title: "The security strength of SHA-1 digest algorithm is not sufficient for this key size" while rebuilding on Android Studio
body: <p>I am facing this problem while building the project. Below is the stacktrace. I created a new keystore file for release key but didn't work. </p>
  
  <pre><code>Caused by: java.io.IOException: Failed to generate v1 signature
  at com.android.tools.build.apkzlib.sign.SigningExtension.onOutputZipReadyForUpdate(SigningExtension.java:292)
  at com.android.tools.build.apkzlib.sign.SigningExtension.access$200(SigningExtension.java:53)
  at com.android.tools.build.apkzlib.sign.SigningExtension$1.lambda$beforeUpdate$2(SigningExtension.java:171)
  at com.android.tools.build.apkzlib.zip.ZFile.notify(ZFile.java:2154)
  at com.android.tools.build.apkzlib.zip.ZFile.update(ZFile.java:923)
  at com.android.tools.build.apkzlib.zip.ZFile.close(ZFile.java:1207)
  at com.android.tools.build.apkzlib.zfile.ApkZFileCreator.close(ApkZFileCreator.java:174)
  at com.google.common.io.Closer.close(Closer.java:216)
  at com.android.builder.internal.packaging.IncrementalPackager.close(IncrementalPackager.java:332)
  at com.android.build.gradle.tasks.PackageAndroidArtifact.doTask(PackageAndroidArtifact.java:704)
  at com.android.build.gradle.tasks.PackageAndroidArtifact.splitFullAction(PackageAndroidArtifact.java:515)
  at com.android.build.gradle.tasks.PackageAndroidArtifact.lambda$doFullTaskAction$3(PackageAndroidArtifact.java:396)
  at com.android.build.gradle.internal.scope.BuildElements$ExecutorBasedScheduler$transform$$inlined$forEach$lambda$1.call(BuildElements.kt:121)
  at com.android.build.gradle.internal.scope.BuildElements$ExecutorBasedScheduler$transform$$inlined$forEach$lambda$1.call(BuildElements.kt:110)
  at java.util.concurrent.ForkJoinTask$AdaptedCallable.exec(ForkJoinTask.java:1424)
  at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
  at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
  at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
  at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
  Caused by: java.security.InvalidKeyException: Failed to sign using signer "CERT"
  at com.android.apksig.internal.apk.v1.V1SchemeSigner.signManifest(V1SchemeSigner.java:295)
  at com.android.apksig.internal.apk.v1.V1SchemeSigner.sign(V1SchemeSigner.java:256)
  at com.android.apksig.DefaultApkSignerEngine.outputJarEntries(DefaultApkSignerEngine.java:424)
  at com.android.tools.build.apkzlib.sign.SigningExtension.onOutputZipReadyForUpdate(SigningExtension.java:290)
  ... 18 more
  Caused by: java.security.InvalidKeyException: Failed to sign using SHA1withDSA
  at com.android.apksig.internal.apk.v1.V1SchemeSigner.generateSignatureBlock(V1SchemeSigner.java:519)
  at com.android.apksig.internal.apk.v1.V1SchemeSigner.signManifest(V1SchemeSigner.java:293)
  ... 21 more
  Caused by: java.security.InvalidKeyException: The security strength of SHA-1 digest algorithm is not sufficient for this key size
  at sun.security.provider.DSA.checkKey(DSA.java:104)
  at sun.security.provider.DSA.engineInitSign(DSA.java:136)
  at java.security.Signature$Delegate.init(Signature.java:1152)
  at java.security.Signature$Delegate.chooseProvider(Signature.java:1112)
  at java.security.Signature$Delegate.engineInitSign(Signature.java:1176)
  at java.security.Signature.initSign(Signature.java:527)
  at com.android.apksig.internal.apk.v1.V1SchemeSigner.generateSignatureBlock(V1SchemeSigner.java:515)
  </code></pre>
  
  <p>Followed other questions on the forum but nothing worked. Please help.
  Android Studio Version - 3.2.1</p>
  
  <p><strong>Edit</strong>- Changing the minSdkVersion from 18 to 21 fixed the issue. But not able to figure out the real reason behind this.</p>