Objective-C

SFTP Set Allowed Algorithms

See more SFTP Examples

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

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

Objective-C

#import <CkoSFtp.h>
#import <CkoJsonObject.h>
#import <NSString.h>

BOOL success = NO;

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

CkoSFtp *sftp = [[CkoSFtp alloc] init];

CkoJsonObject *json = [[CkoJsonObject alloc] init];

//  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.
//  -------------------------------------------------------------------------------------------------------------------------------------------
NSString *allowed_kex = @"curve25519-sha256@libssh.org,ecdh-sha2-nistp256";
NSString *allowed_hostKey = @"ssh-ed25519,ecdsa-sha2-nistp256";
NSString *allowed_cipher = @"chacha20-poly1305@openssh.com,aes256-ctr";
NSString *allowed_mac = @"hmac-sha2-256,hmac-sha2-512";

[json UpdateString: @"kex" value: allowed_kex];
[json UpdateString: @"hostKey" value: allowed_hostKey];
[json UpdateString: @"cipher" value: allowed_cipher];
[json UpdateString: @"mac" value: allowed_mac];
[sftp SetAllowedAlgorithms: json];

int port = 22;
success = [sftp Connect: @"example.com" port: [NSNumber numberWithInt: port]];
if (success != YES) {
    NSLog(@"%@",sftp.LastErrorText);
    return;
}

NSLog(@"%@",@"Connected.");

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