reinterpret_cast<byte*> truncating to 8

[Devharsh Trivedi]

I am trying to convert a std::string to cryptopp::byte like this

const byte* pt = reinterpret_cast<const byte*>(&alert[0]);

but it doesn't copy the full string, as confirmed by sizeof

sizeof(alert) = 24

sizeof(pt) = 8

why is it truncating to first 8 bytes?

[Jeffrey Walton]

pt is a pointer. A pointer on x86_64 is 8 bytes.

Jeff

[Devharsh Trivedi]

Thank you for your reply.

I am following this example - https://www.cryptopp.com/wiki/XChaCha20Poly1305

and trying to use std::string instead of byte

instead of using byte array for ct like this

dec.DecryptAndVerify(rt, mac, sizeof(mac), iv, sizeof(iv), aad, sizeof(aad), ct, sizeof(ct));

I am trying to use string like this

std::string cipher;

StringSource(ct, sizeof(ct), true, new HexEncoder(new StringSink(cipher)));

const byte* xct = reinterpret_cast<const byte*>(cipher.data());

dec.DecryptAndVerify(rt, mac, sizeof(mac), iv, sizeof(iv), aad, sizeof(aad), xct, sizeof(xct));

but this doesn't seem to work

[Jeffrey Walton]

On Tuesday, March 9, 2021 at 3:45:47 PM UTC-5 devhar...@gmail.com wrote:

Thank you for your reply.

I am following this example - https://www.cryptopp.com/wiki/XChaCha20Poly1305

and trying to use std::string instead of byte

instead of using byte array for ct like this

dec.DecryptAndVerify(rt, mac, sizeof(mac), iv, sizeof(iv), aad, sizeof(aad), ct, sizeof(ct));

I am trying to use string like this

std::string cipher;

StringSource(ct, sizeof(ct), true, new HexEncoder(new StringSink(cipher)));

const byte* xct = reinterpret_cast<const byte*>(cipher.data());

dec.DecryptAndVerify(rt, mac, sizeof(mac), iv, sizeof(iv), aad, sizeof(aad), xct, sizeof(xct));

 dec.DecryptAndVerify(rt, mac, sizeof(mac), iv, sizeof(iv), aad, sizeof(aad), xct, cipher.size());

Jeff

[Devharsh Trivedi]

cipher.size() doesn't help :/

the problem is not related to size but the xct pointer itself

however, if I do something similar with mac, it works

const byte* xmac = reinterpret_cast<const byte*>(strMac.data());

dec.DecryptAndVerify(rt, xmac, sizeof(xmac), iv, sizeof(iv), aad, sizeof(aad), ct, sizeof(ct));

the issue arises when I try to work with xct