如何在不再次生成密钥对的情况下进行加密/解密?

Question

我一直在自己做一个项目，并使用此网站的代码作为指导。有什么办法，我可以将密钥的生成放入一个文件中，并将加密/解密放入另一个文件中。如何在不生成另一对密钥的情况下定义bob_box？

根。.PY：

import libnacl.public
def genkeys():
bob = libnacl.public.SecretKey()
alice = libnacl.public.SecretKey()
bob_box = libnacl.public.Box(bob.sk, alice.pk)
alice_box = libnacl.public.Box(alice.sk, bob.pk)
genkeys()

ENDEcrypt：

import libnacl.public
from GEN import genkeys
msg = '1234'
# Bob's box encrypts messages for Alice
bob_ctxt = bob_box.encrypt(msg)
# Alice's box decrypts messages from Bob
bclear = alice_box.decrypt(bob_ctxt)
# Alice can send encrypted messages which only Bob can decrypt
alice_ctxt = alice_box.encrypt(msg)
aclear = bob_box.decrypt(alice_ctxt)

运行 ENDEcrypt 时的输出：

Traceback (most recent call last):
File "/home/pi/Desktop/BOBALICE/endecrypt.py", line 7, in <module>
bob_ctxt = bob_box.encrypt(msg)
NameError: name 'bob_box' is not defined

Answer 1

libnacl 的 API 的设计方式是，想要安全通信的双方必须以某种方式交换他们的公钥。假设爱丽丝想向鲍勃发送一条消息。

# Alice's computer:                             Bob's computer:
alice_sign = libnacl.public.SecretKey()         bob_enc = libnacl.public.SecretKey()
alice_spk_h = alice_sign.hex_pk()               bob_epk_h = bob_enc.hex_pk()
# magic happens where alice_spk_h goes to Bob and bob_epk_h goes to alice (i.e. by phone)
bob_epk = libnacl.public.PublicKey(bob_epk_h)   alice_spk = libnacl.public.PublicKey(
alice_spk_h)
alice_box = libnacl.public.Box(                 bob_box = libnacl.public.Box(
alice_sign.sk, bob_epk)                         bob_enc.sk, alice_spk)
# preparation is done, let's start encrypting...
ct = alice_box.encrypt(msg)
# send ct to Bob (the message is protected)
msg = bob_box.decrypt(ct)

如您所见，您需要分别处理公钥和密钥，以便在通信方的计算机之间发送它们。您不能将它们组合成一种方法，因为这将与 libnacl 公钥加密的使用场景相矛盾。

请记住，对于每方一个密钥对，只允许向一个方向发送加密消息。如果您需要发回消息，那么每一方都需要有两个密钥(一个用于签名，一个用于加密;请注意，我以某种方式命名了 Alice 和 Bob 的密钥以明确这一点(。

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有没有办法在一个文件中生成密钥并将密钥存储到一个盒子中+加密/解密到另一个文件中？

是的，但是在这里您必须考虑这些文件在做什么。Python 文件是代码。如果从命令行运行生成 SecretKey 的代码，则需要以某种方式存储它，因为再次运行代码会更改密钥。

gen.py

import libnacl.public
def genkey():
return libnacl.public.SecretKey()
def gen_keys_and_save():
# Generate two key pairs and store them for later use
enc = genkey()
enc.save('myencsecret.key')
with open('myencpublic.key', 'w') as pkf:
pkf.write(enc.hex_pk())
sign = genkey()
sign.save('mysignsecret.key')
with open('mysignpublic.key', 'w') as pkf:
pkf.write(sign.hex_pk())
if __name__ == "__main__":
# this code only runs when executed directly (i.e. from command line)
gen_keys_and_save()

enc.py

import libnacl.public
import libnacl.utils
def encrypt(mysignsecret, theirencpublic, data):
box = libnacl.public.Box(mysignsecret, theirencpublic)
return box.encrypt(data)
def parse_and_encrypt(mysignsecretfile, theirencpublicfile, data):
sk = libnacl.utils.load_key(mysignsecretfile)
with open(theirencpublicfile, 'r') as pkf:
pk = libnacl.public.PublicKey(pkf.read())
return encrypt(sk, pk, data)
if __name__ == "__main__":
parse_and_encrypt('mysignsecret.key', 'theirencpublic.key', 'some kind of msg')

dec.py

import libnacl.public
def decrypt(myencsecret, theirsignpublic, ciphertext):
box = libnacl.public.Box(myencsecret, theirsignpublic)
return box.decrypt(ciphertext)
# similar to enc.py ...

现在你可以像这样运行它：

$ python gen.py

现在你需要接收theirencpublic.key并发送mysignpublic.key。完成此操作后，您可以执行此操作：

$ python enc.py