def ccs_dec(c0, c1, c2, g, h, h1, x1):
''' Decryption for CCS Cryptosystem '''
basis = pairing(g, h1)
ct = pairing(c0 * x1 + ~c1, h) + pairing(g, c2)
# Addition ou multiplication entre les deux pairings ?
# TODO addition j'espère car sinon faut implémenter * dans F_12 :S
m = __dlog(ct, basis)
return m
def ccs_open(m, a, c2, g, h, h1):
if pairing(a, h) == pairing(g, c2 + ~(h1 * m)):
return m
else:
return None
