use.std::math::ecgfp5::group

#! Generates the public key, point H
#! the private key is expected as input and is a 319-bit random
#! number of 10 32-bit limbs.
export.gen_privatekey.8
    exec.group::gen_mul
end

#! Given a random scalar r on stack
#! this routine computes the first elliptic curve point C_a
#! C_a = r*G, G is the generator of elliptic curve
#! Expected stack state
#! [r0, r1, ..., r9]
#! Final stack state
#! [Ca_x0, ..., C_x4, Ca_y0, ..., Ca_y4, Ca_inf]
export.encrypt_ca.8
    exec.group::gen_mul
end


#! Given public key, point H generated in gen_privatekey as coordinates (X,Y) on stack
#! and message M, elliptic curve points (a,b) also as coordinates (X,Y) on stack
#! and random scalar r on stack
#! this routine computes the second elliptic curve point C_b
#! C_b = M + r*H
#! Expected stack state
#! [H_x0, ..., H_x4, H_y0, ..., H_y4, H_inf, r0, r1, ..., M_x0, ..., M_x4, M_y0, ..., M_y4, M_inf,]
#! Final stack state
#! [Cb_x0, ..., Cb_x4, Cb_y0, ..., Cb_y4, Cb_inf]
export.encrypt_cb.20
    exec.group::mul
    exec.group::add
end

#! Rerandomises the first half of an ElGamal ciphertext Ca
#! and random scalar r to produce a rerandomised ciphertext C'a
#! Expected stack state
#! [r0, r1, ..., Ca_x0, ..., Ca_x4, Ca_y0, ..., Ca_y4, Ca_inf, ...]
#!
#! Final stack state
#! [C'a_x0, ..., C'a_x4, C'a_y0, ..., C'a_y4, C'a_inf]
export.remask_ca.5
    exec.group::gen_mul
    exec.group::add
end

#! Rerandomises the second half of an ElGamal ciphertext Cb given a public key H
#! and random scalar r to produce a rerandomised ciphertext C'b
#! Expected stack state
#! [H_x0, ..., H_x4, H_y0, ..., H_y4, H_inf, ..., r0, r1, ..., Cb_x0, ..., Cb_x4, Cb_y0, ..., Cb_y4, Cb_inf]
#!
#! Final stack state
#! [C'b_x0, ..., C'b_x4, C'b_y0, ..., C'b_y4, C'b_inf]
export.remask_cb.14
    exec.group::mul
    exec.group::add
end