RSA decryption using private key

Question

I have a private key and encrypted string. Actually string has been encrypted using .NET modules. Now I need to decrypted the string . I tried in php but it throws me following error

 openssl_private_decrypt(): key parameter is not a valid private key  

I tried in perl but there it takes its own private key, But it need to use my own private key, which has been generated in our server.

Please suggest me on this issue to overcome. PHP ,Ruby , Perl Solution would be more helpful.

$crypttext="gKL/n5hkBg4jyjrLRqjQbf9gAS3xnbp1xmCmamPO33fW21JAJtlVQHYR6O1dOw3tfobMe/0uXm/kgivae9zHNey4Wt3UGzPwosUrx7V8zhC97AXya2tuENO1Fmc4Z8l9+UalwtUZxMGtl3Ua9DYuvxLP/TuavgRNpmG6eemGPag=";
$fp=fopen("private.pem","r");
$priv_key=fread($fp,8192);
fclose($fp);
openssl_private_decrypt(base64_decode($crypttext ),$newsource,false ) ;
echo "String decrypt : $newsource"**;

Private Key

<BitStrength>1024</BitStrength><RSAKeyValue><Modulus>t2G2WWIal1EinPn54ZPc3S1UgGTDxr6RFc+XEMR723VSg9toU8lSfTD7C26bUcbDxBwP1/1MbdQcx/dKX+7UlB5z79vrwfT89rUZGWeH7VZvuAawtHURgucyGMhqAZ9NxDEAl5Uo3nsNL9j1JlSBfeZf8pU5sf70KezqJTRsfrE=</Modulus><Exponent>AQAB</Exponent><P>82dZbOjQCJ7NV6EuVJXqPlh4FB65LBL1w9696sKFZuIr8refGwTZOY05se6oHbT9mn8OFXVA6A/wmz7oWNPk9w==</P><Q>wN8uixNk73DIF2SHb0aunnW5XxAIq3KxeQKoUTBAzL7BqXmKjk6XDnfxDbybmcT51wGhiO20lGg51zuxnsPXlw==</Q><DP>Kv4+VXZqCJvEOY5G2LoCPjDyRNuIabiPoKFfenARkDKzAJReji81D21am4tENrsZcIiwvCmR5WurXECoWchT0Q==</DP><DQ>qGRzW4O0VYVvfVUNFi9tF/aKwR/boe0CXDfgwvnRKbHGnfP67+JX6o73zFmGtQuQYpMO+OEpD4WsMmnw2z/7ww==</DQ><InverseQ>czq4+xiiVxb63ZtKwkxyJoDLFH0f18YlfFQTrEoAx7UE9HdjOjsJFpZ54g0yK3/S/yVgIXPwMcw6LU1QvqazPg==</InverseQ><D>Ktp/tWWSlzfToeFcvpVCMMGOFK73fTM9Tl6Di9yOoRtKnBuixqmuSCkxEVvYmgSb7PEt1qiPur6ttyEX1VFHhaugTr3aVhUpF+k7ULaHrCb8UymXXW3pp/yl/QOMPWuNKVv/GU3aQ3VTc3WUaYuOnaIkJk7uoYDQn0QqWtxtT60=</D></RSAKeyValue>

Answer 1

phpseclib, a pure PHP RSA implementation, supports XML private keys in this format. Usage example:

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

$rsa = new Crypt_RSA();
$rsa->loadKey('...'); // private key

echo $rsa->decrypt($ciphertext);
?>