What is the best way to encode string by public-key in python

Is there any way to encode string by publi开发者_StackOverflowc-key?

I found two packages, pycrypto and m2crypto. But I can not find how to use them.

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To encode a string using public key:

#!/usr/bin/env python 
from M2Crypto import RSA, X509

x509 = X509.load_cert("recipient_cert.pem")
rsa = x509.get_pubkey().get_rsa()
print rsa.public_encrypt("your string to encrypt", RSA.pkcs1_oaep_padding)