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import sys
# =============================================================================
# DES 算法常量定义 (标准表)
# =============================================================================
# 初始置换表 (IP)
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
]
# 逆初始置换表 (IP^-1)
IP_INV_TABLE = [
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
]
# 扩展置换表 (E-Box): 32位 -> 48位
E_BOX_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
]
# P盒置换表 (P-Box): 32位 -> 32位
P_BOX_TABLE = [
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
]
# 密钥置换表 1 (PC-1): 64位 -> 56位 (去掉了校验位)
PC1_TABLE = [
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
]
# 密钥置换表 2 (PC-2): 56位 -> 48位
PC2_TABLE = [
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
]
# 密钥左移位数表 (每轮左移的位数)
SHIFT_SCHEDULE = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
# S盒 (S-Boxes): 8个 S盒，每个将 6位 映射为 4位
S_BOXES = [
# 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]
]
]
# =============================================================================
# 辅助工具函数
# =============================================================================
def str_to_bin(text):
"""将字符串转换为二进制字符串 (每个字符8位)"""
return ''.join(format(ord(c), '08b') for c in text)
def bin_to_str(binary):
"""将二进制字符串转换为 ASCII 字符串"""
# 每8位一组
chars = [binary[i:i+8] for i in range(0, len(binary), 8)]
return ''.join(chr(int(c, 2)) for c in chars)
def hex_to_bin(hex_str):
"""将十六进制字符串转换为二进制字符串"""
# 每个hex字符对应4位bin
return ''.join(format(int(c, 16), '04b') for c in hex_str)
def bin_to_hex(binary):
"""将二进制字符串转换为十六进制字符串"""
# 每4位一组
hex_str = ""
for i in range(0, len(binary), 4):
chunk = binary[i:i+4]
hex_str += format(int(chunk, 2), 'x').upper()
return hex_str
def permute(data, table):
"""
通用置换函数
data: 输入的二进制字符串
table: 置换表 (1-based index)
"""
return ''.join(data[i - 1] for i in table)
def xor(a, b):
"""对两个等长的二进制字符串进行异或运算"""
return ''.join('1' if x != y else '0' for x, y in zip(a, b))
def left_shift(data, n):
"""循环左移 n 位"""
return data[n:] + data[:n]
# =============================================================================
# 填充与密钥处理 (新增)
# =============================================================================
def pkcs7_pad(text):
"""PKCS#7 填充: 将文本填充为 8 的倍数"""
pad_len = 8 - (len(text) % 8)
padding = chr(pad_len) * pad_len
return text + padding
def pkcs7_unpad(text):
"""PKCS#7 去填充"""
pad_len = ord(text[-1])
return text[:-pad_len]
def process_key(key_str):
"""处理密钥: 确保是 8 字节"""
# 如果太短，补 \0
if len(key_str) < 8:
return key_str.ljust(8, '\0')
# 如果太长，截断 (实际应用中通常做 Hash)
elif len(key_str) > 8:
return key_str[:8]
return key_str
# =============================================================================
# 核心逻辑函数
# =============================================================================
def generate_subkeys(key_bin, verbose=False):
"""
生成 16 个 48 位的子密钥
key_bin: 64位二进制密钥
"""
if verbose:
print(f"\n[密钥生成] 原始密钥 (64位): {key_bin}")
# 1. PC-1 置换 (64位 -> 56位)
key_56 = permute(key_bin, PC1_TABLE)
if verbose:
print(f"[密钥生成] PC-1置换后 (56位): {key_56}")
# 分为左右两部分 C0, D0
c = key_56[:28]
d = key_56[28:]
subkeys = []
for i in range(16):
# 2. 循环左移
shift = SHIFT_SCHEDULE[i]
c = left_shift(c, shift)
d = left_shift(d, shift)
# 合并
cd = c + d
# 3. PC-2 置换 (56位 -> 48位)
k = permute(cd, PC2_TABLE)
subkeys.append(k)
if verbose:
print(f" Round {i+1:2d}: 左移 {shift} 位 -> 子密钥: {bin_to_hex(k)}")
return subkeys
def f_function(right_data, subkey, verbose=False):
"""
Feistel 轮函数 f(R, K)
right_data: 32位
subkey: 48位
"""
# 1. 扩展置换 E (32 -> 48)
expanded_r = permute(right_data, E_BOX_TABLE)
# 2. 与子密钥异或
xored = xor(expanded_r, subkey)
# 3. S盒代换 (48 -> 32)
# 将48位分为8组，每组6位
s_box_output = ""
for i in range(8):
chunk = xored[i*6 : (i+1)*6]
# 行号：第1位和第6位
row = int(chunk[0] + chunk[5], 2)
# 列号：第2,3,4,5位
col = int(chunk[1:5], 2)
# 查表
val = S_BOXES[i][row][col]
# 转为4位二进制
s_box_output += format(val, '04b')
# 4. P盒置换 (32 -> 32)
p_box_output = permute(s_box_output, P_BOX_TABLE)
return p_box_output
def des_process(data_bin, key_bin, mode='encrypt', verbose=True):
"""
DES 核心处理流程 (加密/解密共用)
data_bin: 64位数据
key_bin: 64位密钥
mode: 'encrypt' 或 'decrypt'
"""
action_name = "加密" if mode == 'encrypt' else "解密"
if verbose:
print(f"\n{'='*20} 开始 DES {action_name} (单块) {'='*20}")
print(f"输入数据 (Hex): {bin_to_hex(data_bin)}")
print(f"密钥 (Hex): {bin_to_hex(key_bin)}")
# 1. 生成子密钥
subkeys = generate_subkeys(key_bin, verbose=verbose)
# 如果是解密，子密钥顺序反转
if mode == 'decrypt':
subkeys = subkeys[::-1]
if verbose:
print(f"\n[注意] 解密模式：子密钥顺序已反转")
# 2. 初始置换 IP
ip_data = permute(data_bin, IP_TABLE)
if verbose:
print(f"\n[初始置换 IP] 结果: {bin_to_hex(ip_data)}")
# 将数据分为左右两部分 L0, R0
l = ip_data[:32]
r = ip_data[32:]
if verbose:
print(f"初始 L0: {bin_to_hex(l)}")
print(f"初始 R0: {bin_to_hex(r)}")
print("-" * 60)
# 3. 16轮迭代
for i in range(16):
prev_l = l
prev_r = r
# L(i) = R(i-1)
l = prev_r
# R(i) = L(i-1) XOR f(R(i-1), K(i))
f_res = f_function(prev_r, subkeys[i], verbose)
r = xor(prev_l, f_res)
if verbose:
print(f"Round {i+1:2d}:")
print(f" K{i+1 if mode=='encrypt' else 16-i}: {bin_to_hex(subkeys[i])}")
print(f" L{i+1}: {bin_to_hex(l)} (from old R)")
print(f" f(R,K): {bin_to_hex(f_res)}")
print(f" R{i+1}: {bin_to_hex(r)} (L XOR f)")
# 4. 32位互换
final_rl = r + l
if verbose:
print("-" * 60)
print(f"[32位互换] 结果 (R16 L16): {bin_to_hex(final_rl)}")
# 5. 逆初始置换 IP^-1
cipher_bin = permute(final_rl, IP_INV_TABLE)
if verbose:
print(f"\n[{action_name}结果] (Hex): {bin_to_hex(cipher_bin)}")
print(f"{'='*20} 结束 DES {action_name} {'='*20}\n")
return cipher_bin
# =============================================================================
# 高级接口 (支持不定长数据)
# =============================================================================
def des_encrypt_ecb(text, key, verbose=False):
"""ECB 模式加密"""
key = process_key(key)
key_bin = str_to_bin(key)
# 1. 填充
text_padded = pkcs7_pad(text)
print(f"原始长度: {len(text)}, 填充后长度: {len(text_padded)}")
ciphertext_hex = ""
# 2. 分组处理
for i in range(0, len(text_padded), 8):
block = text_padded[i:i+8]
print(f"\n>>> 处理第 {i//8 + 1} 块: {block}")
block_bin = str_to_bin(block)
cipher_bin = des_process(block_bin, key_bin, mode='encrypt', verbose=verbose)
ciphertext_hex += bin_to_hex(cipher_bin)
return ciphertext_hex
def des_decrypt_ecb(hex_str, key, verbose=False):
"""ECB 模式解密"""
key = process_key(key)
key_bin = str_to_bin(key)
plaintext = ""
# 1. 分组处理
for i in range(0, len(hex_str), 16):
block_hex = hex_str[i:i+16]
print(f"\n>>> 处理第 {i//16 + 1} 块 (Hex): {block_hex}")
block_bin = hex_to_bin(block_hex)
plain_bin = des_process(block_bin, key_bin, mode='decrypt', verbose=verbose)
plaintext += bin_to_str(plain_bin)
# 2. 去填充
return pkcs7_unpad(plaintext)
# =============================================================================
# 用户接口
# =============================================================================
def main():
# 示例：不定长数据和短密钥
raw_key = "secret" # 6字节 (不足8字节)
raw_text = "hello fanshanng" # 15字节
print(f"原始明文: {raw_text}")
print(f"原始密钥: {raw_key}")
# 1. 加密
print("\n开始加密...")
# verbose=False 避免打印太多细节，只看分组流程
cipher_hex = des_encrypt_ecb(raw_text, raw_key, verbose=False)
print(f"\n最终密文 (Hex): {cipher_hex}")
# 2. 解密
print("\n开始解密...")
decrypted_text = des_decrypt_ecb(cipher_hex, raw_key, verbose=False)
print(f"\n最终验证:")
print(f" 原始明文: {raw_text}")
print(f" 解密明文: {decrypted_text}")
print(f" 匹配成功: {raw_text == decrypted_text}")
if __name__ == "__main__":
main()
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