---
name: "libssh2_userauth_publickey_fromfile_ex"
section: "3"
platform: "linux"
package: "libssh2"
version: "1.11.1-7"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/libssh2_userauth_publickey_fromfile_ex"
---

# libssh2\_userauth\_publickey\_fromfile\_ex(3)

authenticate a session with a public key, read from a file

## NAME

libssh2\_userauth\_publickey\_fromfile\_ex - authenticate a session with a public key, read from a file

## SYNOPSIS

```
#include <libssh2.h>
int
libssh2_userauth_publickey_fromfile_ex(LIBSSH2_SESSION *session,
                                       const char *username,
                                       unsigned int username_len,
                                       const char *publickey,
                                       const char *privatekey,
                                       const char *passphrase);
```

## DESCRIPTION

*session* - Session instance as returned by **[libssh2\_session\_init\_ex(3)](/libssh2_session_init_ex/3.md)**

*username* - Pointer to user name to authenticate as.

*username\_len* - Length of *username*.

*publickey* - Path name of the public key file. (e.g. /etc/ssh/hostkey.pub). If libssh2 is built against OpenSSL, this option can be set to NULL.

*privatekey* - Path name of the private key file. (e.g. /etc/ssh/hostkey)

*passphrase* - Passphrase to use when decoding *privatekey*.

Attempt public key authentication using either a public key file or a PEM encoded private key file stored on disk. When providing a private key, the public key is automatically extracted from it. When providing both, the passed public key takes precedence.

## RETURN VALUE

Return 0 on success or negative on failure. It returns LIBSSH2\_ERROR\_EAGAIN when it would otherwise block. While LIBSSH2\_ERROR\_EAGAIN is a negative number, it is not really a failure per se.

## ERRORS

*LIBSSH2\_ERROR\_FILE* - An issue opening, reading or parsing the disk file.

*LIBSSH2\_ERROR\_ALLOC* - An internal memory allocation call failed.

*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.

## SEE ALSO

**[libssh2\_session\_init\_ex(3)](/libssh2_session_init_ex/3.md)**