Improve readability of singer info

In the What's New dialog, display the subject line along with the first four
characters of SHA-256. In the Main page, display signer info in a more readable
format.

Signed-off-by: Muntashir Al-Islam <muntashirakon@riseup.net>

Author: MuntashirAkon

app/src/main/java/io/github/muntashirakon/AppManager/apk/signing/CertUtils.java

@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package io.github.muntashirakon.AppManager.apk.signing;
+
+import org.bouncycastle.asn1.x500.X500Name;
+import org.bouncycastle.asn1.x500.style.BCStyle;
+
+import java.security.cert.X509Certificate;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public final class CertUtils {
+    public static String getReadableSubject(X509Certificate cert) {
+        return Stream.of(BCStyle.CN, BCStyle.O, BCStyle.L, BCStyle.ST, BCStyle.C)
+                .map(oid -> X500Name.getInstance(cert.getSubjectX500Principal().getEncoded()).getRDNs(oid))
+                .filter(rdns -> rdns.length > 0)
+                .map(rdns -> rdns[0].getFirst().getValue().toString())
+                .collect(Collectors.joining(", "));
+    }
+
+    public static String getReadableSubject(String subjectLine) {
+        Map<String, String> rdnMap = new HashMap<>();
+        Matcher matcher = Pattern.compile("([^=,]+)=(((?<=\\\\),|[^,])+)").matcher(subjectLine);
+        while (matcher.find()) {
+            String key = matcher.group(1).trim().toUpperCase();
+            String value = matcher.group(2).trim().replaceAll("\\\\,", ",");
+            rdnMap.put(key, value);
+        }
+
+        return Stream.of("CN", "O", "L", "ST", "C")
+                .map(rdnMap::get)
+                .filter(value -> value != null && !value.isEmpty())
+                .collect(Collectors.joining(", "));
+    }
+}

app/src/main/java/io/github/muntashirakon/AppManager/apk/whatsnew/ApkWhatsNewFinder.java

@@ -12,11 +12,14 @@
 
 import androidx.annotation.IntDef;
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
 import androidx.core.content.pm.PackageInfoCompat;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -25,9 +28,12 @@
 import java.util.Set;
 
 import io.github.muntashirakon.AppManager.R;
+import io.github.muntashirakon.AppManager.apk.signing.CertUtils;
+import io.github.muntashirakon.AppManager.apk.signing.SignerInfo;
 import io.github.muntashirakon.AppManager.rules.RuleType;
 import io.github.muntashirakon.AppManager.rules.compontents.ComponentUtils;
 import io.github.muntashirakon.AppManager.utils.ArrayUtils;
+import io.github.muntashirakon.AppManager.utils.DigestUtils;
 import io.github.muntashirakon.AppManager.utils.LangUtils;
 import io.github.muntashirakon.AppManager.utils.PackageUtils;
 import io.github.muntashirakon.AppManager.utils.ThreadUtils;
@@ -48,12 +54,12 @@ public class ApkWhatsNewFinder {
     public static final int CHANGE_INFO = 3;
 
     public static final int VERSION_INFO = 0;
-    public static final int TRACKER_INFO = 1;
-    public static final int SIGNING_CERT_SHA256 = 2;
-    public static final int PERMISSION_INFO = 3;
-    public static final int COMPONENT_INFO = 4;
-    public static final int FEATURE_INFO = 5;
-    public static final int SDK_INFO = 6;
+    public static final int SDK_INFO = 1;
+    public static final int TRACKER_INFO = 2;
+    public static final int SIGNING_CERT_SHA256 = 3;
+    public static final int PERMISSION_INFO = 4;
+    public static final int COMPONENT_INFO = 5;
+    public static final int FEATURE_INFO = 6;
 
     private static final int INFO_COUNT = 7;
 
@@ -129,8 +135,8 @@ public Change[][] getWhatsNew(@NonNull Context context, @NonNull PackageInfo new
             return changes;
         }
         // Sha256 of signing certificates
-        Set<String> newCertSha256 = new HashSet<>(Arrays.asList(PackageUtils.getSigningCertSha256Checksum(newPkgInfo, true)));
-        Set<String> oldCertSha256 = new HashSet<>(Arrays.asList(PackageUtils.getSigningCertSha256Checksum(oldPkgInfo)));
+        Set<String> newCertSha256 = getReadableSignerInfo(PackageUtils.getSignerInfo(newPkgInfo, true));
+        Set<String> oldCertSha256 = getReadableSignerInfo(PackageUtils.getSignerInfo(oldPkgInfo, false));
         List<Change> certSha256Changes = new ArrayList<>();
         certSha256Changes.add(new Change(CHANGE_INFO, componentInfo[SIGNING_CERT_SHA256]));
         certSha256Changes.addAll(findChanges(newCertSha256, oldCertSha256));
@@ -211,6 +217,25 @@ private List<Change> findChanges(Set<String> newInfo, Set<String> oldInfo) {
         return changeList;
     }
 
+    private Set<String> getReadableSignerInfo(@Nullable SignerInfo signerInfo) {
+        Set<String> readableSignerInfo = new HashSet<>();
+        X509Certificate[] x509Certificates = signerInfo == null ? null : signerInfo.getAllSignerCerts();
+        if (x509Certificates != null) {
+            for (X509Certificate cert : x509Certificates) {
+                StringBuilder builder = new StringBuilder();
+                try {
+                    String sha = DigestUtils.getHexDigest(DigestUtils.SHA_256, cert.getEncoded());
+                    builder.append(sha.substring(0, 4)).append(" - ");
+                } catch (CertificateEncodingException e) {
+                    throw new RuntimeException(e);
+                }
+                builder.append(CertUtils.getReadableSubject(cert));
+                readableSignerInfo.add(builder.toString());
+            }
+        }
+        return readableSignerInfo;
+    }
+
     public static class Change {
         @ChangeType
         public int changeType;

app/src/main/java/io/github/muntashirakon/AppManager/main/ApplicationItem.java

@@ -45,6 +45,7 @@
 
 import aosp.libcore.util.EmptyArray;
 import io.github.muntashirakon.AppManager.StaticDataset;
+import io.github.muntashirakon.AppManager.apk.signing.CertUtils;
 import io.github.muntashirakon.AppManager.apk.signing.SignerInfo;
 import io.github.muntashirakon.AppManager.backup.BackupUtils;
 import io.github.muntashirakon.AppManager.compat.AppOpsManagerCompat;
@@ -250,11 +251,7 @@ public void generateOtherInfo() {
         } else uidOrAppIds = "";
         // Cert short name
         if (sha != null) {
-            try {
-                issuerShortName = "CN=" + (sha.first).split("CN=", 2)[1];
-            } catch (ArrayIndexOutOfBoundsException e) {
-                issuerShortName = sha.first;
-            }
+            issuerShortName = CertUtils.getReadableSubject(sha.first);
             if (TextUtils.isEmpty(sha.second)) {
                 sha = null;
             }