- Read a Base64 string from the console input. The string represents the IV bytes as a Base64 string. If the length of IV bytes is not expected, abort the program with a Python code
raise Exception('IV length mismatch') - Encrypt the padded plaintext bytes with the key and IV.
- Print the ciphertext bytes as a Base64 string.
- Decrypt the ciphertext bytes with the key and IV.
- Unpad the decrypted plaintext bytes with
pkcs7algorithm. - Print the unpadded bytes as a hex string.
- Decode the unpadded bytes with
utf-8encoding, and print the decoded text string.
Example Input & Output
Input:
I don't like deadbeef. 你呢？
1UO7ZnmwcT7KtScS2hAZV+aZ1Gk95HPK1EqcXT6rqoU=
6GXIzJ0GD/76WkTtgmaDYQ==
Output:
4920646f6e2774206c696b652064656164626565662e20e4bda0e591a2efbc9f10101010101010101010101010101010
c0LWy2BUg949eMO+G8NgxUzKVNNFys8EzavYFhP0Tc/mZM/UVVe4E3b34cEyu1Ze
not identical
4920646f6e2774206c696b652064656164626565662e20e4bda0e591a2efbc9f
I don't like deadbeef. 你呢？
Note: the first line of the example input is consisting of the following 26 characters:
| I | d | o | n | ’ | t | l | i | ||
|---|---|---|---|---|---|---|---|---|---|
| k | e | d | e | a | d | b | e | e | |
| f | . | 你 | 呢 | ？ |
solution code
from Crypto.Cipher import AES
import base64
class PrpCrypt(object):
def \_\_init\_\_(self, key, iv):
self.key = key
self.iv = iv
self.mode = AES.MODE_CBC
# pkcs7填充函数：
@staticmethod
def pkcs7\_padding(in_bytes: str):
pad_len: int = 16 - len(in_bytes) % 16
if pad_len == 0:
pad_len = 16
in_str: str = str(in_bytes) + str(hex(pad_len) \* pad_len).replace('0x', '')
return in_str
# pkcs7反填充函数：
@staticmethod
def pkcs7\_unpadding(in_hex_str: str) -> str:
end_str: str = in_hex_str[-2:]
if end_str == '01':
end_str: str = in_hex_str[0:-2]
else:
num: int = int(end_str[-2:], 16)
end_str: str = in_hex_str[0:-(2 \* num)]
return end_str
# AES加密函数：
def encrypt(self, text: bytes):
# Encrypt the padded plaintext bytes with the key and IV.
ciphertext = AES.new(self.key, self.mode, self.iv)
output_bytes: bytes = ciphertext.encrypt(bytes(text))
return output_bytes
# AES解密函数：
def decrypt(self, text: bytes):
plaintext = AES.new(self.key, self.mode, self.iv)
output_bytes = plaintext.decrypt(bytes(text))
return output_bytes
if __name__ == '\_\_main\_\_':
# Read a text string from the console input.
p_str: str = input('plaintext input:')
# Read a Base64 string from the console input.
key_b64: str = input('key input:')
key: bytes = base64.b64decode(key_b64)
IV_b64: str = input('IV input:')
IV: bytes = base64.b64decode(IV_b64)
# 异常处理函数：
def judge(bytes_1: bytes, bytes_2: bytes):
if len(bytes_1) % 24 != 0:
if len(bytes_1) % 16 != 0:
raise Exception('key length mismatch')
if len(bytes_2) % 16 != 0:
raise Exception('IV length mismatch ')
judge(key, IV)
pc = PrpCrypt(key, IV) # 初始化密钥
# Encode the text string with utf-8 encoding, as the plaintext bytes.
plaintext_str: str = p_str.encode('utf-8').hex()
# Print the padded bytes as a hex string.
print(pc.pkcs7_padding(plaintext_str))
padded_plaintext: bytes = bytes.fromhex(pc.pkcs7_padding(plaintext_str))
# Encrypt the padded plaintext bytes with the key and IV.
ciphertext: str = base64.b64encode(pc.encrypt(padded_plaintext)).decode('utf-8')
# Print the ciphertext bytes as a Base64 string.
print(ciphertext)
# Decrypt the ciphertext bytes with the key and IV.
ciphertext_bytes: bytes = bytes.fromhex(base64.b64decode(ciphertext).hex())
plaintext: str = base64.b64encode(pc.decrypt(ciphertext_bytes)).decode('utf-8')
if base64.b64decode(plaintext).hex() == ciphertext:
print('identical')
else:
print('not identical')
# Print the unpadded bytes as a hex string.
print(pc.pkcs7_unpadding(base64.b64decode(plaintext).hex()))
# Decode the unpadded bytes with utf-8 encoding, and print the decoded text string.
text_str: str = pc.pkcs7_unpadding(base64.b64decode(plaintext).hex())
text_string: str = bytes.fromhex(text_str).decode('utf-8')
print(text_string)
### 最后
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给大家准备的学习资料包括但不限于：
Python 环境、pycharm编辑器/永久激活/翻译插件
python 零基础视频教程
Python 界面开发实战教程
Python 爬虫实战教程
Python 数据分析实战教程
python 游戏开发实战教程
Python 电子书100本
Python 学习路线规划
**了解详情：https://docs.qq.com/doc/DSnl3ZGlhT1RDaVhV**
