Change DigestUtils.sha256Hex to MessageDigest sha256 to fix commons-c…

…odec problem under Android API 28. (#54)

gradle.properties

@@ -1,3 +1,3 @@
-version=10.2.0
+version=10.2.1
 
 org.gradle.jvmargs=-Xmx2g

src/main/java/com/configcat/RolloutEvaluator.java

@@ -4,6 +4,8 @@
 import org.apache.commons.codec.digest.DigestUtils;
 
 import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.util.*;
 
 class EvaluationResult {
@@ -28,6 +30,9 @@ class RolloutEvaluator {
     public static final String COMPARISON_OPERATOR_IS_INVALID = "Comparison operator is invalid.";
     public static final String CANNOT_EVALUATE_THE_USER_INVALID = " attribute is invalid (";
     public static final String COMPARISON_VALUE_IS_MISSING_OR_INVALID = "Comparison value is missing or invalid.";
+
+    private static final char[] HEX_ARRAY = "0123456789abcdef".toCharArray();
+
     private final ConfigCatLogger logger;
 
     public RolloutEvaluator(ConfigCatLogger logger) {
@@ -519,7 +524,7 @@ private boolean evaluateContainsAnyOf(UserCondition userCondition, String userVa
 
 
     private static String getSaltedUserValue(String userValue, String configJsonSalt, String contextSalt) {
-        return DigestUtils.sha256Hex(userValue + configJsonSalt + contextSalt);
+        return sha256(userValue + configJsonSalt + contextSalt);
     }
 
     private static String getSaltedUserValueSlice(byte[] userValueSliceUTF8, String configJsonSalt, String contextSalt) {
@@ -530,7 +535,34 @@ private static String getSaltedUserValueSlice(byte[] userValueSliceUTF8, String
         System.arraycopy(userValueSliceUTF8, 0, concatByteArrays, 0, userValueSliceUTF8.length);
         System.arraycopy(configSaltByteArray, 0, concatByteArrays, userValueSliceUTF8.length, configSaltByteArray.length);
         System.arraycopy(contextSaltByteArray, 0, concatByteArrays, userValueSliceUTF8.length + configSaltByteArray.length, contextSaltByteArray.length);
-        return DigestUtils.sha256Hex(concatByteArrays);
+        return  sha256(concatByteArrays);
+    }
+
+    private static String bytesToHex(byte[] bytes) {
+        char[] hexChars = new char[bytes.length * 2];
+        int v;
+        for (int j = 0; j < bytes.length; j++) {
+            v = bytes[j] & 0xFF;
+            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
+            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
+        }
+        return new String(hexChars);
+    }
+
+    private static String sha256(String text){
+        byte[] textBytes = text.getBytes(StandardCharsets.UTF_8);
+        return sha256(textBytes);
+    }
+
+    private static String sha256(byte[] byteArray){
+        MessageDigest digest = null;
+        try {
+            digest = MessageDigest.getInstance("SHA-256");
+            byte[] hash = digest.digest(byteArray);
+            return bytesToHex(hash);
+        } catch (NoSuchAlgorithmException e) {
+            throw new RuntimeException(e);
+        }
     }
 
     private boolean evaluateSegmentCondition(SegmentCondition segmentCondition, EvaluationContext context, String configSalt, Segment[] segments, EvaluateLogger evaluateLogger) {

src/main/java/com/configcat/Utils.java

@@ -30,7 +30,7 @@ private Constants() { /* prevent from instantiation*/ }
     static final long DISTANT_PAST = 0;
     static final String CONFIG_JSON_NAME = "config_v6.json";
     static final String SERIALIZATION_FORMAT_VERSION = "v2";
-    static final String VERSION = "10.2.0";
+    static final String VERSION = "10.2.1";
 
     static final String SDK_KEY_PROXY_PREFIX = "configcat-proxy/";
     static final String SDK_KEY_PREFIX = "configcat-sdk-1";