How to load a public RSA key into Python-RSA from a file?

python openssl rsa pem

Amine Kerkeni · May 10, 2013 · Viewed 20.5k times · Source

I generated a private and a public key using OpenSSL with the following commands:

openssl genrsa -out private_key.pem 512
openssl rsa -in private_key.pem -pubout -out public_key.pem

I then tried to load them with a python script using Python-RSA:

import os
import rsa

with open('private_key.pem') as privatefile:
    keydata = privatefile.read()
privkey = rsa.PrivateKey.load_pkcs1(keydata,'PEM')

with open('public_key.pem') as publicfile:
    pkeydata = publicfile.read()

pubkey = rsa.PublicKey.load_pkcs1(pkeydata)

random_text = os.urandom(8)

#Generate signature
signature = rsa.sign(random_text, privkey, 'MD5')
print signature

#Verify token
try:
    rsa.verify(random_text, signature, pubkey)
except:
    print "Verification failed"

My python script fails when it tries to load the public key:

ValueError: No PEM start marker "-----BEGIN RSA PUBLIC KEY-----" found

Answer

If on Python3, You also need to open the key in binary mode, e.g:

with open('private_key.pem', 'rb') as privatefile:

How to load a public RSA key into Python-RSA from a file?

Answer

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