diff --git a/doc/Features.md b/doc/Features.md
index b764fd9..ee22a71 100644
--- a/doc/Features.md
+++ b/doc/Features.md
@@ -45,6 +45,14 @@ footprint.
 
 The `File` API looks like this:
 
+* Lazy Mode
+  * `File::checksum`(`lazy`, [`AuthenticationKey?`](Classes/Symmetric/AuthenticationKey.md), `bool?`): `string`
+  * `File::encrypt`(`lazy`, `lazy`, [`EncryptionKey`](Classes/Symmetric/EncryptionKey.md))
+  * `File::decrypt`(`lazy`, `lazy`, [`EncryptionKey`](Classes/Symmetric/EncryptionKey.md))
+  * `File::seal`(`lazy`, `lazy`, [`EncryptionPublicKey`](Classes/Asymmetric/EncryptionPublicKey.md))
+  * `File::unseal`(`lazy`, `lazy`, [`EncryptionSecretKey`](Classes/Asymmetric/EncryptionSecretKey.md))
+  * `File::sign`(`lazy`, [`EncryptionSecretKey`](Classes/Asymmetric/EncryptionSecretKey.md)): `string`
+  * `File::verify`(`lazy`, [`EncryptionPublicKey`](Classes/Asymmetric/EncryptionPublicKey.md)): `bool`
 * Filenames
   * `File::checksumFile`(`string`, [`AuthenticationKey?`](Classes/Symmetric/AuthenticationKey.md), `bool?`): `string`
   * `File::encryptFile`(`string`, `string`, [`EncryptionKey`](Classes/Symmetric/EncryptionKey.md))
@@ -62,6 +70,10 @@ The `File` API looks like this:
   * `File::signResource`(`resource`, [`EncryptionSecretKey`](Classes/Asymmetric/EncryptionSecretKey.md)): `string`
   * `File::verifyResource`(`resource`, [`EncryptionPublicKey`](Classes/Asymmetric/EncryptionPublicKey.md)): `bool`
 
+The `lazy` type indicates that the argument can be either a `string` containing
+the file's path, or a `resource` (open file handle). Don't mix and match types.
+If one is a `resource`, both must be. If the other is a `string`, both must be.
+
 Each of feature is designed to work in a streaming fashion.
 
 > In each case, any call to `::*File` is just a friendly wrapper for 
@@ -73,7 +85,7 @@ Each of feature is designed to work in a streaming fashion.
 Basic usage:
 
 ```php
-$checksum = \ParagonIE\Halite\File::checksumFile('/source/file/path');
+$checksum = \ParagonIE\Halite\File::checksum('/source/file/path');
 ```
 
 If for some reason you desire to use a keyed hash rather than just a plain one,
@@ -81,14 +93,14 @@ you can pass an [`AuthenticationKey`](Classes/Symmetric/AuthenticationKey.md) to
 an optional second parameter, or `null`.
 
 ```php
-$keyed = \ParagonIE\Halite\File::checksumFile('/source/file/path', $auth_key);
+$keyed = \ParagonIE\Halite\File::checksum('/source/file/path', $auth_key);
 ```
 
 Finally, you can pass `true` as the optional third argument if you would like a
 raw binary string rather than a hexadecimal string.
 
 ```php
-$keyed_checksum = \ParagonIE\Halite\File::checksumFile('/source/file/path', null, true);
+$keyed_checksum = \ParagonIE\Halite\File::checksum('/source/file/path', null, true);
 ```
 
 ### Symmetric-Key File Encryption / Decryption
@@ -100,7 +112,7 @@ API. To work around these limitations, use `File::encryptFile()` instead.
 For example:
 
 ```php
-\ParagonIE\Halite\File::encryptFile(
+\ParagonIE\Halite\File::encrypt(
     $inputFilename,
     $outputFilename,
     $enc_key
@@ -134,7 +146,7 @@ $seal_public = $seal_keypair->getPublicKey();
 **Sealing** the contents of a file using Halite:
 
 ```php
-\ParagonIE\Halite\File::sealFile(
+\ParagonIE\Halite\File::seal(
     $inputFilename,
     $outputFilename,
     $seal_public
@@ -144,7 +156,7 @@ $seal_public = $seal_keypair->getPublicKey();
 **Opening** the contents of a sealed file using Halite:
 
 ```php
-\ParagonIE\Halite\File::unsealFile(
+\ParagonIE\Halite\File::unseal(
     $inputFilename,
     $outputFilename,
     $seal_secret
@@ -164,7 +176,7 @@ $sign_keypair = \ParagonIE\Halite\SignatureKeyPair::generate();
 **Signing** the contents of a file using your secret key:
 
 ```php
-$signature = \ParagonIE\Halite\File::signFile(
+$signature = \ParagonIE\Halite\File::sign(
     $inputFilename,
     $sign_secret
 );
@@ -173,7 +185,7 @@ $signature = \ParagonIE\Halite\File::signFile(
 **Verifying** the contents of a file using a known public key:
 
 ```php
-$valid = \ParagonIE\Halite\File::verifyFile(
+$valid = \ParagonIE\Halite\File::verify(
     $inputFilename,
     $sign_public,
     $signature
diff --git a/src/File.php b/src/File.php
index c51819b..3628e01 100644
--- a/src/File.php
+++ b/src/File.php
@@ -82,7 +82,7 @@ public static function decrypt(
     }
     
     /**
-     * Encrypt a file with a public key
+     * Lazy fallthrough method for sealFile() and sealResource()
      * 
      * @param string|resource $input
      * @param string|resource $output
@@ -103,6 +103,76 @@ public static function seal(
         );
     }
     
+    /**
+     * Lazy fallthrough method for sealFile() and sealResource()
+     * 
+     * @param string|resource $input
+     * @param string|resource $output
+     * @param EncryptionSecretKey $secretkey
+     */
+    public static function unseal(
+        $input,
+        $output,
+        EncryptionSecretKey $secretkey
+    ) {
+        if (\is_resource($input) && \is_resource($output)) {
+            return self::unsealResource($input, $output, $secretkey);
+        } elseif (\is_string($input) && \is_string($output)) {
+            return self::unsealFile($input, $output, $secretkey);
+        }
+        throw new \InvalidArgumentException(
+            'Strings or file handles expected'
+        );
+    }
+    
+    /**
+     * Lazy fallthrough method for signFile() and signResource()
+     * 
+     * @param string|resource $filename
+     * @param SignatureSecretKey $secretkey
+     * @param bool $raw_binary
+     * 
+     * @return string
+     */
+    public static function sign(
+        $filename,
+        SignatureSecretKey $secretkey,
+        $raw_binary = false
+    ) {
+        if (\is_resource($filename)) {
+            return self::signResource($filename, $secretkey, $raw_binary);
+        } elseif (\is_string($filename)) {
+            return self::signFile($filename, $secretkey, $raw_binary);
+        }
+        throw new \InvalidArgumentException(
+            'String or file handle expected'
+        );
+    }
+    
+    /**
+     * Lazy fallthrough method for verifyFile() and verifyResource()
+     * 
+     * @param string|resource $filename
+     * @param SignaturePublicKey $publickey
+     * @param bool $raw_binary
+     * 
+     * @return string
+     */
+    public static function verify(
+        $filename,
+        SignaturePublicKey $publickey,
+        $raw_binary = false
+    ) {
+        if (\is_resource($filename)) {
+            return self::verifyResource($filename, $publickey, $raw_binary);
+        } elseif (\is_string($filename)) {
+            return self::verifyFile($filename, $publickey, $raw_binary);
+        }
+        throw new \InvalidArgumentException(
+            'String or file handle expected'
+        );
+    }
+    
     /**
      * Calculate a checksum (derived from BLAKE2b) of a file
      * 
diff --git a/src/SignatureKeyPair.php b/src/SignatureKeyPair.php
index 7e3e26f..c85d49d 100644
--- a/src/SignatureKeyPair.php
+++ b/src/SignatureKeyPair.php
@@ -2,6 +2,7 @@
 namespace ParagonIE\Halite;
 
 use ParagonIE\Halite\Asymmetric\SignatureSecretKey;
+use ParagonIE\Halite\Asymmetric\SignaturePublicKey;
 use ParagonIE\Halite\Alerts as CryptoException;
 
 /**
diff --git a/test/unit/FileLazyTest.php b/test/unit/FileLazyTest.php
new file mode 100644
index 0000000..de5120d
--- /dev/null
+++ b/test/unit/FileLazyTest.php
@@ -0,0 +1,191 @@
+<?php
+use \ParagonIE\Halite\File;
+use \ParagonIE\Halite\EncryptionKeyPair;
+use \ParagonIE\Halite\SignatureKeyPair;
+use \ParagonIE\Halite\Symmetric\EncryptionKey;
+use \ParagonIE\Halite\Alerts as CryptoException;
+
+/**
+ * @backupGlobals disabled
+ * @backupStaticAttributes disabled
+ */
+class FileLazyTest extends PHPUnit_Framework_TestCase
+{
+    public function testEncrypt()
+    {
+        \touch(__DIR__.'/tmp/paragon_avatar.encrypted.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.encrypted.png', 0777);
+        \touch(__DIR__.'/tmp/paragon_avatar.decrypted.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.decrypted.png', 0777);
+        
+        $key = new EncryptionKey(\str_repeat('B', 32));
+        File::encrypt(
+            __DIR__.'/tmp/paragon_avatar.png',
+            __DIR__.'/tmp/paragon_avatar.encrypted.png',
+            $key
+        );
+        
+        File::decrypt(
+            __DIR__.'/tmp/paragon_avatar.encrypted.png',
+            __DIR__.'/tmp/paragon_avatar.decrypted.png',
+            $key
+        );
+        
+        $this->assertEquals(
+            \hash_file('sha256', __DIR__.'/tmp/paragon_avatar.png'),
+            \hash_file('sha256', __DIR__.'/tmp/paragon_avatar.decrypted.png')
+        );
+    }
+    
+    public function testEncryptFail()
+    {
+        \touch(__DIR__.'/tmp/paragon_avatar.encrypt_fail.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.encrypt_fail.png', 0777);
+        \touch(__DIR__.'/tmp/paragon_avatar.decrypt_fail.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.decrypt_fail.png', 0777);
+        
+        $key = new EncryptionKey(\str_repeat('B', 32));
+        File::encrypt(
+            __DIR__.'/tmp/paragon_avatar.png',
+            __DIR__.'/tmp/paragon_avatar.encrypt_fail.png',
+            $key
+        );
+        
+        $fp = \fopen(__DIR__.'/tmp/paragon_avatar.encrypt_fail.png', 'ab');
+        \fwrite($fp, \Sodium\randombytes_buf(1));
+        fclose($fp);
+            
+        try {
+            File::decrypt(
+                __DIR__.'/tmp/paragon_avatar.encrypt_fail.png',
+                __DIR__.'/tmp/paragon_avatar.decrypt_fail.png',
+                $key
+            );
+            throw new \Exception('ERROR: THIS SHOULD ALWAYS FAIL');
+        } catch (CryptoException\InvalidMessage $e) {
+            $this->assertTrue($e instanceof CryptoException\InvalidMessage);
+        }
+    }
+    
+    public function testSeal()
+    {
+        \touch(__DIR__.'/tmp/paragon_avatar.sealed.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.sealed.png', 0777);
+        \touch(__DIR__.'/tmp/paragon_avatar.opened.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.opened.png', 0777);
+        
+        $keypair = EncryptionKeyPair::generate();
+            $secretkey = $keypair->getSecretKey();
+            $publickey = $keypair->getPublicKey();
+        
+        File::seal(
+            __DIR__.'/tmp/paragon_avatar.png',
+            __DIR__.'/tmp/paragon_avatar.sealed.png',
+            $publickey
+        );
+        
+        File::unseal(
+            __DIR__.'/tmp/paragon_avatar.sealed.png',
+            __DIR__.'/tmp/paragon_avatar.opened.png',
+            $secretkey
+        );
+        
+        $this->assertEquals(
+            \hash_file('sha256', __DIR__.'/tmp/paragon_avatar.png'),
+            \hash_file('sha256', __DIR__.'/tmp/paragon_avatar.opened.png')
+        );
+    }
+    
+    public function testSealFail()
+    {
+        \touch(__DIR__.'/tmp/paragon_avatar.seal_fail.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.seal_fail.png', 0777);
+        \touch(__DIR__.'/tmp/paragon_avatar.open_fail.png');
+        \chmod(__DIR__.'/tmp/paragon_avatar.open_fail.png', 0777);
+        
+        $keypair = EncryptionKeyPair::generate();
+            $secretkey = $keypair->getSecretKey();
+            $publickey = $keypair->getPublicKey();
+        
+        File::seal(
+            __DIR__.'/tmp/paragon_avatar.png',
+            __DIR__.'/tmp/paragon_avatar.seal_fail.png',
+            $publickey
+        );
+        
+        $fp = \fopen(__DIR__.'/tmp/paragon_avatar.seal_fail.png', 'ab');
+        \fwrite($fp, \Sodium\randombytes_buf(1));
+        fclose($fp);
+        
+        try {
+            File::unseal(
+                __DIR__.'/tmp/paragon_avatar.seal_fail.png',
+                __DIR__.'/tmp/paragon_avatar.opened.png',
+                $secretkey
+            );
+            throw new \Exception('ERROR: THIS SHOULD ALWAYS FAIL');
+        } catch (CryptoException\InvalidMessage $e) {
+            $this->assertTrue($e instanceof CryptoException\InvalidMessage);
+        }
+    }
+    
+    public function testSign()
+    {
+        $keypair = SignatureKeyPair::generate();
+            $secretkey = $keypair->getSecretKey();
+            $publickey = $keypair->getPublicKey();
+        
+        $signature = File::sign(
+            __DIR__.'/tmp/paragon_avatar.png',
+            $secretkey
+        );
+        
+        $this->assertTrue(
+            File::verify(
+                __DIR__.'/tmp/paragon_avatar.png',
+                $publickey,
+                $signature
+            )
+        );
+    }
+    
+    public function testChecksum()
+    {
+        $csum = File::checksum(__DIR__.'/tmp/paragon_avatar.png');
+        $this->assertEquals(
+            $csum,
+            "09f9f74a0e742d057ca08394db4c2e444be88c0c94fe9a914c3d3758c7eccafb".
+            "8dd286e3d6bc37f353e76c0c5aa2036d978ca28ffaccfa59f5dc1f076c5517a0"
+        );
+        
+        $data = \Sodium\randombytes_buf(32);
+        \file_put_contents(__DIR__.'/tmp/garbage.dat', $data);
+        
+        $hash = \Sodium\crypto_generichash($data, null, 64);
+        $file = File::checksum(__DIR__.'/tmp/garbage.dat', null, true);
+        $this->assertEquals(
+            $hash,
+            $file
+        );
+    }
+    
+    public function testArgFail()
+    {
+        try {
+            \touch(__DIR__.'/tmp/paragon_avatar.encrypted.png');
+            \chmod(__DIR__.'/tmp/paragon_avatar.encrypted.png', 0777);
+            \touch(__DIR__.'/tmp/paragon_avatar.decrypted.png');
+            \chmod(__DIR__.'/tmp/paragon_avatar.decrypted.png', 0777);
+
+            $key = new EncryptionKey(\str_repeat('B', 32));
+            File::encrypt(
+                __DIR__.'/tmp/paragon_avatar.png',
+                 \fopen(__DIR__.'/tmp/paragon_avatar.encrypted.png', 'wb'),
+                $key
+            );
+            $this->fail('We should be throwing an exception, not failing open.');
+        } catch (\InvalidArgumentException $e) {
+            $this->assertTrue($e instanceof \InvalidArgumentException);
+        }
+    }
+}
\ No newline at end of file
diff --git a/test/unit/FileTest.php b/test/unit/FileTest.php
index eb80659..978ed26 100644
--- a/test/unit/FileTest.php
+++ b/test/unit/FileTest.php
@@ -1,6 +1,5 @@
 <?php
 use \ParagonIE\Halite\File;
-use \ParagonIE\Halite\Key;
 use \ParagonIE\Halite\EncryptionKeyPair;
 use \ParagonIE\Halite\SignatureKeyPair;
 use \ParagonIE\Halite\Symmetric\EncryptionKey;
@@ -132,7 +131,9 @@ public function testSealFail()
     
     public function testSign()
     {
-        list($secretkey, $publickey) = Key::generate(Key::CRYPTO_SIGN);
+        $keypair = SignatureKeyPair::generate();
+            $secretkey = $keypair->getSecretKey();
+            $publickey = $keypair->getPublicKey();
         
         $signature = File::signFile(
             __DIR__.'/tmp/paragon_avatar.png',
@@ -187,6 +188,5 @@ public function testStreamOperations()
         \fclose($fp);
         
         $this->assertEquals($written, $BYTES);
-    }
-    
+    }    
 }