Array of unsigned char to string [closed]

Question

In my quest for a single header encryption library for c++ I found this github repo that uses AES with CBC mode to encrypt a std::string into a vector of unsigned char in the example provided in the repo this

 const unsigned char iv[16] = { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, };

initialization vector was used, now the encrypted data is ready to be sent to the api with the endpoint /data that accepts data in JSON format

{"data":"encrypted-data"}

and decryptes it for later use

the server where the data is sent is written in python and uses the following lines to decrypt the data

 obj2 = AES.new('EncryptionKey128'.encode("utf8"), AES.MODE_CBC, 'This is an IV456'.encode("utf8")) result = obj2.decrypt(phrase) print (result)

how to convert the iv to a string to use on the server side

if tried looping over the items in

lst = [ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F] for item in lst: item = item.replace('0x','') bytes_object = bytes.fromhex(item) ascii_string = bytes_object.decode("utf-8")

but this create an iv that is larger than 16 chars

Goal behind this is to encrypt a string with AES and send it to a python server to be decrypted for the sake of this example both keys will be hardcoded in the server and the client

the elements in the lst list are all hexadecimal values, then why do you remove 0x, comment out this line item = item.replace('0x','') — Anand Sowmithiran
– Anand Sowmithiran, Commented Dec 31, 2021 at 11:46
item = item.replace('0x','') I heavily doubt, this will work as intended. — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Dec 31, 2021 at 11:47
You want to convert the unsigned char array iv into an UTF-8 string? And you want to do it in Python? The chr function creates an character out of a number. — Sebastian
– Sebastian, Commented Dec 31, 2021 at 11:49

user8143588 · Accepted Answer · 2021-12-31 11:46:20Z

2

The usual approach for these cases is to convert those bytes to base64 before sending and sticking that resulting string in the JSON request. On the server side, your python code needs to decode the resulting base64 to convert it back to bytes.

answered Dec 31, 2021 at 11:46

user8143588

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2 Comments

ahmad Over a year ago

yes this is done to the encrypted data but I want to convert the iv to a string to use in the decrypting part on the server side

Sebastian Over a year ago

To insert in the program code there?

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