2804742137,2952293945,1117190829,4237312782,1825108855,3013147971,1111251351,2568837572,1684324211,2520978805,367251975,810756730,2353784344,1175080310}}
This is called by build/make/core/Makefile to incorporate the OTA signing keys
into the recovery image.
APK开发环境中系统签名使用方法
AndroidManifest.xml中的android:sharedUserId="android.uid.system"，代表的意思是和系统相同的uid，可以拥有修改系统时间，文件操作等权限。
使用命令行方式
java -jar signapk.jar platform.x509.pem platform.pk8 MyDemo.apk MyDemo_signed.apk
platform.x509.pem
文件位置：platform/build/target/product/security/
platform.pk8
文件位置：platform/build/target/product/security/
signapk.jar
由源文件 /platform/build/tools/signapk/编译产生
生成目录 /out/host/linux-x86/framework/ 中找到
Android Studio方式
build.gradle中添加
signingConfigs {
release {
//发布正式版本模式下的使用的签名文件
keyAliard 'android'
keyPassword 'android'
storeFile file('./platform.keystore')
storePassword 'android'
}
}
关于 platform.keystore 生成有提供如下两种方法
Linux 环境 keystore 生成
platform.pk8、platform.x509.pem转成keystore类型的签名文件
1、环境：Ubuntu
2、JDK配置
3、下载keytool-importkeypair GitHub - getfatday/keytool-importkeypair: A shell script to import key/certificate pairs into an existing Java keystore
4、生成keystore签名文件
将platform.pk8、platform.x509.pem和keytool-importkeypair放到同一个文件夹下，然后打开终端，执行以下语句即可在文件夹下生成keystore签名文件
./keytool -importkeypair -k name.keystore -p android -pk8 platform.pk8 \
-cert platform.x509.pem -alias android
-k：生成的签名文件名称
-p：签名文件密码
-alias：签名文件别名
Note：Android
Windows环境keystore 生成
1、安装OpenSSL，参考 Windows 下OpenSSL安装过程及错误解决办法_离水的鱼儿的博客-CSDN博客_openssl
2、将platform.pk8，platform.x509.pem 文件复制到openSSL安装目录，方便后面执行命令
3、执行文件目录中的start.bat，会打开命令窗
4、在本目录下生成platform.pem文件，目录图中的platform.pem文件此步骤后生成
openssl pkcs8 -inform DER -nocrypt -in platform.pk8 -out platform.pem
5、在本目录下生成platform.p12文件，并设置别名和密码
openssl pkcs12 -export -in platform.x509.pem -out platform.p12 \
-inkey platform.pem -password pass:android -name android
这里设置的别名和密码就是在Android Studio打包时选择的别名和密码（这里都设置为android），输出 platform.p12文件
6.在本目录下生成platform.jks文件
keytool -importkeystore -deststorepass android -destkeystore ./platform.jks \
-srckeystore ./platform.p12 -srcstoretype PKCS12 -srcstorepass android
更多原理性介绍可以看这两篇文档
Android v1、v2、v3签名原理
android-security_介绍