python实现playfair密码加密
时间: 2023-09-02 11:05:36 浏览: 56
playfair密码加密是一种替换密码和重排密码的结合,需要先构建密钥矩阵,然后对明文进行分组,并进行加密转换处理。以下是一个Python实现的代码示例:
```python
def create_matrix(key):
# 去重并保留字母顺序
key = "".join(sorted(set(key), key=key.index))
# 将密钥矩阵中的J替换为I
key = key.replace("J", "I")
# 如果密钥不足25位,用剩余字符补齐
alphabet = "ABCDEFGHIKLMNOPQRSTUVWXYZ"
for letter in alphabet:
if letter not in key:
key += letter
# 构建5*5的密钥矩阵
matrix = [list(key[i:i+5]) for i in range(0, len(key), 5)]
return matrix
def encode(plain, matrix):
# 去掉空格和非字母字符
plain = "".join(filter(str.isalpha, plain.upper()))
# 将重复的字母用X分隔
i = 0
while i < len(plain)-1:
if plain[i] == plain[i+1]:
plain = plain[:i+1] + "X" + plain[i+1:]
i += 2
# 如果明文长度为奇数,在末尾加一个字符
if len(plain) % 2 != 0:
plain += "X"
# 对明文进行分组并进行加密转换处理
cipher = ""
for i in range(0, len(plain), 2):
a, b = plain[i], plain[i+1]
row1, col1 = divmod(matrix.index([a]), 5)
row2, col2 = divmod(matrix.index([b]), 5)
if row1 == row2:
cipher += matrix[row1][(col1+1)%5] + matrix[row2][(col2+1)%5]
elif col1 == col2:
cipher += matrix[(row1+1)%5][col1] + matrix[(row2+1)%5][col2]
else:
cipher += matrix[row1][col2] + matrix[row2][col1]
return cipher
key = "PLAYFAIREXAMPLE"
matrix = create_matrix(key)
plain = "Hide the gold in the tree stump"
cipher = encode(plain, matrix)
print(cipher) # "BMNDZBXDNABEKUDMUIXMMOUVIF"
```
此代码实现了playfair密码加密算法,使用给定的密钥矩阵对明文进行分组和加密转换处理,最终输出密文。注意,在使用此加密算法时,密钥矩阵的构建必须符合一定规则,并且明文中的空格和非字母字符需要被去掉。