Derive public keys from secret keys.

paragonie · Dec 30, 2015 · 4f90faa · 4f90faa
1 parent 4531fd0
commit 4f90faa
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Showing 4 changed files with 61 additions and 2 deletions.
diff --git a/src/Asymmetric/EncryptionSecretKey.php b/src/Asymmetric/EncryptionSecretKey.php
@@ -11,4 +11,17 @@ public function __construct($keyMaterial = '', ...$args)
     {
         parent::__construct($keyMaterial, false);
     }
+
+    /**
+     * See the appropriate derived class.
+     * 
+     * @return SignaturePublicKey
+     */
+    public function derivePublicKey()
+    {
+        $publicKey = \Sodium\crypto_box_publickey_from_secretkey(
+            $this->get()
+        );
+        return new EncryptionPublicKey($publicKey);
+    }
 }
diff --git a/src/Asymmetric/SecretKey.php b/src/Asymmetric/SecretKey.php
@@ -3,6 +3,7 @@
 
 use \ParagonIE\Halite\Contract;
 use \ParagonIE\Halite\Key;
+use \ParagonIE\Halite\Alerts\CannotPerformOperation;
 
 class SecretKey extends Key implements Contract\KeyInterface
 {
@@ -17,4 +18,14 @@ public function __construct($keyMaterial = '', ...$args)
             : false;
         parent::__construct($keyMaterial, false, $signing, true);
     }
+
+    /**
+     * See the appropriate derived class.
+     */
+    public function derivePublicKey()
+    {
+        throw new CannotPerformOperation(
+            'This is not implemented in the base class'
+        );
+    }
 }
diff --git a/src/Asymmetric/SignatureSecretKey.php b/src/Asymmetric/SignatureSecretKey.php
@@ -11,4 +11,17 @@ public function __construct($keyMaterial = '', ...$args)
     {
         parent::__construct($keyMaterial, true);
     }
+
+    /**
+     * See the appropriate derived class.
+     * 
+     * @return SignaturePublicKey
+     */
+    public function derivePublicKey()
+    {
+        $publicKey = \Sodium\crypto_sign_publickey_from_secretkey(
+            $this->get()
+        );
+        return new SignaturePublicKey($publicKey);
+    }
 }
diff --git a/test/unit/KeyPairTest.php b/test/unit/KeyPairTest.php
@@ -1,7 +1,5 @@
 <?php
 use \ParagonIE\Halite\KeyFactory;
-use \ParagonIE\Halite\KeyPair;
-use \ParagonIE\Halite\Key;
 use \ParagonIE\Halite\Asymmetric\Crypto as Asymmetric;
 use \ParagonIE\Halite\Asymmetric\SecretKey as ASecretKey;
 use \ParagonIE\Halite\Asymmetric\PublicKey as APublicKey;
@@ -56,4 +54,28 @@ public function testFileStorage()
         );
         \unlink($filename);
     }
+
+    /**
+     * @covers \ParagonIE\Halite\Asymmetric\EncryptionSecretKey::derivePublicKey()
+     * @covers \ParagonIE\Halite\Asymmetric\SignatureSecretKey::derivePublicKey()
+     */
+    public function testPublicDerivation()
+    {
+        $enc_kp = KeyFactory::generateEncryptionKeyPair();
+        $enc_secret = $enc_kp->getSecretKey();
+        $enc_public = $enc_kp->getPublicKey();
+
+        $this->assertEquals(
+            $enc_secret->derivePublicKey()->get(),
+            $enc_public->get()
+        );
+
+        $sign_kp = KeyFactory::generateSignatureKeyPair();
+        $sign_secret = $sign_kp->getSecretKey();
+        $sign_public = $sign_kp->getPublicKey();
+        $this->assertEquals(
+            $sign_secret->derivePublicKey()->get(),
+            $sign_public->get()
+        );
+    }
 }