DES アルゴリズム Python 実装ソース コード

DES の概要

DES は、1970 年代に IBM によって元々開発された対称キー暗号化アルゴリズムです。DES は、56 ビット キーと一連の置換、置換、および XOR 操作を使用して、データの暗号化と復号化を行います。DES は強力な暗号化アルゴリズムであると考えられていますが、現在では鍵の長さが短いため安全ではないと考えられており、AES などのより強力なアルゴリズムに置き換えられています。

アルゴリズム実装フローチャート

暗号化アルゴリズム

鍵拡張アルゴリズム

64 ビット サブキーは、順列選択 1、循環左シフト、および順列選択 2を通じて16 個の48 ビット サブキーを生成します。循環左シフト 1 ビット

、

ソースコード

暗号化アルゴリズム

IP_table = [58, 50, 42, 34, 26, 18, 10, 2,
            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_table_reverse = [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]
E_table = [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
           ]
S_boxs = [
# 定义8个S盒
    # S1盒
    [
        [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盒
    [
        [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盒
    [
        [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盒
[
    [ 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盒
[
    [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盒
[
    [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盒
[
    [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]
]


]
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
]
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]


def input_binary(ls, str, length):
    while True:  # input key
        s = input("please input {}(length is {} bit):".format(str, length))
        if len(s) != length:
            print("the length of {} should be {},please input again:".format(str, length))
        else:
            break;
    for c in s:
        ls.append(int(c))


def output_ls(ls, s):
    print(s+":")
    space = 0
    for i in ls:
        print(i, end="")
        space += 1
        if space == 8:
            space = 0
            print(" ", end="")
    print("\n")




def product_transformation(ls, k, od):
    """

    :param ls: 乘积变换输入
    :param k: 每一轮的轮密钥
    :param od: 判断是不是第16轮
    :return:
    """
    l = ls[0:32]
    r = ls[32:64]
    s = []
    s2 = [0]*32
    temp = []
    for i in range(0,48):                # 选择运算扩展位数
        temp.append(r[E_table[i]-1])
    temp = [a^b for a,b in zip(temp,k)]  # 结果与轮密钥k异或
    for i in range(0,8):                 # 查S盒
        index = i*6
        row =2*temp[index]+temp[index+5]
        col = 8*temp[index+1]+4*temp[index+2]+2*temp[index+3]+temp[index+4]
        s_box = S_boxs[i]
        a = s_box[row][col]
        st = bin(a)[2:]
        binary_list = [int(bit) for bit in st]
        s1=[0]*(4-len(binary_list))+binary_list
        s.extend(s1)
        # 置换运算P
    for i in range(0,32):
        s2[i] = s[P[i]-1]
        # 异或运算
    xor_list = [a ^ b for a, b in zip(l, s2)]    # 结果与Li异或
    lis = [0]*32
    for i in range(0, 32):
        lis[i] = ls[i+32]
    ls = ls[32:]+xor_list
    return ls


def generate_round_key(ls, round_key):
    bit_num = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
    ls1 = [0]*56
    k = [0]*48
    for i in range(0, 56):
       ls1[i] = ls[PC1[i]-1]      # PC1置换
    for i in range(0, 16):
        ls1 = ls1[bit_num[i]:28]+ls1[0:bit_num[i]]+ls1[28+bit_num[i]:]+ls1[28:28+bit_num[i]]  # 循环左移
        for j in range(0, 48):
            k[j] = ls1[PC2[j]-1] # PC2置换
        round_key.append(k.copy())


def des_encode():
    key = [] # 0011000100110010001100110011010000110101001101100011011100111000
    M = []  #  0011000000110001001100100011001100110100001101010011011000110111
    round_key = []
    temp_list = [0]*64
    ciphertext = [0]*64
    input_binary(M, "plaintext", 64)  # 输入明文
    input_binary(key, "key", 64)        # input 密钥

    # sk = "0011000100110010001100110011010000110101001101100011011100111000"  # private key
    # sm = "0011000000110001001100100011001100110100001101010011011000110111"   # plaintext
    # for c in sk:
    #     key.append(int(c))
    # for c in sm:
    #         M.append(int(c))

    generate_round_key(key, round_key)
    for i in range(0, 64):                   # IP 置换
        temp_list[i] = M[IP_table[i]-1]
    for i in range(0, 16):
        if i != 15:
            od = 0
        else:od = 1
        temp_list=product_transformation(temp_list,round_key[i],od)   # od=1 第16轮特殊处理
    temp_list=temp_list[32:]+temp_list[0:32]
    for i in range(0, 64):
        ciphertext[i] = temp_list[IP_table_reverse[i]-1]
    output_ls(ciphertext,"ciphertext:")


des_encode()

復号化アルゴリズム

        if i != 15:
            od = 0
        else: od = 1
        temp_list = product_transformation(temp_list, round_key[15-i], od)

対応する位置を置き換えるだけです。DES
の演算はインボリューション演算であるため、ラウンド キーの使用順序が逆になることを除いて、暗号化アルゴリズムと復号化アルゴリズムは同じです。つまり、round_key16 が最初の反復で使用されます...round_key1 16 回目の反復で使用されます。

演算結果

please input plaintext(length is 64 bit):0011000000110001001100100011001100110100001101010011011000110111
please input key(length is 64 bit):0011000100110010001100110011010000110101001101100011011100111000
ciphertext::
10001011 10110100 01111010 00001100 11110000 10101001 01100010 01101101