By definition, the Franklin Reiter related message attack works in a scenario where two messages differ only by a fixed known difference. Suppose I have two messages encrypted by RSA with the same public key (N, e), where:
M1 = "Hello " + name1 + message
M2 = "Hello " + name2 + message
How can I perform the Franklin-Reiter related message attack on them?
I am aware that we need (N, e, C1, C2, f) for a Franklin Reiter related message attack where f = ax + b, but what is f in this case?