) Read signature information

import sun.security.pkcs.PKCS7;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.security.GeneralSecurityException;import java.security.cert.X509Certificate;class SignApk {        public static X509Certificate readSignatureBlock(InputStream in)                        throws IOException, GeneralSecurityException {                PKCS7 pkcs7 = new PKCS7(in);                return pkcs7.getCertificates()[0];        }        public static void main(String[] args) throws FileNotFoundException,                        IOException, GeneralSecurityException {                X509Certificate publicKey = readSignatureBlock(new FileInputStream(                                "D:\cert.rsa"));                System.out.println("issuer:" + publicKey.getIssuerDN());                System.out.println("subject:" + publicKey.getSubjectDN());                System.out.println(publicKey.getPublicKey());        }}

The output content is as follows:

Issuer: Cn = Zhang ZM
Subject: Cn = Zhang ZM
Sun RSA public keys, 1024 bits
Modulus: 1543085941444687053482947604843962642184531 ......

Certificate ------------------------------------------------------------------------------------------------------------------------------------------------

Android signature and Public Key acquisition methods

Private byte [] getsign (context) {packagemanager PM = context. getpackagemanager (); List <packageinfo> apps = PM. getinstalledpackages (packagemanager. get_signatures); iterator <packageinfo> iter = apps. iterator (); While (ITER. hasnext () {packageinfo info = ITER. next (); string packagename = info. packagename; // obtain the signature by package name if (packagename. equals ("com. test. test ") {return info. signatures [0]. tobytearray ();}

　　}    return null;}

 

public static String getPublicKey(byte[] signature) {        try {            CertificateFactory certFactory = CertificateFactory                    .getInstance("X.509");            X509Certificate cert = (X509Certificate) certFactory                    .generateCertificate(new ByteArrayInputStream(signature));            String publickey = cert.getPublicKey().toString();            publickey = publickey.substring(publickey.indexOf("modulus: ") + 9,                    publickey.indexOf("\n", publickey.indexOf("modulus:")));            Log.d("TRACK", publickey);            return publickey;        } catch (CertificateException e) {            e.printStackTrace();        }        return null;}