Converting C uint8_t to python utf_16_be

Question

I am trying to port a python script that use scrypt to generate a password.

import pylibscrypt scrypt = pylibscrypt.scrypt password = 'test123'.encode("utf_16_be", "replace") salt = '384eaed91035763e'.decode('hex') key = scrypt(password, salt, 16384, 8, 1, 32) print (key.encode('hex'))

Result should be: 9f2117416c7b2de9419a81c4625a28e40c16ac92aaa3000bb2c35844b3839eb1

In C, I use libsodium crypto_pwhash_scryptsalsa208sha256_ll() function.

If I try to pass the password from that variable:

const uint8_t password[] = "test123";

I am not getting the same key. I tried to remove ".encode("utf_16_be", "replace")" from the python script and then I get the same result.

So how can I convert my C variable to be the same as the python variable?

EDIT: The original software is in Java and seems to encode strings as UTF-16 big endian. Now I need to encode a C string to the same format.

Why not encode it as ASCII? Is there a chance the password will contain any non-ascii characters? — Eugene Sh.
– Eugene Sh., Commented Feb 15, 2017 at 15:11
I think the python software must support unicode so this is why it is not ascii. — 01BTC10
– 01BTC10, Commented Feb 15, 2017 at 15:12
Since it is a password, you may restrict it to be ascii-only.. — Eugene Sh.
– Eugene Sh., Commented Feb 15, 2017 at 15:13
I am converting a python script to C and the problem is that if I use ascii then it doesn't work since it give a different key. — 01BTC10
– 01BTC10, Commented Feb 15, 2017 at 15:14
Well.. on Linux you can use iconv and friends to convert between encodings. — Eugene Sh.
– Eugene Sh., Commented Feb 15, 2017 at 15:17

Community · Accepted Answer · 2017-05-23 11:46:11Z

I found a solution inspired from: Create UTF-16 string from char*

 size_t uint8_t_UTF_16(uint8_t *input, uint8_t *output, size_t inlen) { size_t outlen = 0.0; for (size_t i = 0; i < inlen; i++) { if (isascii(input[i])) { output[i] = 0; output[i + 1] = input[i / 2]; i++; outlen += 2; } else { output[i] = input[i]; outlen += 0.5; } } return outlen; }

It does work but I'm not sure that this solution is safe.

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