On Sun, Aug 25, 2019 at 9:36 AM Hristo Georgiev <[email protected]> wrote: > > Hello > I’m working on file transfer protocol inspired by Noise and Wireguard over > UDP with static keys so the handshake pattern is going to be > Noise_IK_25519_ChaChaPoly_BLAKE2s or KK. In general i’m trying to follow > NoiseSocket spec but adapted to UDP and i was wondering where to place the > ‘nonce’ into packet to extend the protocol as described into p.11.4 in > NoiseProtocol spec > http://www.noiseprotocol.org/noise.html#out-of-order-transport-messages . So > I had a look into WireGuard implementation (which I use a lot in multiple > sites, mostly on EdgeRouters) > so what i found in noise.c line 445 message_decrypt: > > chacha20poly1305_decrypt(dst_plaintext, src_ciphertext, src_len, > hash, NOISE_HASH_LEN, > 0 /* Always zero for Noise_IK */, key)) > > Correct me if I’m mistaken, I’m not C programer nor cryptographer, I think > this zero here is the Nonce. If that’s the case what security sacrifices and > the chance for replay attacks are? > Would it be Ok if I also hardcode the Nonce to 0 in my implementation?
This isn't the nonce used as part of the transport object, but rather a single encryption/decryption that happens with a unique key as part of the handshake. It being zero is a natural consequence of the protocol flow. Don't hardcode a zero nonce in transport messages. _______________________________________________ WireGuard mailing list [email protected] https://lists.zx2c4.com/mailman/listinfo/wireguard
