affine_cipher 仿射加密法

affine_cipher 仿射加密法

概念

仿射加密法与单码加密法没什么不同，因为明文的每个字母分别只映射到一个密文字母。仿射密码的加密算法就是一个线性变换，即对任意的明文字符x，对应的密文字符为$y\equiv ax+ b (mod(26)) $ ，其中，\(a,b∈Z26\)，且要求\(gcd(a,26)\)=1,函数e(x)称为仿射加密函数。

算法

• SYMBOLS :符号表

SYMBOLS = (
    r""" !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`"""
    r"""abcdefghijklmnopqrstuvwxyz{|}~"""
)

• encrypt_message(key: int, message: str) -> str
  根据key 值，加密
• decrypt_message(key: int, message: str) -> str
  根据key 值，解密

代码

[affine_cipher.py]{..\src\ciphers\affine_cipher.py}

"""
Prepare
   1. sys.path 中增加 TheAlgorithms\src 子模块

"""
import sys
sys.path.append('E:\dev\AI\TheAlgorithms\src')

案例一：

对明文进行加密
对密文进行解密

from ciphers.affine_cipher import encrypt_message,decrypt_message
"""
>>> encrypt_message(4545, 'The affine cipher is a type of monoalphabetic '
                        'substitution cipher.')
    'VL}p MM{I}p~{HL}Gp{vp pFsH}pxMpyxIx JHL O}F{~pvuOvF{FuF{xIp~{HL}Gi'
>>> decrypt_message(4545, 'VL}p MM{I}p~{HL}Gp{vp pFsH}pxMpyxIx JHL O}F{~pvuOvF{FuF'
                      '{xIp~{HL}Gi')
  'The affine cipher is a type of monoalphabetic substitution cipher.'
"""
sPlain_msg='''The affine cipher is a type of monoalphabetic \\                            substitution cipher.'''

sCipher_msg = ''
key = 4545
sCipher_msg = encrypt_message(key,sPlain_msg)
print("密文:"+sCipher_msg)
print("明文:"+decrypt_message(key,sCipher_msg))

密文:VL}p MM{I}p~{HL}Gp{vp pFsH}pxMpyxIx JHL O}F{~pRppppppppppppppppppppppppppppvuOvF{FuF{xIp~{HL}Gi
明文:The affine cipher is a type of monoalphabetic \                            substitution cipher.