Fix test case failure when extracting cert from signature

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/impl/CertificateGenerator.java

@@ -29,7 +29,6 @@ import io.entgra.device.mgt.core.certificate.mgt.core.util.CertificateManagement
 import io.entgra.device.mgt.core.certificate.mgt.core.util.CommonUtil;
 import io.entgra.device.mgt.core.certificate.mgt.core.util.Serializer;
 import org.apache.commons.codec.binary.Base64;
-import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.bouncycastle.asn1.ASN1Encodable;
@@ -436,7 +435,7 @@ public class CertificateGenerator {
                     String orgUnit = CommonUtil.getSubjectDnAttribute(reqCert,
                             CertificateManagementConstants.ORG_UNIT_ATTRIBUTE);
                     CertificateResponse lookUpCertificate;
-                    if (StringUtils.isNotEmpty(orgUnit)) {
+                    if (CommonUtil.isScepOrgUnit(orgUnit)) {
                         int tenantId = Integer.parseInt(orgUnit.split(("_"))[1]);
                         lookUpCertificate = keyStoreReader.getCertificateBySerial(reqCert.getSerialNumber().toString(),
                                 tenantId);

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/util/CertificateManagementConstants.java

@@ -36,6 +36,7 @@ public final class CertificateManagementConstants {
     public static final String CONF_LOCATION = "conf.location";
     public static final String DEFAULT_PRINCIPAL = "O=WSO2, OU=Mobile, C=LK";
     public static final String ORG_UNIT_ATTRIBUTE = "OU=";
+    public static final String ORG_UNIT_TENANT_PREFIX = "tenant_";
     public static final String RSA_PRIVATE_KEY_BEGIN_TEXT = "-----BEGIN RSA PRIVATE KEY-----\n";
     public static final String RSA_PRIVATE_KEY_END_TEXT = "-----END RSA PRIVATE KEY-----";
     public static final String EMPTY_TEXT = "";

components/certificate-mgt/io.entgra.device.mgt.core.certificate.mgt.core/src/main/java/io/entgra/device/mgt/core/certificate/mgt/core/util/CommonUtil.java

@@ -18,6 +18,7 @@
 package io.entgra.device.mgt.core.certificate.mgt.core.util;
 
 import org.apache.commons.lang.StringUtils;
+import org.apache.commons.lang.math.NumberUtils;
 
 import java.math.BigInteger;
 import java.security.cert.X509Certificate;
@@ -68,4 +69,24 @@ public class CommonUtil {
         }
         return null;
     }
+
+    /**
+     * Checks if the organizational unit (OU) attribute has a valid tenant id in order to verify that it is
+     * a SCEP certificate. eg: OU=tenant_1
+     * <br/><br/>
+     * Refer to engineering mail SCEP implementation for Android
+     * @param orgUnit organizational unit (OU) of the certificate
+     * @return true if it is a valid SCEP org unit else false
+     */
+    public static boolean isScepOrgUnit(String orgUnit) {
+        if (StringUtils.isNotEmpty(orgUnit)) {
+            if (orgUnit.contains(CertificateManagementConstants.ORG_UNIT_TENANT_PREFIX)) {
+                String[] orgUnitArray = orgUnit.split(("_"));
+                if (orgUnitArray.length > 1) {
+                    return NumberUtils.isNumber(orgUnitArray[1]);
+                }
+            }
+        }
+        return false;
+    }
 }