How to verify RSA signature on Mac OS 10.5?

I use crypto++ to sign message on Windows.

I want to verify the signed message on Mac OS, in my application.

I currently use crypto++ to verify signature on Mac OS.

However I found that Mac OS has Signing and Verifying API.

But in Reading files sample code, the SecTransformExecute function is available in MAC OS 10.7 and later.

Is there "Signing and Verifying" API in Mac OS 1开发者_StackOverflow社区0.5 ? Is there a built-in command which can verify signature ?

I prefer a built-in command or API because of large size of crypto++ on Mac OS. I compile crypto++ for i386 and x86_64, the output is ~9MB. I do UPX compressing to take it down to ~1.6MB, but I think upx's output is not guaranteed to always work as expected.

After seeing AquaticPrime's source code, I think I will switch to openssl.