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From: Hristo Georgiev <hristo.metal@gmail.com>
To: wireguard@lists.zx2c4.com
Subject: Nonce in out-of-order messages
Date: Wed, 24 Jul 2019 13:05:58 +0300	[thread overview]
Message-ID: <E6BE60A6-0A9F-4A45-9FCE-155410ECDC6F@gmail.com> (raw)

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?

Thank you,
Hristo
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             reply	other threads:[~2019-08-25 15:37 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-24 10:05 Hristo Georgiev [this message]
2019-08-25 15:56 ` Nonce in out-of-order messages Jason A. Donenfeld
2019-09-01  8:10   ` Hristo Georgiev

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