纯手写实现Des加密和解密的过程，没用到其他第三方库。

能处理16个16进制数(64bit)组成的明文和16个16进制数(64bit)组成的密钥的进行的加密解密。

可自行对明文分组(64bit一组)以处理更多的更长的明文加密。

secret_key = []


def change_hex_to_bin(s):
    a = bin(int(s, 16))[2:].upper().rjust(64, '0')
    return a


def xor(left, right):
    result = int(left, 2) ^ int(right, 2)
    return bin(result)[2:].rjust(len(left), '0')


def translation(s, list_1):
    result = ''
    for i in list_1:
        result += s[i-1]
    return result


def move(lst, k):
    k *= -1
    len2 = len(lst)
    ss = (lst[k:]+lst[:k]).rjust(len2, '0')
    return str(ss)


def func_f(right, key):
    result = translation(right, table_e)
    result = xor(str(result), str(key))
    result2 = ''
    for i in range(0, len(result)-5, 6):
        j = i // 6
        r = int(result[i] + result[i + 5], 2)
        n = int(result[i + 1] + result[i + 2] + result[i + 3] + result[i + 4], 2)
        d = s_box[j][r * 16 + n]
        result2 += bin(d)[2:].upper().rjust(4, '0')
    result = translation(result2, table_p)
    return str(result)


def generate_secret(key_left, key_right):
    key_left = move(key_left, -1)
    key_right = move(key_right, -1)
    key = translation(key_left + key_right, pc2)
    secret_key.append(key)
    return key_left, key_right, key


def wheel_structure(left, right, key_left, key_right, r, ty):
    for i in range(0, r):
        if ty == 1:
            key_left, key_right, key = generate_secret(key_left, key_right)
        else:
            key = secret_key[-1]
            secret_key.pop()
        temp2 = right
        right = xor(left, func_f(right, key))
        left = temp2
    return left, right


def encode(plain_text, r, current_key, ty):
    plain_text = change_hex_to_bin(plain_text)
    plain_text = translation(plain_text, ip)
    cipher_text = ''
    left = plain_text[:32]
    right = plain_text[32:]
    current_key_bin = bin(int(str(current_key), 16))[2:].rjust(64, '0')
    current_key_bin = translation(current_key_bin, pc1)
    key_left = current_key_bin[:28]
    key_right = current_key_bin[28:]
    left, right = wheel_structure(left, right, key_left, key_right, r, ty)
    cipher_text += right + left
    cipher_text = translation(cipher_text, ip_)
    cipher_text = hex(int(cipher_text, 2))[2:].upper().rjust(16, '0')
    return cipher_text


def main():
    a = input('请输入要加密的16个十六进制数字符串:')
    key = input('请输入加密密钥(16个十六进制数字符串:)')
    r = input('请输入加密轮数:')
    print('要加密的明文为：', a)
    a = encode(a, r, key, 1)
    print('密文：', a)
    a = encode(a, r, key, 0)
    print('解密后的明文：', a)


if __name__ == '__main__':
    main()

在table.py里存取几个需要用到的表

      60, 52, 44, 36, 28, 20, 12, 4,
      62, 54, 46, 38, 30, 22, 14, 6,
      64, 56, 48, 40, 32, 24, 16, 8,
      57, 49, 41, 33, 25, 17, 9, 1,
      59, 51, 43, 35, 27, 19, 11, 3,
      61, 53, 45, 37, 29, 21, 13, 5,
      63, 55, 47, 39, 31, 23, 15, 7]

ip_ = [40, 8, 48, 16, 56, 24, 64, 32,
       39, 7, 47, 15, 55, 23, 63, 31,
       38, 6, 46, 14, 54, 22, 62, 30,
       37, 5, 45, 13, 53, 21, 61, 29,
       36, 4, 44, 12, 52, 20, 60, 28,
       35, 3, 43, 11, 51, 19, 59, 27,
       34, 2, 42, 10, 50, 18, 58, 26,
       33, 1, 41, 9, 49, 17, 57, 25]

pc1 = [57, 49, 41, 33, 25, 17, 9,
       1, 58, 50, 42, 34, 26, 18,
       10, 2, 59, 51, 43, 35, 27,
       19, 11, 3, 60, 52, 44, 36,
       63, 55, 47, 39, 31, 23, 15,
       7, 62, 54, 46, 38, 30, 22,
       14, 6, 61, 53, 45, 37, 29,
       21, 13, 5, 28, 20, 12, 4]

pc2 = [14, 17, 11, 24, 1, 5,
       3, 28, 15, 6, 21, 10,
       23, 19, 12, 4, 26, 8,
       16, 7, 27, 20, 13, 2,
       41, 52, 31, 37, 47, 55,
       30, 40, 51, 45, 33, 48,
       44, 49, 39, 56, 34, 53,
       46, 42, 50, 36, 29, 32]

table_e = [32, 1, 2, 3, 4, 5,
           4, 5, 6, 7, 8, 9,
           8, 9, 10, 11, 12, 13,
           12, 13, 14, 15, 16, 17,
           16, 17, 18, 19, 20, 21,
           20, 21, 22, 23, 24, 25,
           24, 25, 26, 27, 28, 29,
           28, 29, 30, 31, 32, 1]

table_p = [16, 7, 20, 21,
           29, 12, 28, 17,
           1, 15, 23, 26,
           5, 18, 31, 10,
           2, 8, 24, 14,
           32, 27, 3, 9,
           19, 13, 30, 6,
           22, 11, 4, 25]


s_box = [
    # S1
    [14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
     0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
     4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
     15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13],

    # S2
    [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
     3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
     0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
     13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9],

    # S3
    [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
     13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
     13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
     1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12],

    # S4
    [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
     13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
     10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
     3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14],

    # S5
    [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
     14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
     4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
     11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3],

    # S6
    [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
     10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
     9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
     4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13],

    # S7
    [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
     13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
     1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
     6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12],

    # S8
    [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
     1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
     7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
     2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11],
]```