diff --git a/src/Core.php b/src/Core.php
index 0c2822f..17e6f5a 100644
--- a/src/Core.php
+++ b/src/Core.php
@@ -27,12 +27,7 @@ public static function incrementCounter($ctr, $inc, &$config)
     {
         static $ivsize = null;
         if ($ivsize === null) {
-            $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
-            if ($ivsize === false) {
-                throw new Ex\CannotPerformOperationException(
-                    "Problem obtaining the correct nonce length."
-                );
-            }
+            $ivsize = self::cipherIvLength($config->cipherMethod());
         }
 
         if (self::ourStrlen($ctr) !== $ivsize) {
@@ -73,6 +68,27 @@ public static function incrementCounter($ctr, $inc, &$config)
         return $ctr;
     }
 
+    /**
+     * Returns the cipher initialization vector (iv) length.
+     *
+     * @param string $method
+     * @return int
+     * @throws Ex\CannotPerformOperationException
+     */
+    public static function cipherIvLength($method)
+    {
+        self::ensureFunctionExists('openssl_cipher_iv_length');
+        $ivsize = \openssl_cipher_iv_length($method);
+
+        if ($ivsize === false || $ivsize <= 0) {
+            throw new Ex\CannotPerformOperationException(
+                'Could not get the IV length from OpenSSL'
+            );
+        }
+
+        return $ivsize;
+    }
+
     /**
      * Returns a random binary string of length $octets bytes.
      *
diff --git a/src/Crypto.php b/src/Crypto.php
index 2ae39b3..207090f 100755
--- a/src/Crypto.php
+++ b/src/Crypto.php
@@ -105,13 +105,7 @@ public static function encrypt($plaintext, $key, $raw_binary = false)
         );
 
         // Generate a random initialization vector.
-        Core::ensureFunctionExists("openssl_cipher_iv_length");
-        $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
-        if ($ivsize === false || $ivsize <= 0) {
-            throw new Ex\CannotPerformOperationException(
-                "Could not get the IV length from OpenSSL"
-            );
-        }
+        $ivsize = Core::cipherIvLength($config->cipherMethod());
         $iv = Core::secureRandom($ivsize);
 
         $ciphertext = $salt . $iv . self::plainEncrypt($plaintext, $ekey, $iv, $config);
@@ -210,13 +204,7 @@ public static function decrypt($ciphertext, $key, $raw_binary = false)
             $ekey = Core::HKDF($config->hashFunctionName(), $key, $config->keyByteSize(), $config->encryptionInfoString(), $salt, $config);
 
             // Extract the initialization vector from the ciphertext.
-            Core::EnsureFunctionExists("openssl_cipher_iv_length");
-            $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
-            if ($ivsize === false || $ivsize <= 0) {
-                throw new Ex\CannotPerformOperationException(
-                    "Could not get the IV length from OpenSSL"
-                );
-            }
+            $ivsize = Core::cipherIvLength($config->cipherMethod());
             if (Core::ourStrlen($ciphertext) <= $ivsize) {
                 throw new Ex\InvalidCiphertextException(
                     "Ciphertext is too short."
@@ -302,13 +290,7 @@ public static function legacyDecrypt($ciphertext, $key)
             );
 
             // Extract the initialization vector from the ciphertext.
-            Core::EnsureFunctionExists("openssl_cipher_iv_length");
-            $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
-            if ($ivsize === false || $ivsize <= 0) {
-                throw new Ex\CannotPerformOperationException(
-                    "Could not get the IV length from OpenSSL"
-                );
-            }
+            $ivsize = Core::cipherIvLength($config->cipherMethod());
             if (Core::ourStrlen($ciphertext) <= $ivsize) {
                 throw new Ex\InvalidCiphertextException(
                     "Ciphertext is too short."
diff --git a/src/File.php b/src/File.php
index 82ee859..5475422 100644
--- a/src/File.php
+++ b/src/File.php
@@ -273,13 +273,7 @@ public static function encryptResource($inputHandle, $outputHandle, Key $key)
         /**
          *  Generate a random initialization vector.
          */
-        Core::ensureFunctionExists("openssl_cipher_iv_length");
-        $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
-        if ($ivsize === false || $ivsize <= 0) {
-            throw new Ex\CannotPerformOperationException(
-                'Improper IV size'
-            );
-        }
+        $ivsize = Core::cipherIvLength($config->cipherMethod());
         $iv = Core::secureRandom($ivsize);
 
         /**
@@ -459,7 +453,7 @@ public static function decryptResource($inputHandle, $outputHandle, Key $key)
              *
              * It should be the first N blocks of the file (N = 16)
              */
-            $ivsize = \openssl_cipher_iv_length($config->cipherMethod());
+            $ivsize = Core::cipherIvLength($config->cipherMethod());
             $iv = self::readBytes($inputHandle, $ivsize);
 
             // How much do we increase the counter after each buffered encryption to prevent nonce reuse