普莱菲尔密码矩阵生成算法

python提供了普莱菲尔密码的加解密包：pycipher

下载地址：https://pypi.python.org/pypi/pycipher

安装：python setup.py install

基本使用：

from pycipher import Playfair

print Playfair('CULTREABDFGHIKMNOPQSVWXYZ').encipher('THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG')
print Playfair('CULTREABDFGHIKMNOPQSVWXYZ').decipher('UKDNLHTGFLWUSEPWHLISNPCGCRGAUBVZAQIV')

输出：

UKDNLHTGFLWUSEPWHLISNPCGCRGAUBVZAQIV
THEQUICKBROWNFOXIUMPSOVERTHELAZYDOGX

# *-* coding=utf-8*-*
import string

def key_deal(key):
    strs = ''
    key = string.lower(key)
    for i in key:
        if i in strs:
            pass
        else:
            strs = strs + i
    return strs

def get_matrix(key):
    matrix = [([''] * 5) for i in range(5)]
    temp = key_deal(key)
    # print temp
    charset = string.lowercase
    dic = {chr(i+96): i for i in range(1, 27)}
    a = -1
    b = -1
    k = 0
    m = 0
    for j in range(5):  # 列
        for i in range(5):  # 行
            if k < len(temp):
                if dic.get(temp[k]) == 9 or dic.get(temp[k]) == 10:
                    a = i
                    b = j
                    matrix[i][j] = temp[k]
                    # print i, j, a, b, k, temp[k], matrix[i][j]
                    k += 1
                    continue
                else:
                    matrix[i][j] = temp[k]
                    # print i, j, a, b, k, temp[k], matrix[i][j]
                    k += 1
                    continue
            else:
                while m < len(dic):
                    if dic.get(charset[m]) == 9 or dic.get(charset[m]) == 10:
                        if a != -1 or b != -1:
                            matrix[a][b] = matrix[a][b] + charset[m]
                            m += 1   # matrix[i][j]还没定，需要继续
                        else:
                            matrix[i][j] = charset[m]
                            a = i
                            b = j
                            # print i, j, a, b, m, charset[m], matrix[i][j]
                            m += 1
                            break
                    else:
                        if charset[m] in temp:
                            m += 1
                        else:
                            matrix[i][j] = charset[m]
                            # print i, j, a, b, m, charset[m], matrix[i][j]
                            m += 1
                            break
    # for i in range(5):
    #     for j in range(5):
    #         print i, j, matrix[i][j]
    # return matrix

if __name__ == '__main__':
    key = 'CULTURE'
    matrix = get_matrix(key)
    plaintext = 'THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG'
    strs = string.lower(''.join(plaintext.split(' ')))
    if len(strs) % 2 != 0:
        strs += 'x'
    print strs