stigid(V,b)=subst(Pol(V),'x,b);		\\ inverse function digits(...)

n = 9516311845790656153499716760847001433441357;
e = 65537;
d = 5617843187844953170308463622230283376298685;

text = "Rosetta Code"

inttext = stigid(Vecsmall(text),256)	\\ message as an integer
encoded = lift(Mod(inttext, n) ^ e)	\\ encrypted message
decoded = lift(Mod(encoded, n) ^ d)	\\ decrypted message
message = Strchr(digits(decoded, 256))	\\ readable message