Generate SSH keypair form PHP

Question

I want to generate ssh keypair from php can anyone please guide me how to do it? I have tried the shell_exec but the shell asks questions so that command does not work. I would like to specify filename and path in which to put the keys after generation.

Solution 1

This is based on Converting an OpenSSL generated RSA public key to OpenSSH format (PHP). Thanks shevron.

<?php
$rsaKey = openssl_pkey_new(array( 
              'private_key_bits' => 1024, 
              'private_key_type' => OPENSSL_KEYTYPE_RSA));

$privKey = openssl_pkey_get_private($rsaKey); 
openssl_pkey_export($privKey, $pem); //Private Key
$pubKey = sshEncodePublicKey($rsaKey); //Public Key

$umask = umask(0066); 
file_put_contents('/tmp/test.rsa', $pem); //save private key into file
file_put_contents('/tmp/test.rsa.pub', $pubKey); //save public key into file

print "Private Key:\n $pem \n\n";
echo "Public key:\n$pubKey\n\n";

function sshEncodePublicKey($privKey) {
    $keyInfo = openssl_pkey_get_details($privKey);
    $buffer  = pack("N", 7) . "ssh-rsa" .
    sshEncodeBuffer($keyInfo['rsa']['e']) . 
    sshEncodeBuffer($keyInfo['rsa']['n']);
    return "ssh-rsa " . base64_encode($buffer);
}

function sshEncodeBuffer($buffer) {
    $len = strlen($buffer);
    if (ord($buffer[0]) & 0x80) {
        $len++;
        $buffer = "\x00" . $buffer;
    }
    return pack("Na*", $len, $buffer);
}
?>

Solution 2

I would use phpseclib, a pure PHP RSA implementation:

<?php
include('Crypt/RSA.php');

$rsa = new Crypt_RSA();

$rsa->setPublicKeyFormat(CRYPT_RSA_PUBLIC_FORMAT_OPENSSH);

extract($rsa->createKey());
echo "$publickey\r\n\r\n$privatekey";
?>

Sample output:

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAAAgQCqGKukO1De7zhZj6+H0qtjTkVxwTCpvKe4eCZ0FPqri0cb2JZfXJ/DgYSF6vUpwmJG8wVQZKjeGcjDOL5UlsuusFncCzWBQ7RKNUSesmQRMSGkVb1/3j+skZ6UtW+5u09lHNsj6tQ51s1SPrCBkedbNf0Tp0GbMJDyR4e9T04ZZw== phpseclib-generated-key

-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----

Source: http://phpseclib.sourceforge.net/rsa/examples.html#openssh

Solution 3

Has anybody tried this?

ssh-keygen -q -N place_your_passphrase_here -t rsa -f ~/.ssh/id_rsa

It's worked for me

Solution 4

Check the manpage of ssh-keygen to find out how to execute it without any prompts.

http://linux.die.net/man/1/ssh-keygen

Solution 5

This code uses only built-in PHP openssl functions.

It generates keys in a portable PEM format, suitable for use with most 3rd party software.

<?php

function generateRsaKeyPair(array $config = []): array
{
  $config = array_merge([
    'digest_alg' => 'sha512',
    'private_key_bits' => 2048,
    'private_key_type' => OPENSSL_KEYTYPE_RSA,
  ], $config);

  // Create the keypair
  $key = openssl_pkey_new($config);
  if (!$key) {
    throw new RuntimeException('Unable to generate RSA key pair');
  }

  // Get private key
  openssl_pkey_export($key, $private);
  if (!$private) {
    throw new RuntimeException('Unable to extract private key');
  }

  // Get public key
  $public = openssl_pkey_get_details($key)['key'] ?? null;
  if (!$public) {
    throw new RuntimeException('Unable to extract public key');
  }

  // Free key from memory
  openssl_pkey_free($key);

  // Return both keys
  return compact('public', 'private');
}

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Comments

[adityap]

it seems that -q option silent the ssh-keygen but then how would i specify the filename and the directory??

[symcbean]

From the link provided by ThiefMaster: "ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile] " or use proc_open() to handle interactive I/O

[adityap]

got it working... with this command ssh-keygen -f /path/to/file -N ''

[am1]

I'm trying to use the built-in Openssl functions to generate a ED25519 keypair, but it's not supported right now, or?

[mistiry]

This worked perfectly. I increased the private_key_bits to 4096 though.

[Firewizz]

Excellent, this worked for me to overcome the "Enter file in which to save the key" question, thanks.