# RSA暗号の例
import random
import fractions
import sympy
import warnings 
warnings.filterwarnings('ignore')

# 乱数生成
def _random():
    digit = 10
    return random.randrange(10**(digit - 1),10**digit)

# 最小公倍数
def _lcm(p , q):
    return (p * q) // fractions.gcd(p, q)

# 拡張ユークリッド
def _euclid(x,y):
    c0, c1 = x, y
    a0, a1 = 1, 0
    b0, b1 = 0, 1
    while c1 != 0:
        m = c0 % c1
        q = c0 // c1
        c0, c1 = c1, m
        a0, a1 = a1, (a0 - q * a1)
        b0, b1 = b1, (b0 - q * b1)
    return c0, a0, b0

# キー生成
def generate_key(p = 0,q = 0,e = 0,d = 0,n = 0,l = 0):
    if p == 0:
        while True:
            p = _random()
            if sympy.isprime(p):break
    _p = p
    if q == 0:
        while True:
            q = _random()
            if sympy.isprime(q) and p != q:break
    _q = q
    if n == 0:
        n = p * q
    _n = n
    if l == 0:
        l = _lcm(p - 1, q  - 1)
    _l = l
    if e == 0:
        while True:
            i = random.randint(2,l)
            if fractions.gcd(i, l) == 1:
                e = i
                break
    _e = e
    if d == 0:
        _c, a, _b = _euclid(e, l)
        d = a % l
    _d = d
    return _e,_d,_n,_p,_q,_l

# 暗号化
def encrypt(_e,_n,plaintext):
    st,ciphertext = "",[]
    for i in map((lambda x: pow(ord(x), _e,_n)),list(plaintext)):
        ciphertext.append(i)
        st += str(i)
    return st,ciphertext

# 復号化
def decrypt(_d,_n,ciphertext):
    cip , st = [] , ""
    for i in  list(ciphertext):
        tmp = chr(pow(i, _d,_n))
        cip.append(tmp)
        st += str(tmp)
    return st

plain_text = '文字列を入力'

# 初期化
ciphertext = []
_e = _d = _n = _p = _q = _l = 0

# キー生成
_e,_d,_n,_p,_q,_l = generate_key(0,0,65537)

# 暗号化
e_text , ciphertext = encrypt(_e,_n,plain_text)

# 復号化
d_text = decrypt(_d,_n,ciphertext)

print('素数 p : {0}'.format(_p))
print('素数 q : {0}'.format(_q))
print('l : {0}'.format(_l))
print('公開鍵 e : {0}'.format(_e))
print('公開鍵 n : {0}'.format(_n))
print('秘密鍵 d : {0}'.format(_d))
print()

print('暗号文(String) : {0}'.format(e_text))
print()
print('暗号文(List) : {0}'.format(ciphertext))

タグ ：

Python

プログラミング

暗号

RSA

アルゴリズム