Return size of the key in bits

OpenVPN Adapter/OpenVPNPrivateKey.h

@@ -20,6 +20,8 @@
 
 - (nonnull instancetype) __unavailable init;
 
+@property (nonatomic, readonly) NSInteger size;
+
 - (nullable NSData *)pemData:(out NSError * __nullable * __nullable)error;
 - (nullable NSData *)derData:(out NSError * __nullable * __nullable)error;
 

OpenVPN Adapter/OpenVPNPrivateKey.m

@@ -29,6 +29,10 @@
     return self;
 }
 
+- (NSInteger)size {
+    return mbedtls_pk_get_bitlen(self.ctx);
+}
+
 + (nullable OpenVPNPrivateKey *)keyWithPEM:(NSData *)pemData password:(NSString *)password error:(out NSError **)error {
     OpenVPNPrivateKey *key = [OpenVPNPrivateKey new];