diff --git a/src/Nexus/Encryption/Key.php b/src/Nexus/Encryption/Key.php
new file mode 100644
index 0000000..093dcfa
--- /dev/null
+++ b/src/Nexus/Encryption/Key.php
@@ -0,0 +1,60 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the Nexus framework.
+ *
+ * (c) John Paul E. Balandan, CPA <paulbalandan@gmail.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Nexus\Encryption;
+
+abstract class Key
+{
+    private ?string $keyString;
+
+    public function __construct(Secret $key)
+    {
+        $this->keyString = $key->reveal();
+    }
+
+    public function __destruct()
+    {
+        sodium_memzero($this->keyString);
+    }
+
+    public function __clone(): void
+    {
+        throw new \BadMethodCallException(\sprintf('Cannot clone a %s object.', basename(static::class)));
+    }
+
+    /**
+     * @return array<string, string>
+     */
+    public function __debugInfo(): array
+    {
+        return ['keyString' => '[redacted]'];
+    }
+
+    public function __serialize(): never
+    {
+        throw new \BadMethodCallException(\sprintf('Cannot serialise a %s object.', static::class));
+    }
+
+    /**
+     * @param array<string, mixed> $data
+     */
+    public function __unserialize(array $data): never
+    {
+        throw new \BadMethodCallException(\sprintf('Cannot unserialise a %s object.', static::class)); // @codeCoverageIgnore
+    }
+
+    public function getKeyString(): string
+    {
+        return $this->keyString ?? '';
+    }
+}
diff --git a/tests/Encryption/KeyTest.php b/tests/Encryption/KeyTest.php
new file mode 100644
index 0000000..3f01abe
--- /dev/null
+++ b/tests/Encryption/KeyTest.php
@@ -0,0 +1,90 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * This file is part of the Nexus framework.
+ *
+ * (c) John Paul E. Balandan, CPA <paulbalandan@gmail.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Nexus\Tests\Encryption;
+
+use Nexus\Encryption\Key;
+use Nexus\Encryption\Secret;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @internal
+ */
+#[CoversClass(Key::class)]
+#[Group('unit-test')]
+final class KeyTest extends TestCase
+{
+    private Key&MockObject $key;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->key = $this->getMockBuilder(Key::class)
+            ->setConstructorArgs([new Secret(random_bytes(32))])
+            ->onlyMethods([])
+            ->getMock()
+        ;
+    }
+
+    public function testCannotCloneKey(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+        $this->expectExceptionMessage(\sprintf('Cannot clone a %s object.', \get_class($this->key)));
+
+        clone $this->key; // @phpstan-ignore expr.resultUnused
+    }
+
+    public function testCannotSerialiseKey(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+        $this->expectExceptionMessage(\sprintf('Cannot serialise a %s object.', \get_class($this->key)));
+
+        serialize($this->key);
+    }
+
+    public function testHidesKeyStringFromDump(): void
+    {
+        $secret = new Secret(random_bytes(32));
+        $this->key = $this->getMockBuilder(Key::class)
+            ->setConstructorArgs([$secret])
+            ->onlyMethods([])
+            ->getMock()
+        ;
+
+        ob_start();
+        var_dump($this->key);
+        $dump = (string) ob_get_clean();
+        $print = print_r($this->key, true);
+
+        self::assertStringNotContainsString($secret->reveal(), $dump);
+        self::assertStringContainsString('[redacted]', $dump);
+        self::assertStringNotContainsString($secret->reveal(), $print);
+        self::assertStringContainsString('[redacted]', $print);
+    }
+
+    public function testGetKeyString(): void
+    {
+        $secret = new Secret(random_bytes(32));
+        $this->key = $this->getMockBuilder(Key::class)
+            ->setConstructorArgs([$secret])
+            ->onlyMethods([])
+            ->getMock()
+        ;
+
+        self::assertSame($secret->reveal(), $this->key->getKeyString());
+    }
+}