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Data Encryption Standard (DES)

最流行的对称密钥算法是数据加密标准 (DES),且 Python 包含一个软件包,该软件包包括 DES 算法背后的逻辑。

Installation

Python 中安装 DES 包 pyDES 的命令为:

pip install pyDES
data = "DES Algorithm Implementation" k = pyDes.des("DESCRYPT", pyDes.CBC, "\0\0\0\0\0\0\0\0", pad=None, padmode=pyDes.PAD_PKCS5) d = k.encrypt(data) print "Encrypted: %r" % d print "Decrypted: %r" % k.decrypt(d) assert k.decrypt(d) == data

它调用变量 padmode ,它获取所有 DES 算法实现所需的包,并以特定方式执行加密和解密。

Output

以下为上述代码运行后的输出:

Asymmetric Cryptography

它也被称为 public key cryptography. 。它的工作方式与对称加密相反。这意味着它需要两个密钥:一个用于加密,另一个用于解密。公钥用于加密,而私钥用于解密。

Drawback

由于密钥的长度,它导致加密速度较低。

Key management is crucial.

def generate_keys(): # key length must be a multiple of 256 and >= 1024 modulus_length = 256*4 privatekey = RSA.generate(modulus_length, Random.new().read) publickey = privatekey.publickey() return privatekey, publickey def encrypt_message(a_message , publickey): encrypted_msg = publickey.encrypt(a_message, 32)[0] encoded_encrypted_msg = base64.b64encode(encrypted_msg) return encoded_encrypted_msg def decrypt_message(encoded_encrypted_msg, privatekey): decoded_encrypted_msg = base64.b64decode(encoded_encrypted_msg) decoded_decrypted_msg = privatekey.decrypt(decoded_encrypted_msg) return decoded_decrypted_msg a_message = "This is the illustration of RSA algorithm of asymmetric cryptography" privatekey , publickey = generate_keys() encrypted_msg = encrypt_message(a_message , publickey) decrypted_msg = decrypt_message(encrypted_msg, privatekey) print "%s - (%d)" % (privatekey.exportKey() , len(privatekey.exportKey())) print "%s - (%d)" % (publickey.exportKey() , len(publickey.exportKey())) print " Original content: %s - (%d)" % (a_message, len(a_message)) print "Encrypted message: %s - (%d)" % (encrypted_msg, len(encrypted_msg)) print "Decrypted message: %s - (%d)" % (decrypted_msg, len(decrypted_msg))