#! /usr/bin/python
# code =gbk
Import mathematics
Def quick _ algorithm (a, b, c): # y = a b% c, and the b power of a is divided by C.
a = a % c
ans = 1
# We don't need to think about B.
And b! = 0: # Fermat Theorem
If b & kloc-0/:
ans = (ans * a) % c
b & gt& gt= 1
a = (a * a) % c
Return the answer
Def IsHaveMoSqrt(x, P):# Whether there is a modular square root y*y=x mod p, given x, p, judge whether there is y..
ret = quick_algorithm(x，(P- 1)//2，P)
If ret== 1:
Return True
Otherwise:
Returns False
Def GetMoSqrt(x, P):# Find the square root of module y*y=x mod p, where x is known and p finds y.
if(IsHaveMoSqrt(x，P)== 1):
t=0
S = p-1# p-1= (2t) * s//s is an odd number.
And s%2==0:
s=s//2
t=t+ 1
if(t== 1):
ret = quick_algorithm(x，(s+ 1)//2，P)
Return (ret, P-ret)
elif(t & gt； =2):
X _ = fast algorithm (x, P-2, p)
n= 1
while(IsHaveMoSqrt(n，P)== 1):
n=n+ 1
B = fast algorithm (n, s, p)
Print (b)
ret = quick_algorithm(x，(s+ 1)//2，P)#t- 1
t_=0
while(t- 1 & gt； 0):
if(quick_algorithm(x_*ret*ret，2**(t-2)，P)== 1):
Ret = return
Otherwise:
ret = ret *(b * *(2 * * t _)% P
t=t- 1
t_=t_+ 1
Return (ret, P-ret)
Otherwise:
Return (-2, -2)
Otherwise:
Returns (-1,-1)
Defsecp256k1getybyx (x): # y 2 = x 3+7 (mod p) Find y according to x.
a =(x * x * x+7)% 0x fffffffffffffffffffffffffffffffffffffffffffffff 2f
ret = GetMoSqrt(a，0x fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff 2f)
Return to ret
if __name__ == "__main__ ":
If true:
X = 0x79be667E9DCBBa55A 06295ce870b07029bfcdb2dce28d959f28 1 5b1798 # The private key is1,and the corresponding public key is X.
Ret = secp256k1getybyx (x) # secp256k1,and find y according to x.
print("x=%x" % (x))
print("y=%x" % (ret[0]))
print("y=%x" % (ret[ 1]))
Print ("")
X= 1#x minimum value
Ret = secp256k1getybyx (x) # secp256k1,and find y according to x.
print("x=%x" % (x))
print("y=%x" % (ret[0]))
print("y=%x" % (ret[ 1]))
Print ("")
X = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF C2F-3 # x Maximum value.
Ret = secp256k1getybyx (x) # secp256k1,and find y according to x.
print("x=%x" % (x))
print("y=%x" % (ret[0]))
print("y=%x" % (ret[ 1]))
Print ("")
Enter ()
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