diff --git a/nodejs/test/crypto.test.js b/nodejs/test/crypto.test.js
new file mode 100644
index 00000000..d2b1621b
--- /dev/null
+++ b/nodejs/test/crypto.test.js
@@ -0,0 +1,93 @@
+'use strict';
+
+const assert = require('node:assert/strict');
+const { test } = require('node:test');
+const { Certificate, DhtRunner, Identity, PrivateKey, PublicKey, hash } = require('..');
+
+const payload = Buffer.from([0, 255, 1, 0, 42]);
+
+test('RSA keys sign, encrypt, and survive password-protected serialization', async () => {
+    const key = await PrivateKey.generate({ algorithm: 'rsa', bits: 2048 });
+    const publicKey = key.getPublicKey();
+    assert.match(publicKey.getId(), /^[0-9a-f]{40}$/);
+    assert.match(publicKey.getLongId(), /^[0-9a-f]{64}$/);
+    const signature = key.sign(payload);
+    assert.equal(publicKey.checkSignature(payload, signature), true);
+    assert.equal(publicKey.checkSignature(Buffer.from('other'), signature), false);
+    assert.deepEqual(key.decrypt(publicKey.encrypt(payload)), payload);
+    const restored = new PrivateKey(key.serialize('test password'), 'test password');
+    const restoredPublic = new PublicKey(publicKey.serialize());
+    assert.equal(restoredPublic.getLongId(), publicKey.getLongId());
+    assert.equal(restoredPublic.checkSignature(payload, restored.sign(payload)), true);
+    assert.deepEqual(restored.decrypt(restoredPublic.encrypt(payload)), payload);
+    assert.throws(() => new PrivateKey(key.serialize('password'), 'wrong password'));
+    assert.throws(() => key.decrypt(Buffer.from('invalid ciphertext')));
+    assert.throws(() => key.serialize('bad\0password'), TypeError);
+});
+
+test('EC keys sign and invalid crypto inputs raise JS errors', async () => {
+    const key = await PrivateKey.generate();
+    const restored = new PrivateKey(key.serialize());
+    assert.equal(restored.getPublicKey().checkSignature(payload, key.sign(payload)), true);
+    assert.throws(() => key.getPublicKey().encrypt(payload));
+    for (const Type of [PrivateKey, PublicKey, Certificate]) {
+        assert.throws(() => new Type(Buffer.alloc(0)));
+        assert.throws(() => new Type(Buffer.from('not a key or certificate')));
+        assert.throws(() => new Type(null), TypeError);
+    }
+    assert.throws(() => PrivateKey.generate({ algorithm: 'unknown' }), TypeError);
+    assert.throws(() => PrivateKey.generate({ algorithm: 'rsa', bits: 1 }), RangeError);
+    assert.throws(() => PrivateKey.generate({ algorithm: 'rsa', bits: 2048.5 }), RangeError);
+    assert.throws(() => key.sign('not bytes'), TypeError);
+    assert.throws(() => PrivateKey.prototype.sign.call({}, payload), TypeError);
+});
+
+test('identities own matching keys and certificates and support import', async () => {
+    const identity = await Identity.generate('nodejs crypto');
+    const certificate = new Certificate(identity.certificate.serialize());
+    const key = new PrivateKey(identity.privateKey.serialize());
+    const restored = new Identity(key, certificate);
+    assert.equal(restored.certificate.getLongId(), key.getPublicKey().getLongId());
+    assert.equal(certificate.getPublicKey().checkSignature(payload, key.sign(payload)), true);
+    assert.throws(() => new Identity({}, certificate), TypeError);
+    const other = await PrivateKey.generate();
+    assert.throws(() => new Identity(other, certificate), /match/i);
+});
+
+test('signed and encrypted values round-trip between authenticated nodes', { timeout: 30000 }, async () => {
+    const writerIdentity = await Identity.generate('writer');
+    const readerIdentity = await Identity.generate('reader', { algorithm: 'rsa', bits: 2048 });
+    const writer = new DhtRunner();
+    const reader = new DhtRunner();
+    try {
+        writer.run({ port: 0, ipv4: '127.0.0.1', ipv6: '::1', identity: writerIdentity });
+        reader.run({ port: 0, ipv4: '127.0.0.1', ipv6: '::1', identity: readerIdentity });
+        writer.bootstrap('127.0.0.1', reader.getBoundPort());
+        reader.bootstrap('127.0.0.1', writer.getBoundPort());
+        const signedKey = hash('nodejs signed value');
+        assert.equal(await writer.putSigned(signedKey, payload, { id: 41n }), true);
+        const signed = await reader.get(signedKey);
+        assert.ok(signed.some(value => value.data.equals(payload) && value.isSigned));
+        assert.equal(signed[0].owner, writerIdentity.certificate.getLongId());
+        const encryptedKey = hash('nodejs encrypted value');
+        assert.equal(await writer.putEncrypted(encryptedKey, payload, readerIdentity.certificate.getPublicKey(), { id: 42n }), true);
+        const decrypted = await reader.get(encryptedKey);
+        assert.ok(decrypted.some(value => value.data.equals(payload)));
+        assert.throws(() => writer.putEncrypted(encryptedKey, payload, {}), TypeError);
+        assert.throws(() => writer.putEncrypted(encryptedKey, payload, writerIdentity.certificate.getPublicKey()), /RSA/i);
+    } finally {
+        await Promise.all([writer.close(), reader.close()]);
+    }
+});
+
+test('signed operations require an identity and reject stopped runners', async () => {
+    const runner = new DhtRunner();
+    try {
+        assert.throws(() => runner.run({ identity: {} }), TypeError);
+        runner.run({ port: 0, ipv4: '127.0.0.1', ipv6: '::1' });
+        assert.throws(() => runner.putSigned(hash('unsigned'), payload), /identity/i);
+    } finally {
+        await runner.close();
+    }
+    assert.throws(() => runner.putSigned(hash('closed'), payload), /closed/i);
+});
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