Cast-128 Encryption and S-boxes

[campkev]

I am trying to write an interface to another vendor. There spec requires the use of cast-128 encryption. I am trying to use an open-source version but am not getting the same results that they do. I think it has to do with the s-Boxes. I think that they may have different s-boxes than the code I am using, but they are saying that the s-boxes don't have to be identical. Is that right?