Add y64 encoder

2 files changed, 65 insertions, 0 deletions

diff --git a/security-utils/src/main/java/com/yahoo/security/YBase64.java b/security-utils/src/main/java/com/yahoo/security/YBase64.java
new file mode 100644
index 00000000000..3c0c61c6d89
--- /dev/null
+++ b/security-utils/src/main/java/com/yahoo/security/YBase64.java
@@ -0,0 +1,38 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package com.yahoo.security;
+
+import java.util.Base64;
+
+/**
+ * Variant of {@link java.util.Base64} with the following modifications:
+ * - {@code +} is replaced by {@code .}
+ * - {@code /} is replaced by {code _}
+ * - {@code =} is replaced by {code -}
+ *
+ * @author bjorncs
+ */
+public class YBase64 {
+    private YBase64() {}
+
+    public static byte[] decode(byte[] in) {
+        byte[] rewritten = new byte[in.length];
+        for (int i = 0; i < in.length; i++) {
+            if (in[i] == '.') rewritten[i] = '+';
+            else if (in[i] == '_') rewritten[i] = '/';
+            else if (in[i] == '-') rewritten[i] = '=';
+            else rewritten[i] = in[i];
+        }
+        return Base64.getDecoder().decode(rewritten);
+    }
+
+    public static byte[] encode(byte[] in) {
+        byte[] encoded = Base64.getEncoder().encode(in);
+        for (int i = 0; i < encoded.length; i++) {
+            if (encoded[i] == '+') encoded[i] = '.';
+            else if (encoded[i] == '/') encoded[i] = '_';
+            else if (encoded[i] == '=') encoded[i] = '-';
+        }
+        return encoded;
+    }
+}
diff --git a/security-utils/src/test/java/com/yahoo/security/YBase64Test.java b/security-utils/src/test/java/com/yahoo/security/YBase64Test.java
new file mode 100644
index 00000000000..5853b7a6ef2
--- /dev/null
+++ b/security-utils/src/test/java/com/yahoo/security/YBase64Test.java
@@ -0,0 +1,27 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package com.yahoo.security;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Base64;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author bjorncs
+ */
+class YBase64Test {
+
+    @Test
+    void encodesAndDecodesCorrectly() {
+        var base64Encoded = "+abcd/01234=";
+        byte[] raw = Base64.getDecoder().decode(base64Encoded);
+        assertEquals("+abcd/01234=", new String(Base64.getEncoder().encode(raw)));
+        byte[] ybase64Decoded = YBase64.encode(raw);
+        assertEquals(".abcd_01234-", new String(ybase64Decoded));
+        assertArrayEquals(raw, YBase64.decode(ybase64Decoded));
+    }
+
+}
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