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