Use SelfSignedCertificate to fix test-failure related to small key size (#10620)

Motivation:

Some JDKs dissallow the usage of keysizes < 2048, so we should not use such small keysizes in tests.

This showed up on fedora 32:

```
Caused by: java.security.cert.CertPathValidatorException: Algorithm constraints check failed on keysize limits. RSA 1024bit key used with certificate: CN=tlsclient.  Usage was tls client
        at sun.security.util.DisabledAlgorithmConstraints$KeySizeConstraint.permits(DisabledAlgorithmConstraints.java:817)
        at sun.security.util.DisabledAlgorithmConstraints$Constraints.permits(DisabledAlgorithmConstraints.java:419)
        at sun.security.util.DisabledAlgorithmConstraints.permits(DisabledAlgorithmConstraints.java:167)
        at sun.security.provider.certpath.AlgorithmChecker.check(AlgorithmChecker.java:326)
        at sun.security.provider.certpath.PKIXMasterCertPathValidator.validate(PKIXMasterCertPathValidator.java:125)
        ... 23 more
```

Modifications:

Replace hardcoded keys / certs with SelfSignedCertificate

Result:

No test-failures related to small key sizes anymore.

handler/src/test/java/io/netty/handler/ssl/SSLEngineTest.java

@@ -59,6 +59,7 @@ import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
 import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.Closeable;
 import java.io.File;
 import java.io.FileInputStream;
@@ -69,6 +70,7 @@ import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.nio.ByteBuffer;
 import java.nio.channels.ClosedChannelException;
+import java.nio.file.Files;
 import java.security.KeyStore;
 import java.security.KeyStoreException;
 import java.security.NoSuchAlgorithmException;
@@ -131,71 +133,6 @@ import static org.mockito.Mockito.verify;
 
 public abstract class SSLEngineTest {
 
-    private static final String X509_CERT_PEM =
-            "-----BEGIN CERTIFICATE-----\n" +
-                    "MIIB9jCCAV+gAwIBAgIJAO9fzyjyV5BhMA0GCSqGSIb3DQEBCwUAMBQxEjAQBgNV\n" +
-                    "BAMMCWxvY2FsaG9zdDAeFw0xNjA5MjAxOTI0MTVaFw00NDEwMDMxOTI0MTVaMBQx\n" +
-                    "EjAQBgNVBAMMCWxvY2FsaG9zdDCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEA\n" +
-                    "1Kp6DmwRiI+TNs3rZ3WvceDYQ4VTxZQk9jgHVKhHTeA0LptOaazbm9g+aOPiCc6V\n" +
-                    "5ysu8T8YRLWjej3by2/1zPBO1k25dQRK8dHr0Grmo20FW7+ES+YxohOfmi7bjOVm\n" +
-                    "NrI3NoVZjf3fQjAlrtKCmaxRPgYEwOT0ucGfJiEyV9cCAwEAAaNQME4wHQYDVR0O\n" +
-                    "BBYEFIba521hTU1P+1QHcIqAOdAEgd1QMB8GA1UdIwQYMBaAFIba521hTU1P+1QH\n" +
-                    "cIqAOdAEgd1QMAwGA1UdEwQFMAMBAf8wDQYJKoZIhvcNAQELBQADgYEAHG5hBy0b\n" +
-                    "ysXKJqWQ/3bNId3VCzD9U557oxEYYAuPG0TqyvjvZ3wNQto079Na7lYkTt2kTIYN\n" +
-                    "/HPW2eflDyXAwXmdNM1Gre213NECY9VxDBTCYJ1R4f2Ogv9iehwzZ4aJGxEDay69\n" +
-                    "wrGrxKIrKL4OMl/E+R4mi+yZ0i6bfQuli5s=\n" +
-                    "-----END CERTIFICATE-----\n";
-
-    private static final String PRIVATE_KEY_PEM =
-            "-----BEGIN PRIVATE KEY-----\n" +
-                    "MIICdgIBADANBgkqhkiG9w0BAQEFAASCAmAwggJcAgEAAoGBANSqeg5sEYiPkzbN\n" +
-                    "62d1r3Hg2EOFU8WUJPY4B1SoR03gNC6bTmms25vYPmjj4gnOlecrLvE/GES1o3o9\n" +
-                    "28tv9czwTtZNuXUESvHR69Bq5qNtBVu/hEvmMaITn5ou24zlZjayNzaFWY3930Iw\n" +
-                    "Ja7SgpmsUT4GBMDk9LnBnyYhMlfXAgMBAAECgYAeyc+B5wNi0eZuOMGr6M3Nns+w\n" +
-                    "dsz5/cicHOBy0SoBjEQBu1pO0ke4+EWQye0fnlj1brsNEiVhTSqtt+bqPPtIvKtZ\n" +
-                    "U4Z2M5euUQL390LnVM+jlaRyKUFVYzFnWfNgciT6SLsrbGRz9EhMH2jM6gi8O/cI\n" +
-                    "n8Do9fgHon9dILOPAQJBAO/3xc0/sWP94Cv25ogsvOLRgXY2NqY/PDfWat31MFt4\n" +
-                    "pKh9aad7SrqR7oRXIEuJ+16drM0O+KveJEjFnHgcq18CQQDi38CqycxrsL2pzq53\n" +
-                    "XtlhbzOBpDaNjySMmdg8wIXVVGmFC7Y2zWq+cEirrI0n2BJOC4LLDNvlT6IjnYqF\n" +
-                    "qp6JAkBQfB0Wyz8XF4aBmG0XzVGJDdXLLUHFHr52x+7OBTez5lHrxSyTpPGag+mo\n" +
-                    "74QAcgYiZOYZXOUg1//5fHYPfyYnAkANKyenwibXaV7Y6GJAE4VSnn3C3KE9/j0E\n" +
-                    "3Dks7Y/XHhsx2cgtziaP/zx4mn9m/KezV/+zgX+SA9lJb++GaqzhAkEAoNfjQ4jd\n" +
-                    "3fsY99ZVoC5YFASSKf+DBqcVOkiUtF1pRwBzLDgKW14+nM/v7X+HJzkfnNTj4cW/\n" +
-                    "nUq37uAS7oJc4g==\n" +
-                    "-----END PRIVATE KEY-----\n";
-
-    private static final String CLIENT_X509_CERT_PEM =
-            "-----BEGIN CERTIFICATE-----\n" +
-                    "MIIBmTCCAQICAQEwDQYJKoZIhvcNAQELBQAwFDESMBAGA1UEAwwJbG9jYWxob3N0\n" +
-                    "MCAXDTE3MDkyMTAzNDUwMVoYDzIxMTcwOTIyMDM0NTAxWjAUMRIwEAYDVQQDEwl0\n" +
-                    "bHNjbGllbnQwgZ8wDQYJKoZIhvcNAQEBBQADgY0AMIGJAoGBAMHX2Jc5i3I+npww\n" +
-                    "mIb0L1A3D+ujpJam/0fTA9w8GFZGs8Em9emlVbEwzFi4kVIoLxwZGqkr6TSH2iaf\n" +
-                    "aX5zVF4oUQyLRyxlFkwaORRi/T+iXq2XPQIW9A5TmVHGSHUlYj8/X9vfrMkJO/I0\n" +
-                    "RXi6mMBXV4C7bu3BLyEGs8rb6kirAgMBAAEwDQYJKoZIhvcNAQELBQADgYEAYLYI\n" +
-                    "5wvUaGRqJn7pA4xR9nEhsNpQbza3bJayQvyiJsB5rn9yBJsk5ch3tBBCfh/MA6PW\n" +
-                    "xcy2hS5rhZUTve6FK3Kr2GiUYy+keYmbna1UJPKPgIR3BX66g+Ev5RUinmbieC2J\n" +
-                    "eE0EtFfLq3uzj8HjakuxOGJz9h+bnCGBhgWWOBo=\n" +
-                    "-----END CERTIFICATE-----\n";
-
-    private static final String CLIENT_PRIVATE_KEY_PEM =
-            "-----BEGIN PRIVATE KEY-----\n" +
-                    "MIICdwIBADANBgkqhkiG9w0BAQEFAASCAmEwggJdAgEAAoGBAMHX2Jc5i3I+npww\n" +
-                    "mIb0L1A3D+ujpJam/0fTA9w8GFZGs8Em9emlVbEwzFi4kVIoLxwZGqkr6TSH2iaf\n" +
-                    "aX5zVF4oUQyLRyxlFkwaORRi/T+iXq2XPQIW9A5TmVHGSHUlYj8/X9vfrMkJO/I0\n" +
-                    "RXi6mMBXV4C7bu3BLyEGs8rb6kirAgMBAAECgYBKPKrzh5NTJo5CDQ5tKNlx5BSR\n" +
-                    "zzM6iyxbSoJA9zbu29b90zj8yVgfKywnkk/9Yexg23Btd6axepHeltClH/AgD1GL\n" +
-                    "QE9bpeBMm8r+/9v/XR/mn5GjTxspj/q29mqOdg8CrKb8M6r1gtj70r8nI8aqmDwV\n" +
-                    "b6/ZTpsei+tN635Y2QJBAP1FHtIK2Z4t2Ro7oNaiv3s3TsYDlj14ladG+DKi2tW+\n" +
-                    "9PW7AO8rLAx2LWmrilXDFc7UG6hvhmUVkp7wXRCK0dcCQQDD7r3g8lswdEAVI0tF\n" +
-                    "fzJO61vDR12Kxv4flar9GwWdak7EzCp//iYNPWc+S7ONlYRbbI+uKVL/KBlvkU9E\n" +
-                    "4M1NAkEAy0ZGzl5W+1XhAeUJ2jsVZFenqdYHJ584veGAI2QCL7vr763/ufX0jKvt\n" +
-                    "FvrPNLY3MqGa8T1RqJ//5gEVMMm6UQJAKpBJpX1gu/T1GuJw7qcEKcrNQ23Ub1pt\n" +
-                    "SDU+UP+2x4yZkfz8WpO+dm/ZZtoRJnfNqgK6b85AXne6ltcNTlw7nQJBAKnFel18\n" +
-                    "Tg2ea308CyM+SJQxpfmU+1yeO2OYHNmimjWFhQPuxIDP9JUzpW39DdCDdTcd++HK\n" +
-                    "xJ5gsU/5OLk6ySo=\n" +
-                    "-----END PRIVATE KEY-----\n";
-    private static final String CLIENT_X509_CERT_CHAIN_PEM = CLIENT_X509_CERT_PEM + X509_CERT_PEM;
-
     private static final String PRINCIPAL_NAME = "CN=e8ac02fa0d65a84219016045db8b05c485b4ecdf.netty.test";
 
     @Mock
@@ -1744,11 +1681,11 @@ public abstract class SSLEngineTest {
 
     @Test(timeout = 30000)
     public void testMutualAuthSameCertChain() throws Exception {
+        SelfSignedCertificate serverCert = new SelfSignedCertificate();
+        SelfSignedCertificate clientCert = new SelfSignedCertificate();
         serverSslCtx =
-                wrapContext(SslContextBuilder.forServer(
-                        new ByteArrayInputStream(X509_CERT_PEM.getBytes(CharsetUtil.UTF_8)),
-                        new ByteArrayInputStream(PRIVATE_KEY_PEM.getBytes(CharsetUtil.UTF_8)))
-                                 .trustManager(new ByteArrayInputStream(X509_CERT_PEM.getBytes(CharsetUtil.UTF_8)))
+                wrapContext(SslContextBuilder.forServer(serverCert.certificate(), serverCert.privateKey())
+                                .trustManager(clientCert.cert())
                                  .clientAuth(ClientAuth.REQUIRE).sslProvider(sslServerProvider())
                                  .sslContextProvider(serverSslContextProvider())
                                  .protocols(protocols())
@@ -1823,11 +1760,16 @@ public abstract class SSLEngineTest {
             }
         }).bind(new InetSocketAddress(0)).syncUninterruptibly().channel();
 
+        // We create a new chain for certificates which contains 2 certificates
+        ByteArrayOutputStream chainStream = new ByteArrayOutputStream();
+        chainStream.write(Files.readAllBytes(clientCert.certificate().toPath()));
+        chainStream.write(Files.readAllBytes(serverCert.certificate().toPath()));
+
         clientSslCtx =
                 wrapContext(SslContextBuilder.forClient().keyManager(
-                        new ByteArrayInputStream(CLIENT_X509_CERT_CHAIN_PEM.getBytes(CharsetUtil.UTF_8)),
-                        new ByteArrayInputStream(CLIENT_PRIVATE_KEY_PEM.getBytes(CharsetUtil.UTF_8)))
-                .trustManager(new ByteArrayInputStream(X509_CERT_PEM.getBytes(CharsetUtil.UTF_8)))
+                        new ByteArrayInputStream(chainStream.toByteArray()),
+                        new FileInputStream(clientCert.privateKey()))
+                .trustManager(new FileInputStream(serverCert.certificate()))
                 .sslProvider(sslClientProvider())
                 .sslContextProvider(clientSslContextProvider())
                 .protocols(protocols()).ciphers(ciphers()).build());
@@ -1844,6 +1786,9 @@ public abstract class SSLEngineTest {
         }).connect(serverChannel.localAddress()).syncUninterruptibly().channel();
 
         promise.syncUninterruptibly();
+
+        serverCert.delete();
+        clientCert.delete();
     }
 
     @Test