RSA Question

[DWW]

User enters two prime numbers (a and b)
I calculate the prime product of the two (ab)
I calculate phi(ab) = (a - 1)(b - 1)
public key = largest prime of phi(ab) aka coprime of phi(ab)

This is where I'm having trouble--understanding what you do to get the private key.

I MUST code a function that has the prime product (ab) and public key as the ONLY two parameters.

The documentation says that the Private keyis calculated by (phi(55) + 1) / public key
Later on, the specs say the private key is calculated by (1 + PrimeProduct * DiminishedPrimeProduct) / public key

I don't understand what "DiminishedPrimeProduct" means in this circumstance :/ Can anyone clear this up? I'm sure its small detail.

Thanks for any help

 

[DWW]

Basically, given only the PrimeProduct (ab) and the Public Key
Can you create the Private key?

That is what the specs want but I think it would be impossible?

Shouldn't I require the other data (phi(ab)) ?