用基于openssl产生的密钥实现PHP和.NET端的RSA加解密互通

用openssl产生密钥对的方法：

下载openssl进入其中的bin目录，运行openssl.exe,并分别执行以下命令：

genrsa -out rsa_private_key.pem 1024
pkcs8 -topk8 -inform PEM -in rsa_private_key.pem -outform PEM -nocrypt -out private_key.pem
rsa -in rsa_private_key.pem -pubout -out rsa_public_key.pem

这将会在bin文件夹下生成两个pem文件rsa_private_key.pem和rsa_public_key.pem,这两个文件中分别存放了私钥和公钥。

PHP端单独实现RSA的方法：

进入php.ini,将extension=php_openssl.dll前面的分号(注释)去掉,重启wamp(使用的这个),就可以在PHP中使用openssl拓展函数了。

完整PHP测试代码如下

<?php
header("Content-Type: text/html; charset=utf-8");
$rsaKey = new RSAKey();
$privateKey = $rsaKey->getPrivateKey();
$publicKey = $rsaKey->getPublicKey();

$pi_key =  openssl_pkey_get_private("这里填用openssl生成的私钥字符串");
$pu_key = openssl_pkey_get_public("这里填用openssl生成的公钥字符串");

$data = "一段明文";
$encrypted = "";
$decrypted = "";

echo "原始数据:".$data."<BR>";

/**
私钥加密,公钥解密
*/
echo "私钥加密:<br>";
openssl_private_encrypt($data,$encrypted,$pi_key);//私钥加密
$encrypted = base64_encode($encrypted);//将机密后的字符串用base64转义一下，方便个别特殊字符的传输
echo $encrypted."<br>";

echo "公钥解密:<br>";
openssl_public_decrypt(base64_decode($encrypted),$decrypted,$pu_key);//公钥解密
echo $decrypted."<br>";


/**
公钥加密，私钥解密
*/
echo "公钥加密:<br>";
openssl_public_encrypt($data,$encrypted,$pu_key);//公钥加密
$encrypted = base64_encode($encrypted);

echo "私钥解密:<br>";
openssl_private_decrypt(base64_decode($encrypted),$decrypted,$pi_key);//私钥解密
echo $decrypted."<br>";
?>

上面的代码是可以成功的,但是在实际中会遇到这样一种情况

公司A有一个软件外包给公司B做了,那边用的是.net,公司这边运行的是PHP。

现在A生成了私钥和公钥,并将公钥提供给B，请问B用直接用.net中的rsa加密函数出来的密文，A是不能用php直接解出来的

这是由于.net中的RSA加解密是根据xml来实现的，也就是说参数的格式不同,要实现两种语言之间的互通，需要先将A提供给B的公钥进行转化下,转成.net可用的RSAParameter

以下是参考网上的http://www.cnblogs.com/thinhunan/archive/2009/09/10/ConvertPem2048ToRSAParemeters.html，感谢该作者

using System;
using System.Text;
using System.Security.Cryptography;
using System.Web;
using System.IO;

namespace Thinhunan.Cnblogs.Com.RSAUtility
{
    /// <summary>
    /// Author http://thinhunan.cnblogs.com
    /// </summary>
    public class PemConverter
    {
        /// <summary>
        /// 将pem格式公钥(1024 or 2048)转换为RSAParameters
        /// </summary>
        /// <param name="pemFileConent">pem公钥内容</param>
        /// <returns>转换得到的RSAParamenters</returns>
        public static RSAParameters ConvertFromPemPublicKey(string pemFileConent)
        {
            if (string.IsNullOrEmpty(pemFileConent))
            {
                throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
            }
            pemFileConent = pemFileConent.Replace("-----BEGIN PUBLIC KEY-----", "").Replace("-----END PUBLIC KEY-----", "").Replace("
", "").Replace("
", "");
            byte[] keyData = Convert.FromBase64String(pemFileConent);
            bool keySize1024 = (keyData.Length == 162);
            bool keySize2048 = (keyData.Length == 294);
            if (!( keySize1024 || keySize2048 ))
            {
                throw new ArgumentException("pem file content is incorrect, Only support the key size is 1024 or 2048");
            }
            byte[] pemModulus = (keySize1024? new byte[128] : new byte[256]);
            byte[] pemPublicExponent = new byte[3];
            Array.Copy(keyData, (keySize1024? 29:33), pemModulus, 0,(keySize1024?  128:256));
            Array.Copy(keyData, (keySize1024? 159:291), pemPublicExponent, 0, 3);
            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            return para;
        }

        /// <summary>
        /// 将pem格式私钥(1024 or 2048)转换为RSAParameters
        /// </summary>
        /// <param name="pemFileConent">pem私钥内容</param>
        /// <returns>转换得到的RSAParamenters</returns>
        public static RSAParameters ConvertFromPemPrivateKey(string pemFileConent)
        {
            if (string.IsNullOrEmpty(pemFileConent))
            {
                throw new ArgumentNullException("pemFileConent", "This arg cann't be empty.");
            }
            pemFileConent = pemFileConent.Replace("-----BEGIN RSA PRIVATE KEY-----", "").Replace("-----END RSA PRIVATE KEY-----", "").Replace("
", "").Replace("
","");
            byte[] keyData = Convert.FromBase64String(pemFileConent);

            bool keySize1024 = (keyData.Length == 609 || keyData.Length == 610);
            bool keySize2048 = (keyData.Length == 1190 || keyData.Length == 1192);
           
            if (!(keySize1024 || keySize2048))
            {
                throw new ArgumentException("pem file content is incorrect, Only support the key size is 1024 or 2048");
            }

            int index = ( keySize1024 ? 11 : 12);
            byte[] pemModulus =  ( keySize1024 ? new byte[128]:new byte[256]);
            Array.Copy(keyData, index, pemModulus, 0, pemModulus.Length);

            index += pemModulus.Length;
            index += 2;
            byte[] pemPublicExponent = new byte[3];
            Array.Copy(keyData, index, pemPublicExponent, 0, 3);

            index += 3;
            index += 4;
            if ((int)keyData[index] == 0)
            {
                index++;
            }
            byte[] pemPrivateExponent = (keySize1024 ? new byte[128] : new byte[256]);
            Array.Copy(keyData, index , pemPrivateExponent, 0, pemPrivateExponent.Length);

            index += pemPrivateExponent.Length;
            index += (keySize1024? ((int)keyData[index+1] == 64?2: 3):((int)keyData[index+2] == 128 ?3:4));
            byte[] pemPrime1 = (keySize1024 ? new byte[64] : new byte[128]);
            Array.Copy(keyData, index, pemPrime1, 0, pemPrime1.Length);

            index += pemPrime1.Length;
            index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
            byte[] pemPrime2 = (keySize1024 ? new byte[64] : new byte[128]);
            Array.Copy(keyData, index , pemPrime2, 0, pemPrime2.Length);

            index += pemPrime2.Length;
            index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
            byte[] pemExponent1 = (keySize1024 ? new byte[64] : new byte[128]);
            Array.Copy(keyData,index, pemExponent1, 0, pemExponent1.Length);

            index += pemExponent1.Length;
            index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
            byte[] pemExponent2 = (keySize1024 ? new byte[64] : new byte[128]);
            Array.Copy(keyData, index, pemExponent2, 0, pemExponent2.Length);

            index += pemExponent2.Length;
            index += (keySize1024 ? ((int)keyData[index + 1] == 64 ? 2 : 3) : ((int)keyData[index + 2] == 128 ? 3 : 4));
            byte[] pemCoefficient = (keySize1024 ? new byte[64] : new byte[128]);
            Array.Copy(keyData, index, pemCoefficient, 0, pemCoefficient.Length);

            RSAParameters para = new RSAParameters();
            para.Modulus = pemModulus;
            para.Exponent = pemPublicExponent;
            para.D = pemPrivateExponent;
            para.P = pemPrime1;
            para.Q = pemPrime2;
            para.DP = pemExponent1;
            para.DQ = pemExponent2;
            para.InverseQ = pemCoefficient;
            return para;
        }
        
    }
}

 用该方法生成的密文可以被PHP使用了