libssh2_userau...ckey_frommemory(3)

✨ libssh2_userauth_publickey_frommemory — bestie edition ✨

okay so this one lives in the libssh2 manual, and it's literally about logging into a session with a public key that you're holding in memory. no files on disk, no drama, just vibes and buffers 💅

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🌸 NAME 🌸

libssh2_userauth_publickey_frommemory — authenticate a session with a public key, read from memory

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🎀 SYNOPSIS 🎀

#include <libssh2.h>

int
libssh2_userauth_publickey_frommemory(LIBSSH2_SESSION *session,
                                      const char *username,
                                      size_t username_len,
                                      const char *publickeydata,
                                      size_t publickeydata_len,
                                      const char *privatekeydata,
                                      size_t privatekeydata_len,
                                      const char *passphrase);

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💖 DESCRIPTION 💖

so here's the tea, the whole squad of arguments, one by one:

• session — Session instance as returned by libssh2_session_init_ex(3). this is your main character, the session you're doing all of this for 🫶
• username — Remote user name to authenticate as. who you're being on the other side ✨
• username_len — Length of username. yes bestie, you have to tell it how long the name is, we don't guess here 💀
• publickeydata — Buffer containing the contents of a public key file. the public key, just chilling in memory 🎀
• publickeydata_len — Length of public key data.
• privatekeydata — Buffer containing the contents of a private key file. the secret one, keep it safe 🙈
• privatekeydata_len — Length of private key data.
• passphrase — Passphrase to use when decoding private key file. iykyk 🔐

and the actual plot: this function attempts public key authentication using either a public key file or a PEM encoded private key file that's stored in memory. no disk, no touching grass.

• when you provide a private key, the public key is automatically extracted from it. the function does the work for you, iconic behavior fr fr 👑
• when you provide both, the passed public key takes precedence. so the public key you hand over is the one that wins, no cap.

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🔥 RETURN VALUE 🔥

Return 0 on success or negative on failure. it returns LIBSSH2_ERROR_EAGAIN when it would otherwise block. and listen — while LIBSSH2_ERROR_EAGAIN is a negative number, it is not really a failure per se. it's just the vibe check saying "try again later" 😌 so don't panic.

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💀 ERRORS 💀

• LIBSSH2_ERROR_ALLOC — An internal memory allocation call failed. the memory said no 😭
• LIBSSH2_ERROR_SOCKET_SEND — Unable to send data on socket.
• LIBSSH2_ERROR_SOCKET_TIMEOUT —
• LIBSSH2_ERROR_PUBLICKEY_UNVERIFIED — The username/public key combination was invalid.
• LIBSSH2_ERROR_AUTHENTICATION_FAILED — Authentication using the supplied public key was not accepted.

ok so quick heads up: LIBSSH2_ERROR_SOCKET_TIMEOUT shows up with no description in the original, so i'm not gonna invent one for you. it's giving mystery ✨

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🌈 AVAILABILITY 🌈

libssh2_userauth_publickey_frommemory was added in libssh2 1.6.0.

Supported with OpenSSL, WinCNG, mbedTLS, OS/400 crypto backends. so like, a whole friend group of crypto backends, we love to see it 🦋

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👑 SEE ALSO 👑

• libssh2_session_init_ex(3)

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and that's the whole page bestie, go forth and authenticate 🧚

this little love letter came to you from the libssh2 manual, dated 1 Sep 201 (yes, that's exactly how it's written, i don't make the rules 💀). mwah, go slay 💖✨🎀