Bignum bigmul(Bignum a, Bignum b);
Bignum modinv(Bignum number, Bignum modulus);
Bignum bignum_rshift(Bignum number, int shift);
Bignum bigmul(Bignum a, Bignum b);
Bignum modinv(Bignum number, Bignum modulus);
Bignum bignum_rshift(Bignum number, int shift);