首先，关于RSA的加密介绍文章，就不多说了。直接看这个网页吧(作者写的计算机科普文章是极好的)

http://www.ruanyifeng.com/blog/2013/06/rsa_algorithm_part_one.html

我要实现的功能就是通过这对公钥和密钥，实现客户端软件对密码进行加密(采用公钥)，然后网站端(php)采用密钥进行解密验证。

开始吧。

php服务端利用内置函数生成公钥和密钥。记得这需要php服务器安装了openssl扩展。先生成cer文件和pfx文件。cer文件相当于公钥(可以发给客户端)，pfx是密钥(必须严格保存于服务器端不能泄露)。

$dn = array(

"countryName" => 'zh', //所在国家名称

"stateOrProvinceName" => 'GuangDong', //所在省份名称

"localityName" => 'ShenZhen', //所在城市名称

"organizationName" => 'baibai', //注册人姓名

"organizationalUnitName" => 'company', //组织名称

"commonName" => 'bbb', //公共名称

"emailAddress" => '123@.qq.com' //邮箱

);

$privkeypass = 'cf'; //私钥密码

$numberofdays = 3650; //有效时长

$cerpath = "./test.cer"; //生成证书路径

$pfxpath = "./test.pfx"; //密钥文件路径//生成证书

$privkey = openssl_pkey_new();

$csr = openssl_csr_new($dn, $privkey);

$sscert = openssl_csr_sign($csr, null, $privkey, $numberofdays);

openssl_x509_export_to_file($sscert, $cerpath); //导出证书到文件

//openssl_pkcs12_export_to_file($sscert, $pfxpath, $privkey, $privkeypass); //生成密钥文件

openssl_pkey_export_to_file($privkey, $pfxpath); //生成密钥文件

以下是是php端进行简单测试的代码：

/*

//私钥加密

$cer_key = file_get_contents($pfxpath); //获取密钥内容

openssl_pkcs12_read($cer_key, $certs, $privkeypass);

openssl_sign($data, $signMsg, $certs['pkey'],OPENSSL_ALGO_SHA1); //注册生成加密信息

$signMsg = base64_encode($signMsg); //base64转码加密信息

//echo $signMsg;

//公钥解密

$cer_key = file_get_contents($cerpath); //获取证书内容

$unsignMsg=base64_decode($signMsg);//base64解码加密信息

$cer = openssl_x509_read($cer_key); //读取公钥

$res = openssl_verify($data, $unsignMsg, $cer); //验证

echo $res; //输出验证结果，1：验证成功，0：验证失败

*/

$data = "123456";

$crypted = "";

$key = file_get_contents($cerpath);

//公钥加密

openssl_public_encrypt($data, $crypted, $key);

echo base64_encode($crypted)."
";

//echo $crypted."
";

//私钥解密

$decrypted = "";

$s = file_get_contents($pfxpath);

//echo "
$s
";

$key2 = openssl_pkey_get_private(file_get_contents($pfxpath));

if(openssl_private_decrypt($crypted, $decrypted, $key2)){

echo $decrypted;

}

else{

echo "failed";

}

客户端通过加载cer文件，将要加密的文本用公钥加密。以下是一个函数

//通过读取本地的cer文件，得到公钥，然后对文本内容加密，返回加密后的文本，最后传到服务器端，与密钥进行比对

public static String getRSAText(Context context,String strText){

try {

//读取证书文件

InputStream inStream = context.getResources().getAssets().open("test.cer");

//创建X509工厂类

CertificateFactory cf = CertificateFactory.getInstance("X.509");

//创建证书对象

X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);

inStream.close();

Cipher c1 = Cipher.getInstance("RSA/None/PKCS1Padding");

c1.init(Cipher.PUBLIC_KEY, cert);

byte[] cipherText = c1.doFinal(strText.getBytes());

//base64转换一下，方便传输

String res = Base64.encodeToString(cipherText,Base64.DEFAULT);

return res;

}

catch (InvalidKeyException e){

}

catch (IOException e){

}

catch (CertificateException e){

}

catch (NoSuchPaddingException e){

}

catch (IllegalBlockSizeException e){

}

catch (BadPaddingException e){

}

catch (NoSuchAlgorithmException e){

}

return "";

}

下边是php端用pfx文件(里边放有密钥)进行解密的代码。我改写成了一个函数。参数是pfx文件路径，pfx文件名，要解密的字符串

function getPassword( $path,$pfx_file_name,$str ){

$pfxpath = $path . "/public/$pfx_file_name"; //密钥文件路径

//$cerpath = "./test.cer"; //生成证书路径

//私钥解密

$decrypted = "";

$key2 = openssl_pkey_get_private(file_get_contents($pfxpath));

$res = openssl_private_decrypt(base64_decode($str), $decrypted, $key2);

if($res){

return $decrypted;

}

else{

return "";

}

}