@classmethod
def parse(self, sec_bin):
if sec_bin[0] == 4:
x = int.from_bytes(sec_bin[1:33], 'big')
y = int.from_bytes(sec_bin[33:65], 'big')
return S256Point(x=x, y=y)
is_even = sec_bin[0] == 2
x = S256Field(int.from_bytes(sec_bin[1:], 'big'))
alpha = x**3 + S256Field(B)
beta = alpha.sqrt()
if beta.num % 2 == 0:
even_beta = beta
odd_beta = S256Field(P - beta.num)
else:
even_beta = S256Field(P - beta.num)
odd_beta = beta
if is_even:
return S256Point(x, even_beta)
else:
return S256Point(x, odd_beta)
公開鍵が04, 03, 02かで秘密鍵の点を戻す
SEC圧縮フォーマットは以下の通り
from ecc import S256Point, PrivateKey p = PrivateKey(5001) print(p.point.sec(compressed=True).hex())
