Openssl and PHP

Question

Im trying to load a private key generated by the openssl cli tool with PHP. I used the following command and PHP code:

openssl genrsa -des3 4096 -out private.key

if (!($key = openssl_pkey_get_private("file://private.key", "password")));
{
      return false;
}

I'm sure the password is correct and the file is also PEM formatted, but it keeps returning false. What am I doing wrong?

Thanks in advance, Jori.

Answer 1

Please refer to next URL.

https://www.php.net/manual/en/function.openssl-pkey-get-private.php

To narrow down your issue, please use same directory for your php file and key file and try this working code.

Working code

$keyfile="file://".__DIR__.DIRECTORY_SEPARATOR."key.pem"; //absolute path
$key = openssl_pkey_get_private($keyfile);

if ($key === false) {
    var_dump(openssl_error_string());
}else{
    var_dump($key);
}

The following might be an issue.

1. Path

Following path styles should work.

$keyfile="file:///home/john/php/key.pem"; // unix absoulute path
$keyfile="file://C:\\users\\john\\php\\key.pem"; // windows absoulute path
$keyfile="file://".__DIR__.DIRECTORY_SEPARATOR."key.pem"; //absoulute path for unix, windows
$keyfile="file://key.pem"; // relative path, unix, windows, (php,key files in same directory)

$key = openssl_pkey_get_private($keyfile);

If path does not exist, error will be like

"error:02001002:system library:fopen:No such file or directory"

2. Web environment

   Check your web root and web user access permission to the folder and key file.

   To reduce issues, test it on php build-in web server env rather than WAMP env.

>php -S localhost:80

3. Corrupted key file

saved as certain type which include whitespaces. This can occur error like next.

"error:0906D06C:PEM routines:PEM_read_bio:no start line"

in my case, key file was saved as UTF-8 with BOM(whitespaces)

DEBUG key file 1 - READ FROM VARIABLE

This code should work. I got key file from http://micmap.org/php-by-example/en/function/openssl_pkey_get_private

Please replace $str to yours.

$str = <<<EOF
-----BEGIN RSA PRIVATE KEY----- 
MIIEogIBAAKCAQEA0llCeBjy18RylTdBih9GMUSZIC3GzeN0vQ9W8E3nwy2jdeUn 
H3GBXWpMo3F43V68zM2Qz5epRNmlLSkY/PJUfJIC8Yc1VEokT52q87hH/XJ5eS8h 
eZnjuSlPAGi8oZ3ImVbruzV7XmlD+QsCSxJW7tBv0dqJ71e1gAAisCXK2m7iyf/u 
l6rT0Zz0ptYH4IZfwc/hQ9JcMg69uM+3bb4oBFsixMmEQwxKZsXk3YmO/YRjRbay 
+6+79bSV/frW+lWhknyGSIJp2CJArYcOdbK1bXx1dRWpbNSExo7dWwuPC0Y7a5AE 
eoZofieQPPBhXlp1hPgLYGat71pDqBjKLvF5GwIDAQABAoIBACPItYsSy3UzYT7L 
OKYTrfBBuD8GKpTqBfkHvAWDa1MD15P92Mr7l0NaCxGfAy29qSa6LdFy/oPM9tGY 
9TxKyV6rxD5sfwEI3+Z/bw6pIe4W5F1eTDaQnHHqehsatkRUQET9yXp+na8w/zRF 
0C0PQKS95tfvcpm59RGCdGQ8+aZw+cIy/xez75W8IS/hagMxe7xYPjpkOkSCCEJU 
zmbVq6AyWodASV0p4H9p8I+c0vO2hJ/ELJ167w6T+2/GlZg979rlyHoTW8jK2BbG 
IRGaPo+c2GANXa686tdpbkPd6oJliXwBSNolxmXShvlveBbPFAJJACzCmbXNj9kH 
6/K+SWkCgYEA7FNudcTkRPV8TzKhJ1AzDjw3VcnraYhY8IlNxbk7RVHLdkoUtwk/ 
mImeBlEfCoz9V+S/gRgeQ+1Vb/BCbS24+bN/+IGoNRFMRcOieFt6lQUpj7a9NeSo 
IEclGgUiU7QR3xH73SB4GC3rgSPeHJhJZC5EJq5TzYjXTPGPpBD3zicCgYEA49wz 
zfMDYIH8h4L65r/eJYIbLwpvgktgaYvhijO3qfZSWW+Y19jCBn55f65YOhPGQBHA 
my0f+tVxFNZ/OupbrAIIzogxlCIYHNBawDhoHN/sB3/lSBAjifySNLyRlA62oA0w 
wXvXVLVWMa3aXim3c9AlnLF1fHwcvwpOKSfdye0CgYBb1mBKq+T5V1yjek1d9bCh 
i40FbZ5qOG43q2Ppvn3mBk9G/KroJlPsdy5NziB9/SRGj8JL7I92Xjihc4Cc5PPJ 
NZQ5gklXtg0p30i39PTCDGuGScFlvCIJyRwF7JDWblezlE2INSH2Y4HtgX7DJfr/ 
T2t0jLJMYS0p3YWwgFeMaQKBgHUIe/8y6zAdc5QynSX5tGL1gXrW1FFK39k2RICU 
cag1YTSYkhuDNJzbRxJifORPlcsAkzngooVWLb+zMCQVjUI6xUU3RKe+Hz5lccc6 
8ZarGHL9qMkrqOVNudamZ+tw5zIrtDgcoIvcm8nmbrtgl94/MaJar2ph4O3qoByZ 
Ylw9AoGAIdS79s0VKkj4VVXqK47ZcI7jGL4V4C8ujU8YcMNV88xwCoDg9ZIFprWA 
P5p/cnvj6aHnqL58XiH0+bE0Lt3J+U6N6JelQQevgBHooMFh4FpDXcVda7xB3rK3 
woqbi8fNhr827H2maxIZPtVG95/mvR4k5z1Jrdnr34ZUmtC6U5Q= 
-----END RSA PRIVATE KEY-----
EOF;

$key = openssl_pkey_get_private($str);
if ($key === false) {
    var_dump(openssl_error_string());
}else{
    var_dump($key);
}

OUTPUT

resource(4) of type (OpenSSL key)

DEBUG key file 2 - READ FROM FILE

copy your key strings($str) to key file like "key.pem".

$str = <<<EOF
-----BEGIN RSA PRIVATE KEY----- 
...YOUR KEY STINGS HERE...
-----END RSA PRIVATE KEY-----
EOF;

$str2 = file_get_contents("key.pem");

$len1 = strlen ($str);
$len2 = strlen ($str2);
if($len1 !== $len2) echo "File has been corrupted.";

$key = openssl_pkey_get_private($str2);

if ($key === false) {
    var_dump(openssl_error_string());
}else{
    var_dump($key);
}

Answer 2

Please note that file://path/to/file.pem in documentation means file protocol + file path. In UNIX like OS, that is something like file:///rsa_private_key.pem. There is THREE slashes in the path string, not TWO. And file:// cannot be omitted.

Answer 3

It is a lot easier to just put the key in a var:

$public = "-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDfmlc2EgrdhvakQApmLCDOgP0n
NERInBheMh7J/r5aU8PUAIpGXET/8+kOGI1dSYjoux80AuHvkWp1EeHfMwC/SZ9t
6rF4sYqV5Lj9t32ELbh2VNbE/7QEVZnXRi5GdhozBZtS1gJHM2/Q+iToyh5dfTaA
U8bTnLEPMNC1h3qcUQIDAQAB
-----END PUBLIC KEY-----";

$private = "-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----";

if (!$privateKey = openssl_pkey_get_private($private)) die('Loading Private Key failed');
if (!$publicKey = openssl_pkey_get_public($public)) die('Loading Public Key failed');

I'll also include a small encode / decode example:

$encrypted = '';
$decrypted = '';

$plaintext = 'This is just some text to encrypt';

echo '<p>$plaintext = ' . $plaintext . '<p>';

if (!openssl_public_encrypt($plaintext, $encrypted, $publicKey))    die('Failed to encrypt data');

echo '<p>$encrypted = ' . $encrypted . '<p>';

if (!openssl_private_decrypt($encrypted, $decrypted, $privateKey))  die('Failed to decrypt data');

echo '<p>$decrypted = ' . $decrypted . '<p>';

Or just in case you could generate a key with php:

$NEW_KEY = openssl_pkey_new(array(
    'private_key_bits' => 1024,
    'private_key_type' => OPENSSL_KEYTYPE_RSA,
        ));

openssl_pkey_export_to_file($NEW_KEY, 'private.key');

$NEW_KEY_DETAILS = openssl_pkey_get_details($NEW_KEY);
file_put_contents('public.key', $NEW_KEY_DETAILS['key']);

openssl_free_key($NEW_KEY);