(C) SSH Set Allowed Algorithms

See more SSH Examples

Demonstrates how to explicitly set the algorithms allowed in the SSH connection protocol.

Note: This example requires Chilkat v9.5.0.99 or greater.

Chilkat C/C++ Library Downloads
MS Visual C/C++ Linux/CentOS C/C++ Alpine Linux C/C++ MAC OS X C/C++	armhf/aarch64 C/C++ C++ Builder iOS C/C++ Android C/C++	Solaris C/C++ MinGW C/C++

#include <C_CkSsh.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkSsh ssh;
    HCkJsonObject json;
    const char *allowed_kex;
    const char *allowed_hostKey;
    const char *allowed_cipher;
    const char *allowed_mac;
    int port;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    ssh = CkSsh_Create();

    json = CkJsonObject_Create();

    // Here are the algorithms supported by Chilkat at the time this example was written (14-June-2024)

    // ---------------------------
    // SSH Key-Exchange Algorithms
    // ---------------------------
    // curve25519-sha256
    // curve25519-sha256@libssh.org
    // ecdh-sha2-nistp256
    // ecdh-sha2-nistp384
    // ecdh-sha2-nistp521
    // diffie-hellman-group14-sha256
    // diffie-hellman-group16-sha512
    // diffie-hellman-group18-sha512
    // diffie-hellman-group-exchange-sha256
    // diffie-hellman-group1-sha1
    // diffie-hellman-group14-sha1
    // diffie-hellman-group-exchange-sha1

    // ---------------------------
    // SSH Host Key Algorithms
    // ---------------------------
    // ssh-ed25519
    // ecdsa-sha2-nistp256
    // ecdsa-sha2-nistp384
    // ecdsa-sha2-nistp521
    // rsa-sha2-256
    // rsa-sha2-512
    // ssh-rsa
    // ssh-dss

    // ---------------------------
    // SSH Cipher Algorithms
    // ---------------------------
    // chacha20-poly1305@openssh.com
    // aes128-ctr
    // aes256-ctr
    // aes192-ctr
    // aes128-cbc
    // aes256-cbc
    // aes192-cbc
    // aes128-gcm@openssh.com
    // aes256-gcm@openssh.com
    // twofish256-cbc
    // twofish128-cbc
    // blowfish-cbc

    // ---------------------------
    // SSH MAC Algorithms
    // ---------------------------
    // hmac-sha2-256
    // hmac-sha2-512
    // hmac-sha2-256-etm@openssh.com
    // hmac-sha2-512-etm@openssh.com
    // hmac-sha1-etm@openssh.com
    // hmac-sha1
    // hmac-ripemd160
    // hmac-sha1-96
    // hmac-md5

    // Specify the allowed key-exchange, host-key, cipher (i.e. encryption), and mac (i.e. hash) algorithms allowed, in the order of preference.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    // Note: You typically should NOT explicitly set allowed algorithms.
    // By default, Chilkat orders algorithms according to best practices, and pays attention to vulnerabilities such as the "Terrapin Attack".
    // Hard-coding algorthims can make your application brittle and prone to breaking over a long period of time,
    // if a server (at some point in the future) changes its allowed algorithms, or if you connect to a different server,
    // such that the client (Chilkat) and server cannot find a set of mutually agreed-upon algorithms.
    // -------------------------------------------------------------------------------------------------------------------------------------------
    allowed_kex = "curve25519-sha256@libssh.org,ecdh-sha2-nistp256";
    allowed_hostKey = "ssh-ed25519,ecdsa-sha2-nistp256";
    allowed_cipher = "chacha20-poly1305@openssh.com,aes256-ctr";
    allowed_mac = "hmac-sha2-256,hmac-sha2-512";

    CkJsonObject_UpdateString(json,"kex",allowed_kex);
    CkJsonObject_UpdateString(json,"hostKey",allowed_hostKey);
    CkJsonObject_UpdateString(json,"cipher",allowed_cipher);
    CkJsonObject_UpdateString(json,"mac",allowed_mac);
    CkSsh_SetAllowedAlgorithms(ssh,json);

    port = 22;
    success = CkSsh_Connect(ssh,"example.com",port);
    if (success != TRUE) {
        printf("%s\n",CkSsh_lastErrorText(ssh));
        CkSsh_Dispose(ssh);
        CkJsonObject_Dispose(json);
        return;
    }

    printf("Connected.\n");

    // ....
    // ....


    CkSsh_Dispose(ssh);
    CkJsonObject_Dispose(json);

    }