OpenSSH 加入了 noise (keystroke timing obfuscation) 功能

在 Hacker News 上看到在 OpenSSH 裡加入 keystroke timing obfuscation 的功能：「Keystroke timing obfuscation added to ssh(1) (undeadly.org)」。

如同 commit log 裡面提到的，這個功能會想要故意沒事就送一些沒用的資料 (增加一些噪音)，降低從 side channel 被判讀的資訊量：

This attempts to hide inter-keystroke timings by sending interactive traffic at fixed intervals (default: every 20ms) when there is only a small amount of data being sent. It also sends fake “chaff” keystrokes for a random interval after the last real keystroke. These are controlled by a new ssh_config ObscureKeystrokeTiming keyword/

基於 OpenSSH 算是 SSH 這塊的 de-factor standard 了，接下來看其他家像是 Dropbear 會不會也實作？

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