# how $C =M^e \bmod N$ can be written as $C = M \cdot k \bmod N$ in RSA algorithm?

• how $$C =M^e \bmod N$$ can be written as $$C = M \cdot k \bmod N$$ in RSA algorithm?

• how $$M =c^d \bmod N$$ can be written as $$M = c.k^{-1} \bmod N$$ in RSA algorithm?

• Welcome to Cryptography. Is this homework? – kelalaka Jan 22 at 9:16
• I fail to see the use of the questions. For the first one, is there anything wrong with the obvious: $k=M^{(e-1)}$, or the usually smaller $k=M^{(e-1)}\bmod N$ ? They both yields a $k$ with $M^e \bmod N\ =\ C\ =\ M\cdot k\bmod N$. – fgrieu Jan 23 at 14:03