feat(curve25519.js): Introduce Curve25519 key pairs

curve25519.js

@@ -0,0 +1,36 @@
+const alloc = require('buffer-alloc-unsafe')
+const kp = require('./key-pair')
+
+const {
+ crypto_sign_ed25519_pk_to_curve25519,
+ crypto_sign_ed25519_sk_to_curve25519,
+ crypto_scalarmult_BYTES,
+} = require('sodium-universal')
+
+/**
+ * Generate a Curve25519 public and secret key pair from an optional
+ * seed buffer. This function calls crypto_sign_seed_keypair and
+ * crypto_sign_keypair internally and converts to Curve25519 key pair
+ * calling crypto_sign_ed25519_pk_to_curve25519 and
+ * crypto_sign_ed25519_sk_to_curve25519.
+ * @public
+ * @param {(Buffer)} [seed]
+ * @return {Object}
+ * @throws TypeError
+ */
+function keyPair(seed) {
+ const { publicKey, secretKey } = kp.keyPair(seed)
+ const out = {
+ publicKey: alloc(crypto_scalarmult_BYTES),
+ secretKey: alloc(crypto_scalarmult_BYTES),
+ }
+
+ crypto_sign_ed25519_pk_to_curve25519(out.publicKey, publicKey)
+ crypto_sign_ed25519_sk_to_curve25519(out.secretKey, secretKey)
+
+ return out
+}
+
+module.exports = {
+ keyPair
+}