[Moodles]

Right, but my question is, why is it the correct value? There's some math theorem which makes it true?

m_2 = c^d_q mod q

    = m^(e * d_q) mod q

    = m because?

[pbsd]

That's just how RSA works, via Fermat's little theorem: e * d_q mod (q-1) = 1, so m^(e * d_q) mod q = m^1 mod q = m.

[Moodles]

Got it, thank you!