Perl Requires Chilkat v9.5.0.99+
SFTP Set Allowed Algorithms

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

Chilkat2 Perl
use strict;
use warnings;
use Chilkat2;

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

my $sftp = Chilkat2::SFtp->new;

my $json = Chilkat2::JsonObject->new;

# 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.
# -------------------------------------------------------------------------------------------------------------------------------------------
my $allowed_kex = 'curve25519-sha256@libssh.org,ecdh-sha2-nistp256';
my $allowed_hostKey = 'ssh-ed25519,ecdsa-sha2-nistp256';
my $allowed_cipher = 'chacha20-poly1305@openssh.com,aes256-ctr';
my $allowed_mac = 'hmac-sha2-256,hmac-sha2-512';

$json->UpdateString('kex', $allowed_kex);
$json->UpdateString('hostKey', $allowed_hostKey);
$json->UpdateString('cipher', $allowed_cipher);
$json->UpdateString('mac', $allowed_mac);
$sftp->SetAllowedAlgorithms($json);

my $port = 22;
my $success = $sftp->Connect('example.com', $port);
if (!$success) {
    print $sftp->LastErrorText, "\n";
    exit;
}

print "Connected.\n";

# ....
# ....