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Made key exchange algorithm details more explicit #184

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Made key exchange algorithm details more explicit #184

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5de0aa3
Improve meaning of tx and rx keys in the algo details
Auresium Aug 14, 2025
8891845
Add some line breaks
Auresium Aug 14, 2025
db29a3f
Make naming convention consistent with the rest of the document
Auresium Aug 14, 2025
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6 changes: 4 additions & 2 deletions key_exchange/README.md
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Expand Up @@ -107,9 +107,11 @@ The shared secret key `rx` should be used by the server to receive data from the

## Algorithm details

Let `p.n` be the `crypto_scalarmult_curve25519_BYTES` byte output of the X25519 key exchange operation. The 512-bit output of `BLAKE2B-512` is split into two 256-bit keys `rx` and `tx`.
Let `p.n` be the `crypto_scalarmult_curve25519_BYTES` byte output of the X25519 key exchange operation. The 512-bit output of `BLAKE2B-512` is split into two 256-bit keys `client_rx` and `client_tx`.

`rx || tx = BLAKE2B-512(p.n || client_pk || server_pk)`
`client_rx = server_tx` and `client_tx = server_rx`.

`client_rx || client_tx = BLAKE2B-512(p.n || client_pk || server_pk)`

## Notes

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