# Are these constructions secure PRF?

Let f , g be two random functions and h be a hash function. You are asked the following :

• $$F_f (r,m) = f(r) \oplus m$$
• $${F}_{f,g} (r,m) = f(r) \oplus f(m)$$
• $${F}_{f,h} (r,m) = f(r) \oplus h(m)$$
• $${F}_{f,g,h} (r,m) = f(r) \oplus g(h(m))$$
• $${F}_{f,g} (r,m) = f(r) \oplus g(r \oplus m)$$
• $${F}_{f,g,h} (r,m) = f(r) \oplus g(r \oplus h(m))$$

Secure PRF or secure MAC?

Note by Raja Metronetizen
2 years, 1 month ago

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