我使用Pycrypto加密器和解密器与AES 256对称密钥算法。与解密时间相比，我的加密部分花费了更多的时间。这有什么好理由吗？
我尝试了16 MB文件：
加密时间= 3.31秒 解密时间= 0.18秒
有人可以帮我说明这可能是什么原因吗？
加密逻辑如下所示：
def encrypt_file(key, infile, chunksize=64 * 1024):
""" Encrypts a file using AES (CBC mode) with the
given key.
key:
The encryption key - a string that must be
either 16, 24 or 32 bytes long. Longer keys
are more secure.
infile:
input file
chunksize:
Sets the size of the chunk which the function
uses to read and encrypt the file. Larger chunk
sizes can be faster for some files and machines.
chunksize must be divisible by 16.
"""
iv = os.urandom(16)
encryptor = AES.new(key, AES.MODE_CBC, iv)
infile.seek(0, os.SEEK_END)
filesize = infile.tell()
infile.seek(0, os.SEEK_SET)
encrypted = b'';
encrypted += struct.pack('<Q', filesize)
encrypted += iv
while True:
chunk = infile.read(chunksize)
if len(chunk) == 0:
break
elif len(chunk) % 16 != 0:
chunk += b' ' * (16 - len(chunk) % 16)
encrypted += encryptor.encrypt(chunk)
return encrypted
解密逻辑如下所示：
def decrypt_file(key, infile, out_filename, chunksize=24*1024):
""" Decrypts a file using AES (CBC mode) with the
given key.
"""
if key == '':
with open(out_filename, 'wb') as outfile:
for line in infile:
outfile.write(line)
return outfile.name
origsize = struct.unpack('<Q', infile.read(struct.calcsize('Q')))[0]
iv = infile.read(16)
decryptor = AES.new(key, AES.MODE_CBC, iv)
# for line in infile:
# print(line)
with open(out_filename, 'wb+') as outfile:
while True:
chunk = infile.read(chunksize)
if len(chunk) == 0:
break
outfile.write(decryptor.decrypt(chunk))
outfile.truncate(origsize)
return outfile.name