Check out the modular multiplicative inverse. This is the equivalent of division modulo some number. Implementing it using the EEA can be tricky, though there is a shortcut.

Also, as Frob says, you have the wrong decryption function. You're trying to get "x" back, not "a". Look through it again.

Also, for bonus points, implement a message decryption function without using "a" nor "b". 

Check out the modular multiplicative inverse. This is the equivalent of division modulo some number. Implementing it using the EEA can be tricky, though there is a shortcut.

Also, as Frob says, you have the wrong decryption function. You're trying to get "x" back, not "a". Look through it again.

Also, for bonus points, implement the decryption function without using "a" nor "b". 

Check out the modular multiplicative inverse. This is the equivalent of division modulo some number. Implementing it using the EEA can be tricky, though there is a shortcut.

Also, as Frob says, you have the wrong decryption function. You're trying to get "x" back, not "a". Look through it again.

Check out the modular multiplicative inverse. This is the equivalent of division modulo some number. Implementing it using the EEA can be tricky, though there is a shortcut.