如何读取 PEM + PKCS#1 格式的 RSA 公钥

2022-01-10 00:00:00 python cryptography x509 pycrypto key-management

问题描述

我有一个 PEM 格式的 RSA 公钥 + PKCS#1(我猜):

I have a RSA public key in PEM format + PKCS#1(I guess):

-----BEGIN RSA PUBLIC KEY-----
MIGJAoGBAJNrHWRFgWLqgzSmLBq2G89exgi/Jk1NWhbFB9gHc9MLORmP3BOCJS9k
onzT/+Dk1hdZf00JGgZeuJGoXK9PX3CIKQKRQRHpi5e1vmOCrmHN5VMOxGO4d+zn
JDEbNHODZR4HzsSdpQ9SGMSx7raJJedEIbr0IP6DgnWgiA7R1mUdAgMBAAE=
-----END RSA PUBLIC KEY-----

我想在 Python 中获取其 ASN1 编码版本的 SHA1 摘要.第一步应该是读取这个密钥，但是我在 PyCrypto 中没有这样做:

I want to get the SHA1 digest of its ASN1 encoded version in Python. The first step should be to read this key, but I failed to do it in PyCrypto:

>> from Crypto.PublicKey import RSA
>> RSA.importKey(my_key)
ValueError: RSA key format is not supported

PyCrypto 文档说 PEM + PKCS#支持1，所以我很困惑.我也试过 M2Crypto，但事实证明 M2Crypto 不支持 PKCS#1，只支持 X.509.

The documentation of PyCrypto says PEM + PKCS#1 is supported, so I'm confused. I've also tried M2Crypto, but it turns out that M2Crypto does not support PKCS#1 but only X.509.

解决方案

PyCrypto 支持 PKCS#1，因为它可以读取 X.509 SubjectPublicKeyInfo 对象包含一个以 PKCS#1 编码的 RSA 公钥.

PyCrypto supports PKCS#1 in the sense that it can read in X.509 SubjectPublicKeyInfo objects that contain an RSA public key encoded in PKCS#1.

相反，在您的密钥中编码的数据是一个纯 RSAPublicKey 对象(即具有两个整数、模数和公共指数的 ASN.1 SEQUENCE).

Instead, the data encoded in your key is a pure RSAPublicKey object (that is, an ASN.1 SEQUENCE with two INTEGERs, modulus and public exponent).

您仍然可以阅读它.尝试类似:

You can still read it in though. Try something like:

from Crypto.PublicKey import RSA
from Crypto.Util import asn1
from base64 import b64decode

key64 = 'MIGJAoGBAJNrHWRFgWLqgzSmLBq2G89exgi/Jk1NWhbFB9gHc9MLORmP3BOCJS9k
onzT/+Dk1hdZf00JGgZeuJGoXK9PX3CIKQKRQRHpi5e1vmOCrmHN5VMOxGO4d+znJDEbNHOD
ZR4HzsSdpQ9SGMSx7raJJedEIbr0IP6DgnWgiA7R1mUdAgMBAAE='

keyDER = b64decode(key64)
seq = asn1.DerSequence()
seq.decode(keyDER)
keyPub = RSA.construct( (seq[0], seq[1]) )

<小时>

从 2.6 版开始，PyCrypto 还可以导入 RsaPublicKey ASN.1 对象.代码就简单多了:

Starting from version 2.6, PyCrypto can import also RsaPublicKey ASN.1 objects. The code is then much simpler:

from Crypto.PublicKey import RSA
from base64 import b64decode

key64 = b'MIGJAoGBAJNrHWRFgWLqgzSmLBq2G89exgi/Jk1NWhbFB9gHc9MLORmP3BOCJS9k
onzT/+Dk1hdZf00JGgZeuJGoXK9PX3CIKQKRQRHpi5e1vmOCrmHN5VMOxGO4d+znJDEbNHOD
ZR4HzsSdpQ9SGMSx7raJJedEIbr0IP6DgnWgiA7R1mUdAgMBAAE='

keyDER = b64decode(key64)
keyPub = RSA.importKey(keyDER)

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