1 files changed, 78 insertions, 0 deletions
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/Hex.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/Hex.java
new file mode 100644
index 0000000000..925159830e
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/Hex.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2020, Michael Dardis. and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.util;
+
+import java.text.MessageFormat;
+
+import org.eclipse.jgit.internal.JGitText;
+
+/**
+ * Encodes and decodes to and from hexadecimal notation.
+ *
+ * @since 5.7
+ */
+public final class Hex {
+
+	private static final char[] HEX = "0123456789abcdef".toCharArray(); //$NON-NLS-1$
+
+	/** Defeats instantiation. */
+	private Hex() {
+		// empty
+	}
+
+	/**
+	 * Decode a hexadecimal string to a byte array.
+	 *
+	 * Note this method validates that characters in the given string are valid
+	 * as digits in a hex string.
+	 *
+	 * @param s
+	 *            hexadecimal string
+	 * @return decoded array
+	 */
+	public static byte[] decode(String s) {
+		int len = s.length();
+		byte[] b = new byte[len / 2];
+
+		for (int i = 0; i < len; i += 2) {
+			int left = Character.digit(s.charAt(i), 16);
+			int right = Character.digit(s.charAt(i + 1), 16);
+
+			if (left == -1 || right == -1) {
+				throw new IllegalArgumentException(MessageFormat.format(
+						JGitText.get().invalidHexString,
+						s));
+			}
+
+			b[i / 2] = (byte) (left << 4 | right);
+		}
+		return b;
+	}
+
+	/**
+	 * Encode a byte array to a hexadecimal string.
+	 *
+	 * @param b byte array
+	 * @return hexadecimal string
+	 */
+	public static String toHexString(byte[] b) {
+		char[] c = new char[b.length * 2];
+
+		for (int i = 0; i < b.length; i++) {
+			int v = b[i] & 0xFF;
+
+			c[i * 2] = HEX[v >>> 4];
+			c[i * 2 + 1] = HEX[v & 0x0F];
+		}
+
+		return new String(c);
+	}
+}