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puttyprivate-key

Why does PuTTY use its own private key format when log into SSH server?

Just a little bit curious, why PuTTY use its own version of private key format to do SSH?

Solution

  • The author of PuTTY gives two main reasons for having the custom key format on this page.

    In short:

    • PuTTY's format stores the public half of the key in plaintext, which allows PuTTY to send the public key to the server automatically.

    • The key is fully tamperproofed with the help of a Message Authentication Code.