review-claim / decrypt.py
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from Crypto.PublicKey import RSA
from Crypto.Cipher import AES, PKCS1_OAEP
file_in = open("encrypted_data.bin", "rb")
private_key = RSA.import_key(open("private.pem").read())
enc_session_key, nonce, tag, ciphertext = \
[ file_in.read(x) for x in (private_key.size_in_bytes(), 16, 16, -1) ]
# Decrypt the session key with the private RSA key
cipher_rsa = PKCS1_OAEP.new(private_key)
session_key = cipher_rsa.decrypt(enc_session_key)
# Decrypt the data with the AES session key
cipher_aes = AES.new(session_key, AES.MODE_EAX, nonce)
data = cipher_aes.decrypt_and_verify(ciphertext, tag)
print(data.decode("utf-8"))