Question

本章是前一章的延续，我们使用RSA算法逐步实现加密，并详细讨论它。

用于解密密文的函数如下 -

def decrypt(ciphertext, priv_key):
   cipher = PKCS1_OAEP.new(priv_key)
   return cipher.decrypt(ciphertext)

对于公钥加密或非对称密钥加密，重要的是保持两个重要的功能，即Authentication和Authorization 。

授权 (Authorization)

授权是确认发件人是唯一传送邮件的人的过程。 以下代码解释了这一点 -

def sign(message, priv_key, hashAlg="SHA-256"):
   global hash
   hash = hashAlg
   signer = PKCS1_v1_5.new(priv_key)
   if (hash == "SHA-512"):
      digest = SHA512.new()
   elif (hash == "SHA-384"):
      digest = SHA384.new()
   elif (hash == "SHA-256"):
      digest = SHA256.new()
   elif (hash == "SHA-1"):
      digest = SHA.new()
   else:
      digest = MD5.new()
   digest.update(message)
   return signer.sign(digest)

身份验证 (Authentication)

验证方法可以通过验证方法进行验证，如下所述 -

def verify(message, signature, pub_key):
   signer = PKCS1_v1_5.new(pub_key)
   if (hash == "SHA-512"):
      digest = SHA512.new()
   elif (hash == "SHA-384"):
      digest = SHA384.new()
   elif (hash == "SHA-256"):
      digest = SHA256.new()
   elif (hash == "SHA-1"):
      digest = SHA.new()
   else:
      digest = MD5.new()
   digest.update(message)
   return signer.verify(digest, signature)

验证数字签名以及发件人和收件人的详细信息。 为安全起见，这增加了更多的重量年龄。

RSA密码解密

您可以使用以下代码进行RSA密码解密 -

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA512, SHA384, SHA256, SHA, MD5
from Crypto import Random
from base64 import b64encode, b64decode
hash = "SHA-256"
def newkeys(keysize):
   random_generator = Random.new().read
   key = RSA.generate(keysize, random_generator)
   private, public = key, key.publickey()
   return public, private
def importKey(externKey):
   return RSA.importKey(externKey)
def getpublickey(priv_key):
   return priv_key.publickey()
def encrypt(message, pub_key):
   cipher = PKCS1_OAEP.new(pub_key)
   return cipher.encrypt(message)
def decrypt(ciphertext, priv_key):
   cipher = PKCS1_OAEP.new(priv_key)
   return cipher.decrypt(ciphertext)
def sign(message, priv_key, hashAlg = "SHA-256"):
   global hash
   hash = hashAlg
   signer = PKCS1_v1_5.new(priv_key)
   if (hash == "SHA-512"):
      digest = SHA512.new()
   elif (hash == "SHA-384"):
      digest = SHA384.new()
   elif (hash == "SHA-256"):
      digest = SHA256.new()
   elif (hash == "SHA-1"):
      digest = SHA.new()
   else:
      digest = MD5.new()
   digest.update(message)
   return signer.sign(digest)
def verify(message, signature, pub_key):
   signer = PKCS1_v1_5.new(pub_key)
   if (hash == "SHA-512"):
      digest = SHA512.new()
   elif (hash == "SHA-384"):
      digest = SHA384.new()
   elif (hash == "SHA-256"):
      digest = SHA256.new()
   elif (hash == "SHA-1"):
      digest = SHA.new()
   else:
      digest = MD5.new()
   digest.update(message)
   return signer.verify(digest, signature)