The strength of the algorithm is not dependent on the language you use. All languages can implement both strong and weak encryption.

First you need to decide what algorithm you want to use. We can't guide you on that, except perhaps to suggest you use Google, because we don't know what your requirements are.

What do you want to encrypt? Do you want one-way encryption so it can't be decrypted, or must the stuff be decrypted?

Do you have to come up with your own completely new algorithm or can you use existing ones? Some web sites use 1024-bit RSA encryption: that's pretty strong; can you implement that? A completely new algorthm that you think up is unlikely to be especially strong.