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Asymmetric RSA encryption using pycrypto

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Asymmetric encryption has the advantage that a message can be encrypted without exchanging a secret key with the recipient of the message. The sender merely needs to know the recipients public key, this allows encrypting the message in such a way that only the designated recipient (who has the corresponding private key) can decrypt it. Currently, a third-party module like pycrypto is required for this functionality. 

from Crypto.Cipher import PKCS1_OAEP
from Crypto.PublicKey import RSA

message = b'This is a very secret message.'

with open('pubkey.pem', 'rb') as f:
    key = RSA.importKey(f.read())
cipher = PKCS1_OAEP.new(key)
encrypted = cipher.encrypt(message)

The recipient can decrypt the message then if they have the right private key: 

with open('privkey.pem', 'rb') as f:
    key = RSA.importKey(f.read())
cipher = PKCS1_OAEP.new(key)
decrypted = cipher.decrypt(encrypted)

Note: The above examples use PKCS#1 OAEP encryption scheme. pycrypto also implements PKCS#1 v1.5 encryption scheme, this one is not recommended for new protocols however due to known caveats.

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Security and Cryptograhy:
* Security and Cryptography
* Secure Password Hashing
* Calculating a Message Digest
* Available Hashing Algorithms
* File Hashing
* Symmetric encryption using pycrypto
* Generating RSA signatures using pycrypto
* Asymmetric RSA encryption using pycrypto
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