PRGN in iOS KeyChain

My boss is asking me, which PRGN (Pseudo Random Generator Number) is using our iOS App for encrypting and decrypting data.

We are using the native KeyChain services for storing the data and I don't know what to answer since we are using the KeyChainItemWrapper for accessing the single items i.e. password, ports, etc. in our App and there is not too much reference about this.

I already debugged the app to see if I find something but I couldn't find something yet.

Any help would be appreciated, thanks