moved some more files, used by cost_pairing.sage

BLS12.py

+import sage
+
+from exceptions import ValueError
+from sage.functions.log import log
+from sage.functions.other import ceil
+from sage.arith.misc import XGCD, xgcd
+from sage.rings.integer import Integer
+from sage.rings.finite_rings.finite_field_constructor import FiniteField
+from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
+from sage.schemes.elliptic_curves.ell_finite_field import EllipticCurve_finite_field
+from sage.schemes.elliptic_curves.constructor import EllipticCurve
+
+import PairingFriendlyCurve
+from PairingFriendlyCurve import get_curve_parameter_b_j0, get_curve_generator_order_r_j0
+
+
+class BLS12(EllipticCurve_finite_field):
+    """
+    A Barreto-Lynn-Scott curve of embedding degree 12
+    """
+    def __init__(self, u, b=None):
+        """
+        u is the seed such that p=P_BLS12(u), and b is the curve coefficient, s.t. y^2 = x^3 + b has a subgroup of order r=R_BLS12(u)
+        (there are two possible choices for b: b, 1/b (a twist) but only one has order r)
+        """
+        self._k = 12 # embedding degree
+        self._a = 0 # first curve parameter is 0 because j=0
+        self._D = 3
+        # polynomials (will be needed later for polynomial selection)
+        # P_BLS12 = (u-1)^2*(u^4 - u^2 + 1)/3 + u #= (s^6 - 2*s^5 + 2*s^3 + s + 1)/3
+        # R_BLS12 = u^4 - u^2 + 1
+        # C_BLS12 = (1/3) * (u - 1)^2 # cofactor such that p+1-tr == c*r
+        # T_BLS12 = u + 1
+        # Y_BLS12 = (u-1)*(2*u^2 - 1)/3 # = (2*s^3 - 2*s^2 - s + 1)/3
+        # Y such that T^2 - 4*P = -3*Y^2
+        # BETA_BLS12 = u^5 - 3*u^4 + 3*u^3 - u + 1
+        # LAMB_BLS12 = u^2 -1
+        # do not divides by 3 so that it has integer coeffs.
+        # pb type with 1/3 (as an int, it is 0) -> uses Integer(1)/Integer(3)
+        self.polynomial_p = [1, 1, 0, 2, 0, -2, 1]
+        self.polynomial_p_denom = 3
+        self.polynomial_r = [1, 0, -1, 0, 1]
+        self.polynomial_r_denom = 1
+        self.polynomial_c = [1, -2, 1]
+        self.polynomial_c_denom = 3
+        self.polynomial_tr = [1, 1]
+        self.polynomial_tr_denom = 1
+        self.polynomial_y = [1, -1, -2, 2]
+        self.polynomial_y_denom = 3
+        self.polynomial_beta = [1, -1, 0, 3, -3, 1]
+        self.polynomial_beta_denom = 1
+        self.polynomial_lamb = [-1, 0, 1]
+        self.polynomial_lamb_denom = 1
+
+        self._u = Integer(u)
+        self._p = (self._u-1)**2*(self._u**4 - self._u**2 + 1)//3 + self._u
+        self._pbits = self._p.nbits()
+        self._tr = self._u + 1
+        self._r = self._u**4 - self._u**2 + 1
+        self._c = (self._u-1)**2//3 # cofactor
+        if not self._c * self._r == self._p + 1 - self._tr:
+            raise ValueError("Error: r*c != p+1-tr\nr={}\nc={}\np+1-tr={}\n".format(self._r,self._c,self._p+1-self._tr))
+        self._y =  ((self._u - 1) * (2*self._u**2 - 1))//3
+        # GLV parameter for fast scalar multiplication thanks to automorphism
+        # psi: (x,y) -> (beta*x,y) = [lambda mod r]*(x,y) if (x,y) is of order r
+        # where beta is a root of x^2+x+1 mod p, beta = (-1 + sqrt(Fp(-3)))/2
+        # and lambda is a root of x^2+x+1 mod r, lamb = (-1 + sqrt(Fr(-3)))/2
+        # there are two choices: beta, -beta-1, and the same for lamb: lamb, -lamb-1
+        # arbitrarily the positive ones are chosen
+        self._beta = self._u**5 - 3*self._u**4 + 3*self._u**3 - self._u + 1
+        self._lamb = self._u**2 - 1
+        try:
+            self._Fp = FiniteField(self._p)
+        except ValueError as err:
+            print("ValueError creating Fp: {}".format(err))
+            raise
+        except:
+            print("Error creating Fp")
+            raise
+        if not self._r.is_prime():
+            raise ValueError("Error r is not prime")
+
+        if ((self._beta**2 + self._beta + 1) % self._p) != 0:
+            raise ValueError("Error beta^2 + beta + 1 != 0 mod p")
+        if ((self._lamb**2 + self._lamb + 1) % self._r) != 0:
+            raise ValueError("Error lamb^2 + lamb + 1 != 0 mod r")
+        
+        self._Fpz = PolynomialRing(self._Fp, names=('z',))
+        (self._z,) = self._Fpz._first_ngens(1)
+
+        if b != None:
+            try:
+                b = Integer(b)
+            except:
+                raise
+            self._b = b
+            self._bp = self._Fp(b)
+        else:
+            # check that beta = 2*U/(-3*V-U) before, where U=t/2, V = y/2 and 2V = 2 mod 3
+            self._b, self._bp = get_curve_parameter_b_j0(self._tr, self._y, self._beta, self._p, self._Fp)
+        self._ap = self._Fp(0) # first curve parameter is 0 because j=0
+        # Now self._b is such that E: y^2 = x^3 + b has order r
+        try:
+            # this init function of super inherits from class EllipticCurve_generic defined in ell_generic.py
+            # __init__ method inherited from ell_generic
+            EllipticCurve_finite_field.__init__(self, self._Fp, [0,0,0,0,self._bp])
+        except ValueError as err:
+            print("ValueError at EllipticCurve_finite_field.__init__: {}".format(err))
+            raise
+        except:
+            print("An error occupred when initialising the elliptic curve")
+            raise
+        self.order_checked = super(BLS12,self).order()
+        if self.order_checked != (self._p+1-self._tr):
+            print("Error, wrong order")
+            raise ValueError("Wrong curve order: this one is a twist")
+
+        # computes a generator
+        self._G = get_curve_generator_order_r_j0(self)
+        self._Gx = self._G[0]
+        self._Gy = self._G[1]
+        
+        # adjust beta and lamb according to the curve
+        # do we have (beta*x,y) = lamb*(x,y)?
+        if self([self._Gx*self._beta, self._Gy]) != self._lamb*self._G:
+            print("adjusting beta, lambda")
+            if self([self._Gx*(-self._beta-1), self._Gy]) == self._lamb*self._G:
+                self._beta = -self._beta-1
+                print("beta -> -beta-1")
+            elif self([self._Gx*self._beta, self._Gy]) == (-self._lamb-1)*self._G:
+                self._lamb = -self._lamb-1
+                print("lamb -> -lamb-1")
+            elif self([self._Gx*(-self._beta-1), self._Gy]) == (-self._lamb-1)*self._G:
+                self._beta = -self._beta-1
+                self._lamb = -self._lamb-1
+                print("lamb -> -lamb-1")
+                print("beta -> -beta-1")
+            else:
+                raise ValueError("Error while adjusting beta, lamb: compatibility not found")
+
+    def _repr_(self):
+        return "BLS12 p"+str(self._pbits)+" (Barreto-Lynn-Scott k=12) curve with seed "+str(self._u)+"\n"+super(BLS12,self)._repr_()
+
+    def u(self):
+        return self._u
+    def p(self):
+        return self._p
+    def r(self):
+        return self._r
+    def c(self):
+        return self._c
+    def tr(self):
+        return self._tr
+    def y(self):
+        return self._y
+    def a(self):
+        return self._a # 0
+    def ap(self):
+        return self._ap # 0
+    def b(self):
+        return self._b # Integer
+    def bp(self):
+        return self._bp # in Fp (finite field element)
+    def beta(self):
+        return self._beta
+    def lamb(self):
+        return self._lamb
+    
+    def k(self):
+        return self._k
+    def Fp(self):
+        return self._Fp
+    def Fpz(self):
+        return self._Fpz, self._z
+    def G(self):
+        return self._G
+
+    def print_parameters(self):
+        PairingFriendlyCurve.print_parameters(self)
+        
+    def print_parameters_for_RELIC(self):
+        PairingFriendlyCurve.print_parameters_for_RELIC(self)
+

BN.py

+# http://doc.sagemath.org/html/en/thematic_tutorials/tutorial-objects-and-classes.html
+# http://doc.sagemath.org/html/en/thematic_tutorials/coercion_and_categories.html
+# http://doc.sagemath.org/html/en/thematic_tutorials/tutorial-implementing-algebraic-structures.html
+# https://docs.python.org/3/library/functions.html#super
+# https://rhettinger.wordpress.com/2011/05/26/super-considered-super/
+
+import sage
+
+from exceptions import ValueError
+from sage.functions.log import log
+from sage.functions.other import ceil
+from sage.arith.misc import XGCD, xgcd
+from sage.rings.integer import Integer
+from sage.rings.finite_rings.finite_field_constructor import FiniteField
+from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
+#from sage.schemes.elliptic_curves.ell_generic import EllipticCurve_generic
+#from sage.schemes.elliptic_curves.ell_field import EllipticCurve_field
+from sage.schemes.elliptic_curves.ell_finite_field import EllipticCurve_finite_field
+from sage.schemes.elliptic_curves.constructor import EllipticCurve
+
+import PairingFriendlyCurve
+from PairingFriendlyCurve import get_curve_parameter_b_j0, get_curve_generator_order_r_j0
+
+
+class BN(EllipticCurve_finite_field):
+    """
+    A Barreto-Naehrig curve
+    """
+    def __init__(self, u, b=None):
+        """
+        u is the seed such that p=P_BN(u), and b is the curve coefficient, s.t. y^2 = x^3 + b has exactly order r=R_BN(u)
+        (there are two possible choices for b: b, 1/b (a twist) but only one has order r)
+        """
+        self._k = 12 # embedding degree
+        self._a = 0 # first curve parameter is 0 because j=0
+        self._D = 3
+        # polynomials (will be needed later for polynomial selection)
+        # P_BN = 36*u^4 + 36*u^3 + 24*u^2 + 6*u + 1
+        # R_BN = 36*u^4 + 36*u^3 + 18*u^2 + 6*u + 1
+        # C_BN = 1 # cofactor such that p+1-tr == c*r
+        # T_BN = 6*u^2 + 1
+        # Y_BN = 6*u^2 + 4*u + 1 # such that T_BN^2 - 4*P_BN = -3*Y_BN^2
+        # BETA_BN = 18*u^3 + 18*u^2 + 9*u + 1
+        # LAMB_BN = 36*u^3 + 18*u^2 + 6*u + 1
+        self.polynomial_p = [1,6,24,36,36]
+        self.polynomial_r = [1,6,18,36,36]
+        self.polynomial_c = [1]
+        self.polynomial_tr= [1,0,6]
+        self.polynomial_y = [1,4,6]
+        self.polynomial_beta = [1,9,18,18]
+        self.polynomial_lamb = [1,6,18,36]
+        
+        self._u = Integer(u)
+        self._p = 36*self._u**4 + 36*self._u**3 + 24*self._u**2 + 6*self._u + 1
+        self._pbits = self._p.nbits()
+        self._tr = 6*self._u**2 + 1
+        self._r = 36*self._u**4 + 36*self._u**3 + 18*self._u**2 + 6*self._u + 1
+        self._c = Integer(1)
+        self._y = 6*self._u**2 + 4*self._u + 1 # such that T^2 - 4*P = -3*Y^2
+        # GLV parameter for fast scalar multiplication thanks to automorphism
+        # psi: (x,y) -> (beta*x,y) = [lambda mod r]*(x,y) if (x,y) is of order r
+        # where beta is a root of x^2+x+1 mod p, beta = (-1 +/- sqrt(Fp(-3)))/2
+        # beta = 18*u^3 + 18*u^2 + 9*u + 1 (other one is -beta-1)
+        # and lambda is a root of x^2+x+1 mod r, lamb = (-1 +/- sqrt(Fr(-3)))/2
+        # lamb = 36*u^3 + 18*u^2 + 6*u + 1 (other one is -lamb-1)
+        # there are two choices: beta, -beta-1, and the same for lamb: lamb, -lamb-1
+        # arbitrarily the positive ones are chosen
+        self._beta = 18*self._u**3 + 18*self._u**2 + 9*self._u + 1
+        self._lamb = 36*self._u**3 + 18*self._u**2 + 6*self._u + 1
+        try:
+            self._Fp = FiniteField(self._p)
+        except ValueError as err:
+            print("ValueError creating Fp: {}".format(err))
+            raise
+        except:
+            print("Error creating Fp")
+            raise
+        if not self._r.is_prime():
+            raise ValueError("Error r is not prime")
+        
+        if ((self._beta**2 + self._beta + 1) % self._p) != 0:
+            raise ValueError("Error beta^2 + beta + 1 != 0 mod p")
+        if ((self._lamb**2 + self._lamb + 1) % self._r) != 0:
+            raise ValueError("Error lamb^2 + lamb + 1 != 0 mod r")
+        
+        self._Fpz = PolynomialRing(self._Fp, names=('z',))
+        (self._z,) = self._Fpz._first_ngens(1)
+        
+        if b != None:
+            try:
+                b = Integer(b)
+            except:
+                raise
+            self._b = b
+            self._bp = self._Fp(b)
+        else:
+            # BN curves:
+            # Pereira et al solution: b = c^4 + d^6 or b = c^6 + 4*d^4 for c, d in Fp*
+            # https://eprint.iacr.org/2010/429
+            self._b, self._bp = get_curve_parameter_b_j0(self._tr, self._y, self._beta, self._p, self._Fp)
+        self._ap = self._Fp(0) # first curve parameter is 0 because j=0
+        # Now self._b is such that E: y^2 = x^3 + b has order r
+        try:
+            # this init function of super inherits from class EllipticCurve_generic defined in ell_generic.py
+            # __init__ method inherited from ell_generic
+            EllipticCurve_finite_field.__init__(self, self._Fp, [0,0,0,0,self._bp])
+        except ValueError as err:
+            print("ValueError at EllipticCurve_finite_field.__init__: {}".format(err))
+            raise
+        except:
+            print("An error occupred when initialising the elliptic curve")
+            raise
+        self.order_checked = super(BN,self).order()
+        if self.order_checked != self._r:
+            print("Error, wrong order")
+            raise ValueError("Wrong curve order: this one is a twist")
+
+        # computes a generator
+        self._G = get_curve_generator_order_r_j0(self)
+        self._Gx = self._G[0]
+        self._Gy = self._G[1]
+        # note that there is no cofactor for BN curves because r=p+1-tr
+        
+        # adjust beta and lamb according to the curve
+        # do we have (beta*x,y) = lamb*(x,y)?
+        if self([self._Gx*self._beta, self._Gy]) != self._lamb*self._G:
+            print("adjusting beta, lambda")
+            if self([self._Gx*(-self._beta-1), self._Gy]) == self._lamb*self._G:
+                self._beta = -self._beta-1
+                print("beta -> -beta-1")
+            elif self([self._Gx*self._beta, self._Gy]) == (-self._lamb-1)*self._G:
+                self._lamb = -self._lamb-1
+                print("lamb -> -lamb-1")
+            elif self([self._Gx*(-self._beta-1), self._Gy]) == (-self._lamb-1)*self._G:
+                self._beta = -self._beta-1
+                self._lamb = -self._lamb-1
+                print("lamb -> -lamb-1")
+                print("beta -> -beta-1")
+            else:
+                raise ValueError("Error while adjusting beta, lamb: compatibility not found")
+    
+    def _repr_(self):
+        return "BN p"+str(self._pbits)+" (Barreto-Naehrig) curve with seed "+str(self._u)+"\n"+super(BN,self)._repr_()
+
+    def u(self):
+        return self._u
+    def p(self):
+        return self._p
+    def r(self):
+        return self._r
+    def c(self):
+        return self._c # cofactor is Integer(1) because r=p+1-tr and r is prime
+    def tr(self):
+        return self._tr
+    def y(self):
+        return self._y
+    def a(self):
+        return self._a # 0
+    def ap(self):
+        return self._ap # 0
+    def b(self):
+        return self._b # Integer
+    def bp(self):
+        return self._bp # in Fp (finite field element)
+    def beta(self):
+        return self._beta
+    def lamb(self):
+        return self._lamb
+    
+    def k(self):
+        return self._k
+    def Fp(self):
+        return self._Fp
+    def Fpz(self):
+        return self._Fpz, self._z
+    def G(self):
+        return self._G
+
+    def print_parameters(self):
+        PairingFriendlyCurve.print_parameters(self)
+
+    def print_parameters_for_RELIC(self):
+        PairingFriendlyCurve.print_parameters_for_RELIC(self)
+
+

KSS16.py

+import sage
+
+from exceptions import ValueError
+from sage.functions.log import log
+from sage.functions.other import ceil
+from sage.arith.misc import XGCD, xgcd
+from sage.rings.integer import Integer
+from sage.rings.finite_rings.finite_field_constructor import FiniteField
+from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
+from sage.schemes.elliptic_curves.ell_finite_field import EllipticCurve_finite_field
+from sage.schemes.elliptic_curves.constructor import EllipticCurve
+
+import PairingFriendlyCurve
+from PairingFriendlyCurve import get_curve_parameter_a_j1728, get_curve_generator_order_r_j1728
+
+
+class KSS16(EllipticCurve_finite_field):
+    """
+    A Kachisa-Schaefer-Scott curve of embedding degree 16
+    """
+    def __init__(self, u, a=None):
+        """
+        u is the seed such that p=P_KSS16(u), and a is the curve coefficient, s.t. y^2 = x^3 + a*x has a subgroup of order r=R_KSS16(u)
+        (there are two possible choices for a: a, 1/a (a twist) but only one has order r)
+        """
+        self._k = 16 # embedding degree
+        self._b = 0 # second curve parameter is 0 because j=1728
+        self._D = 4 # 4, not 1, be careful with that
+        # polynomials (will be needed later for polynomial selection)
+        # P_KSS16 = (s^10 + 2*s^9 + 5*s^8 + 48*s^6 + 152*s^5 + 240*s^4 + 625*s^2 + 2398*s + 3125)/980
+        # R_KSS16 = (s^8 + 48*s^4 + 625)/61250 # 625 = 5^4, 61250 = 2*5^4*7^2
+        # T_KSS16 = (2*s^5 + 41*s + 35)/35
+        # C_KSS16 = (125/2) * (s^2 + 2*s + 5) # C such that P+1-T = C*R
+        # Y_KSS16 =  (1/70) * (s^5 + 5*s^4 + 38*s + 120) # Y such that T^2 - 4*P = -3*Y^2
+        # assert (P_KSS16+1-T_KSS16) == C_KSS16*R_KSS16
+        # assert (T_KSS16^2 + D_KSS16*Y_KSS16^2)/4 == P_KSS16
+        # sqrt(-1) mod P
+        # BETA_KSS16 = (s^9-11*s^8-16*s^7-120*s^6-32*s^5-498*s^4-748*s^3-2740*s^2-3115*s-5651)/4018
+        # LAMB_KSS16 = (1/7)*(s^4 + 24) # sqrt(-1) mod R
+        self.polynomial_p = [3125, 2398, 625, 0, 240, 152, 48, 0, 5, 2, 1]
+        self.polynomial_p_denom = 980
+        self.polynomial_r = [625, 0, 0, 0, 48, 0, 0, 0, 1]
+        self.polynomial_r_denom = 61250
+        # when u = 25, 45 mod 70, then P(u), T(u), (P+1-T)(u) are all integers, and 61250 | R(u)
+        self.polynomial_c = [625, 250, 125]
+        self.polynomial_c_denom = 2
+        self.polynomial_tr= [35, 41, 0, 0, 0, 2]
+        self.polynomial_tr_denom= 35 # we need u = 25,45 mod 70 for T to be integer
+        self.polynomial_y = [120, 38, 0, 0, 5, 1]
+        self.polynomial_y_denom = 70
+        self.polynomial_beta = [-5651, -3115, -2740, -748, -498, -32, -120, -16, -11, 1]
+        self.polynomial_beta_denom = 4018 # 2 * 7^2 * 41
+        self.polynomial_lamb = [24, 0, 0, 0, 1]
+        self.polynomial_lamb_denom = 7
+
+        self._u = Integer(u)
+        self._p = sum([Integer(self.polynomial_p[i])*self._u**i for i in range(len(self.polynomial_p))])//self.polynomial_p_denom
+        self._pbits = self._p.nbits()
+        self._r = sum([Integer(self.polynomial_r[i])*self._u**i for i in range(len(self.polynomial_r))])//self.polynomial_r_denom
+        self._c = sum([Integer(self.polynomial_c[i])*self._u**i for i in range(len(self.polynomial_c))])//self.polynomial_c_denom
+        self._tr= sum([Integer(self.polynomial_tr[i])*self._u**i for i in range(len(self.polynomial_tr))])//self.polynomial_tr_denom
+        if not self._c * self._r == self._p + 1 - self._tr:
+            raise ValueError("Error: r*c != p+1-tr\nr={}\nc={}\np+1-tr={}\n".format(self._r,self._c,self._p+1-self._tr))
+        self._y = sum([Integer(self.polynomial_y[i])*self._u**i for i in range(len(self.polynomial_y))])//self.polynomial_y_denom
+        # GLV parameter for fast scalar multiplication thanks to automorphism
+        # psi: (x,y) -> (-x,i*y) = [lambda mod r]*(x,y) if (x,y) is of order r
+        # where beta is a root of x^2+1 mod p, beta = sqrt(-1) mod p
+        # and lambda is a root of x^2+1 mod r, lamb = sqrt(-1) mod r
+        # there are two choices: beta, -beta, and the same for lamb: lamb, -lamb
+        # arbitrarily the positive ones are chosen
+        # unfortunately beta has always denominator 41, computes modulo p: / instead of //
+        self._beta = sum([Integer(self.polynomial_beta[i])*self._u**i for i in range(len(self.polynomial_beta))])/Integer(self.polynomial_beta_denom)
+        # LAMB is an integer when u=25,45 mod 70, which should be the case for P, T, R to be integers.
+        self._lamb = sum([Integer(self.polynomial_lamb[i])*self._u**i for i in range(len(self.polynomial_lamb))])//self.polynomial_lamb_denom
+        try:
+            self._Fp = FiniteField(self._p)
+        except ValueError as err:
+            print("ValueError creating Fp: {}".format(err))
+            raise
+        except:
+            print("Error creating Fp")
+            raise
+        if not self._r.is_prime():
+            raise ValueError("Error r is not prime")
+
+        # beta has denominator 41, reduces mod p:
+        self._beta = Integer(self._Fp(self._beta))
+        if ((self._beta**2 + 1) % self._p) != 0:
+            raise ValueError("Error beta^2 + 1 != 0 mod p")
+        if ((self._lamb**2 + 1) % self._r) != 0:
+            raise ValueError("Error lamb^2 + 1 != 0 mod r")
+        
+        self._Fpz = PolynomialRing(self._Fp, names=('z',))
+        (self._z,) = self._Fpz._first_ngens(1)
+
+        self._bp = self._Fp(0) # second curve parameter is 0 because j=1728
+        if a != None:
+            try:
+                a = Integer(a)
+            except:
+                raise
+            self._a = a
+            self._ap = self._Fp(a)
+        else:
+            # check that beta = U/V, where U=t/2, V = y
+            self._a, self._ap = get_curve_parameter_a_j1728(self._tr, self._y, self._beta, self._p, self._Fp)
+        # Now self._a is such that E: y^2 = x^3 + a*x has order r
+        try:
+            # this init function of super inherits from class EllipticCurve_generic defined in ell_generic.py
+            # __init__ method inherited from ell_generic
+            EllipticCurve_finite_field.__init__(self, self._Fp, [0,0,0,self._ap,0])
+        except ValueError as err:
+            print("ValueError at EllipticCurve_finite_field.__init__: {}".format(err))
+            raise
+        except:
+            print("An error occupred when initialising the elliptic curve")
+            raise
+        self.order_checked = super(KSS16,self).order()
+        if self.order_checked != (self._p+1-self._tr):
+            print("Error, wrong order")
+            raise ValueError("Wrong curve order: this one is a twist")
+
+        # computes a generator
+        self._G = get_curve_generator_order_r_j1728(self)
+        self._Gx = self._G[0]
+        self._Gy = self._G[1]
+        
+        # adjust beta and lamb according to the curve
+        # do we have (-x,beta*y) = lamb*(x,y)?
+        if self([-self._Gx, self._Gy*self._beta]) != self._lamb*self._G:
+            print("adjusting beta, lambda")
+            if self([-self._Gx, self._Gy*(-self._beta)]) == self._lamb*self._G:
+                self._beta = self._p-self._beta
+                print("beta -> -beta")
+            elif self([-self._Gx, self._Gy*self._beta]) == (-self._lamb)*self._G:
+                self._lamb = -self._lamb
+                print("lamb -> -lamb")
+            elif self([-self._Gx, self._Gy*(-self._beta)]) == (-self._lamb)*self._G:
+                self._beta = self._p-self._beta
+                self._lamb = -self._lamb
+                print("lamb -> -lamb")
+                print("beta -> -beta")
+            else:
+                raise ValueError("Error while adjusting beta, lamb: compatibility not found")
+
+    def _repr_(self):
+        return "KSS16 p"+str(self._pbits)+" (Kachisa-Schaefer-Scott k=16) curve with seed "+str(self._u)+"\n"+super(KSS16,self)._repr_()
+
+    def u(self):
+        return self._u
+    def p(self):
+        return self._p
+    def r(self):
+        return self._r
+    def c(self):
+        return self._c
+    def tr(self):
+        return self._tr
+    def y(self):
+        return self._y
+    def a(self):
+        return self._a # Integer
+    def ap(self):
+        return self._ap # in Fp (finite field element)
+    def b(self):
+        return self._b # 0
+    def bp(self):
+        return self._bp # 0
+    def beta(self):
+        return self._beta
+    def lamb(self):
+        return self._lamb
+    
+    def k(self):
+        return self._k
+    def Fp(self):
+        return self._Fp
+    def Fpz(self):
+        return self._Fpz, self._z
+    def G(self):
+        return self._G
+
+    def print_parameters(self):
+        PairingFriendlyCurve.print_parameters(self)
+        
+    def print_parameters_for_RELIC(self):
+        PairingFriendlyCurve.print_parameters_for_RELIC(self)
+

MNT6.py

+# MNT curves with k=6
+# This time, j != 0.
+import sage
+
+from exceptions import ValueError
+from sage.functions.log import log
+from sage.functions.other import ceil
+from sage.functions.other import sqrt
+from sage.arith.misc import XGCD, xgcd
+from sage.rings.integer import Integer
+from sage.rings.finite_rings.finite_field_constructor import FiniteField
+from sage.rings.polynomial.polynomial_ring_constructor import PolynomialRing
+from sage.schemes.elliptic_curves.ell_finite_field import EllipticCurve_finite_field
+from sage.schemes.elliptic_curves.constructor import EllipticCurve
+
+import PairingFriendlyCurve
+from PairingFriendlyCurve import get_curve_generator_order_r
+
+class MNT6(EllipticCurve_finite_field):
+    """
+    A Miyaji-Nakabayashi-Takano curve of embedding degree 6
+    http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.20.8113&rep=rep1&type=pdf
+    """
+    def __init__(self, u, a, b, D=None, c=None):
+        """
+        u is the seed such that p=P_MNT6(u), and a,b are the curve coefficients, 
+        s.t. y^2 = x^3 + a*x + b has exactly order r=R_MNT6(u)
+        (there are two possible choices for b: b, 1/b (a twist) but only one has order r)
+        """
+        self._k = 6 # embedding degree
+        self._a = Integer(a)
+        self._b = Integer(b)
+        if D != None:
+            self._D = Integer(D)
+        # polynomials (will be needed later for polynomial selection)
+        #P_MNT6 = 4*x^2+1
+        #R_MNT6 = 4*x^2 - 2*x + 1
+        #C_MNT6 = 1
+        #T_MNT6 = 2*x + 1
+        #DY2_MNT6 = 12*x^2 - 4*x + 3
+        # no beta, lambda
+        self.polynomial_p = [1, 0, 4]
+        self.polynomial_p_denom = 1
+        self.polynomial_r = [1, -2, 4]
+        self.polynomial_r_denom = 1
+        self.polynomial_c = [1]
+        self.polynomial_c_denom = 1
+        self.polynomial_tr = [1, 2]
+        self.polynomial_tr_denom = 1
+
+        self._u = Integer(u)
+        self._p = Integer(4)*(self._u)**2 + Integer(1)
+        self._pbits = self._p.nbits()
+        self._tr = Integer(2)*self._u + 1
+        self._r = Integer(4)*self._u**2 - Integer(2)*self._u + 1
+        if c != None and c != 1 and (self._r % Integer(c)) == 0:
+            self._c = Integer(c)
+            self._r = self._r // self._c
+        else:
+            self._c = Integer(1)
+        if not self._c * self._r == self._p + 1 - self._tr:
+            raise ValueError("Error: r*c != p+1-tr\nr={}\nc={}\np+1-tr={}\n".format(self._r,self._c,self._p+1-self._tr))
+        #print("computing y")
+        self._y = Integer(((4*self._p - self._tr**2)//self._D).sqrt())
+        #print("y done")
+
+        try:
+            self._Fp = FiniteField(self._p)
+        except ValueError as err:
+            print("ValueError creating Fp: {}".format(err))
+            raise
+        except:
+            print("Error creating Fp")
+            raise
+        if not self._r.is_prime():
+            raise ValueError("Error r is not prime")
+
+        self._Fpz = PolynomialRing(self._Fp, names=('z',))
+        (self._z,) = self._Fpz._first_ngens(1)
+
+        if a != None:
+            try:
+                a = Integer(a)
+            except:
+                raise
+            self._a = a
+            self._ap = self._Fp(a)
+        if b != None:
+            try:
+                b = Integer(b)
+            except:
+                raise
+            self._b = b
+            self._bp = self._Fp(b)
+
+        try:
+            # this init function of super inherits from class EllipticCurve_generic defined in ell_generic.py
+            # __init__ method inherited from ell_generic
+            EllipticCurve_finite_field.__init__(self, self._Fp, [0,0,0,self._ap,self._bp])
+        except ValueError as err:
+            print("ValueError at EllipticCurve_finite_field.__init__: {}".format(err))
+            raise
+        except:
+            print("An error occupred when initialising the elliptic curve")
+            raise
+        #print("check order")
+        #self.order_checked = super(MNT6,self).order()
+        #if self.order_checked != (self._p+1-self._tr):
+        #    raise ValueError("Wrong curve order: this one is a twist")
+        print("check order (randomized)")
+        self.curve_order = self._p + Integer(1) - self._tr
+        self.twist_order = self._p + Integer(1) + self._tr
+        for i in range(10):
+            P = self.random_element()
+            if self.curve_order*P != self(0):
+                if self.twist_order*P == self(0):
+                    raise ValueError("Wrong curve order: this one is a twist: (p+1+tr)*P = 0\ntr={}\nr={}\np+1+tr={}\n".format(self._tr,self.curve_order,self.twist_order))
+                else:
+                    self.order_checked = super(MNT6,self).order()
+                    raise ValueError("Wrong curve order:\np+1-tr        = {}\np+1+tr        = {}\nchecked order = {}\np             = {}".format(self.curve_order,self.twist_order,self.order_checked,self._p))
+        print("ok")
+        
+        # computes a generator
+        self._G = get_curve_generator_order_r(self)
+        self._Gx = self._G[0]
+        self._Gy = self._G[1]
+
+    def _repr_(self):
+        return "MNT6 p"+str(self._pbits)+" (Miyaji-Nakabayashi-Takano curve k=6) curve with seed "+str(self._u)+"\n"+super(MNT6,self)._repr_()
+
+    def u(self):
+        return self._u
+    def p(self):
+        return self._p
+    def r(self):
+        return self._r
+    def c(self):
+        return self._c
+    def tr(self):
+        return self._tr
+    def y(self):
+        return self._y
+    def a(self):
+        return self._a # 0
+    def ap(self):