How encrypt email with a GnuPG public key ? [ solved ] (programming.dev)

submitted 3 days ago* (last edited 2 days ago) by Rick_C137@programming.dev to c/python@programming.dev

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Hi,

I'm already using

from smtplib import SMTP_SSL
from email.message import EmailMessage

To send emails.

Now I would like to be able to encrypt them with the public key of the recipient. ( PublicKey.asc )

an A.I provide me this

import smtplib
from email.message import EmailMessage
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.ciphers.aead import AESGCM

# Load the ECC public key from the .asc file
with open('recipient_public_key.asc', 'rb') as key_file:
    public_key_bytes = key_file.read()
public_key = ec.EllipticCurvePublicKey.from_public_bytes(
    ec.SECP384R1(),
    public_key_bytes
)

# Create the email message
msg = EmailMessage()
msg.set_content('This is the encrypted email.')
msg['Subject'] = 'Encrypted Email'
msg['From'] = 'you@example.com'
msg['To'] = 'recipient@example.com'

# Encrypt the email message using the ECC public key
nonce = bytes.fromhex('000102030405060708090a0b0c0d0e0f')
cipher = AESGCM(public_key.public_key().secret_key_bytes)
ciphertext = cipher.encrypt(nonce, msg.as_bytes(), None)

# Send the encrypted email
server = smtplib.SMTP('smtp.example.com')
server.send_message(msg, from_addr='you@example.com', to_addr='recipient@example.com')
server.quit()

# Save the encrypted email to a file
with open('encrypted_email.bin', 'wb') as f:
    f.write(ciphertext)

I like the approach, only one "low level" import cryptography

but the code seem wrong. if the body has been encrypted as ciphertext I don't see this one included while sending the email.

How are you doing it ? or do you have good tutorial, documentations ? because I found nothing "pure and simple" meaning not with of unnecessary stuff.

Thanks.

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[-] AsudoxDev@programming.dev 1 points 3 days ago* (last edited 3 days ago)

You can use a gnupg library for python and then use the recipient's public key to encrypt your email before sending it?

[-] Rick_C137@programming.dev 2 points 3 days ago* (last edited 3 days ago)

instead of using a library I can directly use subprocess with gnupg but in both case it seem gnupg require to import the public key to the keyring !? I don't want that.