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+## Shared-key authentication
+
+> **See also**: [Libsodium's documentation on its shared-key authentication features](https://download.libsodium.org/doc/secret-key_cryptography/secret-key_authentication).
+
+### crypto_auth
+
+Get an authenticator for a message for a given key.
+
+**Parameters and their respective types**:
+
+1. `{string|Buffer}` message
+2. `{CryptographyKey}` key
+
+Return a `Promise` that resolves to a `Buffer`.
+
+### crypto_auth_verify
+
+Verify an authenticator for a message for a given key.
+
+**Parameters and their respective types**:
+
+1. `{string|Buffer}` message
+2. `{CryptographyKey}` key
+2. `{Buffer}` mac
+
+Return a `Promise` that resolves to a `boolean`.
+
+### crypto_auth_keygen
+
+Returns a `CryptographyKey` object containing a key appropriate
+for the `crypto_auth` API.
+
+### Example for crypto_auth
+
+```javascript
+const { SodiumPlus } = require('sodium-plus');
+let sodium;
+
+(async function () {
+    if (!sodium) sodium = await SodiumPlus.auto();
+    let plaintext = 'Your message goes here';
+    let key = await sodium.crypto_auth_keygen();
+    let mac = await sodium.crypto_auth(plaintext, key);
+    console.log(await sodium.crypto_auth_verify(plaintext, key, mac));
+})();
+```