GamUtilsEO add functions for PKCE

Author: sgrampone

gamutils/src/main/java/com/genexus/gam/GamUtilsEO.java

@@ -1,6 +1,7 @@
 package com.genexus.gam;
 
 import com.genexus.gam.utils.Encoding;
+import com.genexus.gam.utils.Pkce;
 import com.genexus.gam.utils.Random;
 import com.genexus.gam.utils.cryptography.Encryption;
 import com.genexus.gam.utils.cryptography.Hash;
@@ -95,5 +96,11 @@ public static String base64ToBase64Url(String base64) {
 
 	public static String base64ToHexa(String base64) { return Encoding.base64ToHexa(base64); }
 
+	//**PKCE**//
+
+	public static String pkce_create(int len, String option) { return Pkce.create(len, option); }
+
+	public static boolean pkce_verify(String code_verifier, String code_challenge, String option) { return Pkce.verify(code_verifier, code_challenge, option); }
+
 	/********EXTERNAL OBJECT PUBLIC METHODS  - END ********/
 }

gamutils/src/main/java/com/genexus/gam/utils/Pkce.java

@@ -0,0 +1,54 @@
+package com.genexus.gam.utils;
+
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.bouncycastle.crypto.Digest;
+import org.bouncycastle.crypto.digests.SHA256Digest;
+import org.bouncycastle.util.encoders.UrlBase64;
+
+import java.nio.charset.StandardCharsets;
+import java.text.MessageFormat;
+
+@SuppressWarnings("LoggingSimilarMessage")
+public class Pkce {
+
+	private static final Logger logger = LogManager.getLogger(Pkce.class);
+
+	public static String create(int len, String option) {
+		logger.trace("create");
+		String code_verifier = Random.alphanumeric(len);
+		switch (option.toUpperCase().trim()) {
+			case "S256":
+				byte[] digest = hash(new SHA256Digest(), code_verifier.getBytes(StandardCharsets.UTF_8));
+				return MessageFormat.format("{0},{1}", code_verifier.trim(), new String(UrlBase64.encode(digest)));
+			case "PLAIN":
+				return MessageFormat.format("{0},{1}", code_verifier.trim(), Encoding.toBase64Url(code_verifier.trim()));
+			default:
+				logger.error("Unknown PKCE option");
+				return "";
+		}
+	}
+
+	public static boolean verify(String code_verifier, String code_challenge, String option) {
+		logger.trace("verify");
+		switch (option.toUpperCase().trim()) {
+			case "S256":
+				byte[] digest = hash(new SHA256Digest(), code_verifier.trim().getBytes(StandardCharsets.UTF_8));
+				return (new String(UrlBase64.encode(digest))).equals(code_challenge.trim());
+			case "PLAIN":
+				byte[] bytes_plain = UrlBase64.decode(code_challenge.trim().getBytes(StandardCharsets.UTF_8));
+				return new String(bytes_plain).equals(code_verifier.trim());
+			default:
+				logger.error("Unknown PKCE option");
+				return false;
+		}
+	}
+
+	private static byte[] hash(Digest digest, byte[] inputBytes) {
+		byte[] retValue = new byte[digest.getDigestSize()];
+		digest.update(inputBytes, 0, inputBytes.length);
+		digest.doFinal(retValue, 0);
+		return retValue;
+	}
+}

gamutils/src/test/java/com/genexus/gam/utils/test/PkceTest.java

@@ -0,0 +1,42 @@
+package com.genexus.gam.utils.test;
+
+import com.genexus.gam.GamUtilsEO;
+import com.genexus.gam.utils.Pkce;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.text.MessageFormat;
+
+public class PkceTest {
+
+	@Test
+	public void testPkceS256()
+	{
+		int i = 0;
+		while (i<50)
+		{
+			String[] s256_true = GamUtilsEO.pkce_create(20, "S256").split(",");
+			Assert.assertTrue("testPkceS256 true", GamUtilsEO.pkce_verify(s256_true[0], s256_true[1], "S256"));
+
+			String[] s256_false = GamUtilsEO.pkce_create(20, "S256").split(",");
+			Assert.assertFalse("testPkceS256 false", GamUtilsEO.pkce_verify(MessageFormat.format("{0}tralala",s256_false[0]), s256_false[1], "S256"));
+			i++;
+		}
+	}
+
+	@Test
+	public void testPkcePlain()
+	{
+		int i = 0;
+		while (i<50)
+		{
+			String[] plain_true = GamUtilsEO.pkce_create(20, "PLAIN").split(",");
+			Assert.assertTrue("testPkceS256", GamUtilsEO.pkce_verify(plain_true[0], plain_true[1], "PLAIN"));
+
+			String[] plain_false = GamUtilsEO.pkce_create(20, "PLAIN").split(",");
+			Assert.assertFalse("testPkceS256 false", GamUtilsEO.pkce_verify(MessageFormat.format("{0}tralala",plain_false[0]), plain_false[1], "PLAIN"));
+			i++;
+		}
+	}
+
+}