Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

 Chilkat Perl Module Downloads for Windows, Linux, and MAC OS X

use chilkat();

$pkey = new chilkat::CkPrivateKey();

#  Load the private key from an RSA PEM file:
$pkey->LoadPemFile("myKey.pem");

#  Get the private key in XML format:
$pkeyXml = $pkey->getXml();

$rsa = new chilkat::CkRsa();

#  Any string argument automatically begins the 30-day trial.
$success = $rsa->UnlockComponent("30-day trial");
if ($success != 1) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

#  Import the private key into the RSA component:
$success = $rsa->ImportPrivateKey($pkeyXml);
if ($success != 1) {
    print $rsa->lastErrorText() . "\r\n";
    exit;
}

#  OpenSSL uses BigEndian byte ordering:
$rsa->put_LittleEndian(0);

#  The resulting signature will be a Base64 string:
$rsa->put_EncodingMode("base64");

#  For simplicity, we're not loading
#  the data to be signed from a file.  We are instead simply
#  using a literal string value.
$strData = "This is the text to be signed.";

#  Hash the input using MD5, and then sign the hash:
#  Other valid hash algorithm choices are "md2" and "sha-1".
$base64Sig = $rsa->signStringENC($strData,"md5");

print $base64Sig . "\r\n";

print "Success!" . "\n";