54 lines
2.0 KiB
Python
54 lines
2.0 KiB
Python
from tinyec import registry
|
|
from Crypto.Cipher import AES
|
|
import hashlib, secrets, binascii
|
|
|
|
def encrypt_AES_GCM(msg, secretKey):
|
|
aesCipher = AES.new(secretKey, AES.MODE_GCM)
|
|
ciphertext, authTag = aesCipher.encrypt_and_digest(msg)
|
|
return (ciphertext, aesCipher.nonce, authTag)
|
|
|
|
def decrypt_AES_GCM(ciphertext, nonce, authTag, secretKey):
|
|
aesCipher = AES.new(secretKey, AES.MODE_GCM, nonce)
|
|
plaintext = aesCipher.decrypt_and_verify(ciphertext, authTag)
|
|
return plaintext
|
|
|
|
def ecc_point_to_256_bit_key(point):
|
|
sha = hashlib.sha256(int.to_bytes(point.x, 32, 'big'))
|
|
sha.update(int.to_bytes(point.y, 32, 'big'))
|
|
return sha.digest()
|
|
|
|
curve = registry.get_curve('brainpoolP256r1')
|
|
|
|
def encrypt_ECC(msg, pubKey):
|
|
ciphertextPrivKey = secrets.randbelow(curve.field.n)
|
|
sharedECCKey = ciphertextPrivKey * pubKey
|
|
secretKey = ecc_point_to_256_bit_key(sharedECCKey)
|
|
ciphertext, nonce, authTag = encrypt_AES_GCM(msg, secretKey)
|
|
ciphertextPubKey = ciphertextPrivKey * curve.g
|
|
return (ciphertext, nonce, authTag, ciphertextPubKey)
|
|
|
|
def decrypt_ECC(encryptedMsg, privKey):
|
|
(ciphertext, nonce, authTag, ciphertextPubKey) = encryptedMsg
|
|
sharedECCKey = privKey * ciphertextPubKey
|
|
secretKey = ecc_point_to_256_bit_key(sharedECCKey)
|
|
plaintext = decrypt_AES_GCM(ciphertext, nonce, authTag, secretKey)
|
|
return plaintext
|
|
|
|
msg = b'Text to be encrypted by ECC public key and ' \
|
|
b'decrypted by its corresponding ECC private key'
|
|
print("original msg:", msg)
|
|
privKey = secrets.randbelow(curve.field.n)
|
|
pubKey = privKey * curve.g
|
|
|
|
encryptedMsg = encrypt_ECC(msg, pubKey)
|
|
encryptedMsgObj = {
|
|
'ciphertext': binascii.hexlify(encryptedMsg[0]),
|
|
'nonce': binascii.hexlify(encryptedMsg[1]),
|
|
'authTag': binascii.hexlify(encryptedMsg[2]),
|
|
'ciphertextPubKey': hex(encryptedMsg[3].x) + hex(encryptedMsg[3].y % 2)[2:]
|
|
}
|
|
print("encrypted msg:", encryptedMsgObj)
|
|
|
|
decryptedMsg = decrypt_ECC(encryptedMsg, privKey)
|
|
print("decrypted msg:", decryptedMsg)
|