Hey guys, Wireguard data packets have a 1 byte type, a 4 byte index, an 8 byte nonce, the ciphertext, and then a 16 byte auth tag. Having 13 bytes in the beginning means that when we do in-place decryption, the plaintext winds up starting at an odd-byte, transferring misalignment down to the rest of the stack.
Now, in my testing on alignment-sensitive MIPS boxes, I've only had alignment exceptions with this regarding the first byte, which is the version number of the IP header. Since this is just a single byte, the alignment doesn't actually matter. But in practice, the compiler generates a 16-bit load instead of an 8-bit load, which sucks. I may be able to work around this though. Beyond that, I haven't actually observed exceptions from elsewhere in the stack regarding misalignment. So, how much of a problem do you suppose this is? Would it be worthwhile to stick an _extra byte_ in the header, just to get even alignment? Or an extra three bytes to get 16-byte alignment? Or do you suppose this isn't really worth the bloat and MTU loss? Just something to think about... Jason _______________________________________________ WireGuard mailing list [email protected] https://lists.zx2c4.com/mailman/listinfo/wireguard
