Added support for seeded key pairs

src/main/java/org/abstractj/kalium/NaCl.java

@@ -200,6 +200,8 @@ int crypto_aead_chacha20poly1305_decrypt(
         @Deprecated
         int BOXZERO_BYTES = 16;
 
+        int CRYPTO_BOX_CURVE25519XSALSA20POLY1305_SEEDBYTES = 32;
+
         int CRYPTO_BOX_CURVE25519XSALSA20POLY1305_PUBLICKEYBYTES = 32;
 
         int CRYPTO_BOX_CURVE25519XSALSA20POLY1305_SECRETKEYBYTES = 32;
@@ -217,7 +219,10 @@ int crypto_aead_chacha20poly1305_decrypt(
         int CRYPTO_BOX_CURVE25519XSALSA20POLY1305_BEFORENMBYTES = 32;
 
         int crypto_scalarmult_base(
-            @Out byte[] publicKey, @In byte[] secretKey);
+                @Out byte[] publicKey, @In byte[] secretKey);
+
+        int crypto_box_curve25519xsalsa20poly1305_seed_keypair(
+                @Out byte[] publicKey, @Out byte[] secretKey, @In byte[] seed);
 
         int crypto_box_curve25519xsalsa20poly1305_keypair(
                 @Out byte[] publicKey, @Out byte[] secretKey);

src/main/java/org/abstractj/kalium/keys/KeyPair.java

@@ -47,6 +47,18 @@ public KeyPair(String secretKey, Encoder encoder) {
         this(encoder.decode(secretKey));
     }
 
+    private KeyPair(byte[] secretKey, byte[] publicKey) {
+        this.secretKey = secretKey;
+        this.publicKey = publicKey;
+    }
+
+    public static KeyPair seeded(byte[] seed) {
+        byte[] secretKey = zeros(CRYPTO_BOX_CURVE25519XSALSA20POLY1305_SECRETKEYBYTES);
+        byte[] publicKey = zeros(CRYPTO_BOX_CURVE25519XSALSA20POLY1305_PUBLICKEYBYTES);
+        sodium().crypto_box_curve25519xsalsa20poly1305_seed_keypair(publicKey, secretKey, seed);
+        return new KeyPair(secretKey, publicKey);
+    }
+
     public PublicKey getPublicKey() {
         return new PublicKey(publicKey);
     }

src/test/java/org/abstractj/kalium/keys/KeyPairTest.java

@@ -16,6 +16,8 @@
 
 package org.abstractj.kalium.keys;
 
+import org.abstractj.kalium.*;
+import org.abstractj.kalium.crypto.*;
 import org.junit.Ignore;
 import org.junit.Test;
 
@@ -41,6 +43,18 @@ public void testGenerateKeyPair() {
         }
     }
 
+    @Test
+    public void testGenerateSeededKeyPair() {
+        try {
+            byte[] seed = new Random().randomBytes(NaCl.Sodium.CRYPTO_BOX_CURVE25519XSALSA20POLY1305_SEEDBYTES);
+            KeyPair key = KeyPair.seeded(seed);
+            assertTrue(key.getPrivateKey() != null);
+            assertTrue(key.getPublicKey() != null);
+        } catch (Exception e) {
+            fail("Should return a valid key size");
+        }
+    }
+
     @Test
     public void testAcceptsValidKey() {
         try {