ios学习--RSA非对称加密（解决解密后会乱码的问题）

在iOS中使用RSA加密解密，需要用到.der和.p12后缀格式的文件，其中.der格式的文件存放的是公钥（Public key）用于加密，.p12格式的文件存放的是私钥（Private key）用于解密. 首先需要先生成这些文件，然后再将文件导入工程使用，不多说，开始做！

一、使用openssl生成所需秘钥文件

生成环境是在mac系统下，使用openssl进行生成，首先打开终端，按下面这些步骤依次来做：

1. 生成模长为1024bit的私钥文件`private_key.pem`

openssl genrsa -outprivate_key.pem1024

2. 生成证书请求文件`rsaCertReq.csr`

openssl req -new -key private_key.pem -out rsaCerReq.csr

注意：这一步会提示输入国家、省份、mail等信息，可以根据实际情况填写，或者全部不用填写，直接全部敲回车.

3. 生成证书`rsaCert.crt`，并设置有效时间为1年

openssl x509 -req -days 3650 -in rsaCerReq.csr -signkey private_key.pem -out rsaCert.crt

4. 生成供iOS使用的公钥文件`public_key.der`

openssl x509 -outform der -in rsaCert.crt -out public_key.der

5. 生成供iOS使用的私钥文件`private_key.p12`

openssl pkcs12 -export -out private_key.p12 -inkey private_key.pem -in rsaCert.crt

注意：这一步会提示给私钥文件设置密码，直接输入想要设置密码即可，然后敲回车，然后再验证刚才设置的密码，再次输入密码，然后敲回车，完毕！
在解密时，private_key.p12文件需要和这里设置的密码配合使用，因此需要牢记此密码.

6. 生成供Java使用的公钥`rsa_public_key.pem`

openssl rsa -in private_key.pem -out rsa_public_key.pem -pubout

7. 生成供Java使用的私钥`pkcs8_private_key.pem`

openssl pkcs8 -topk8 -in private_key.pem -out pkcs8_private_key.pem -nocrypt

全部执行成功后，会生成如下文件，其中public_key.der和private_key.p12就是iOS需要用到的文件，如下图：

生成的文件

二、将文件导入工程使用

1.新建工程, 并导入`Security.framework`框架, 如下图:

新建工程并添加框架

2.导入秘钥文件

导入.der和.p12格式的秘钥文件, 如下图:

导入秘钥文件

3.新建用于加密、解密的类`RSAEncryptor`, 并实现相关方法

新建RSAEncryptor类, 如下图:

新建用于加密解密的类

下面开始上代码, 可以直接复制过去用:
RSAEncryptor.h代码如下:

<code class="objectivec"><span style="font-size: 18px;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title"><Foundation/Foundation.h></span></span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@interface</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">RSAEncryptor</span> : <span class="hljs-title" style="color: rgb(102, 0, 102);">NSObject</span></span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/**
 *  加密方法
 *
 *  @param str   需要加密的字符串
 *  @param path  '.der'格式的公钥文件路径
 */</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)encryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str publicKeyWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)path;

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/**
 *  解密方法
 *
 *  @param str       需要解密的字符串
 *  @param path      '.p12'格式的私钥文件路径
 *  @param password  私钥文件密码
 */</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)decryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str privateKeyWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)path password:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)password;

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/**
 *  加密方法
 *
 *  @param str    需要加密的字符串
 *  @param pubKey 公钥字符串
 */</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)encryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str publicKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)pubKey;

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/**
 *  解密方法
 *
 *  @param str     需要解密的字符串
 *  @param privKey 私钥字符串
 */</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)decryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str privateKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)privKey;

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span></span></code>

RSAEncryptor.m代码如下:

<code class="objectivec"><span style="font-size: 18px;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title">"RSAEncryptor.h"</span></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title"><Security/Security.h></span></span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@implementation</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">RSAEncryptor</span></span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">static</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *base64_encode_data(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data){
    data = [data base64EncodedDataWithOptions:<span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *ret = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> alloc] initWithData:data encoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">static</span> <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *base64_decode(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *str){
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> alloc] initWithBase64EncodedString:str options:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSDataBase64DecodingIgnoreUnknownCharacters</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> data;
}

<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#pragma mark - 使用'.der'公钥文件加密</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//加密</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)encryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str publicKeyWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)path{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!str || !path)  <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> encryptString:str publicKeyRef:[<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> getPublicKeyRefWithContentsOfFile:path]];
}

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//获取公钥</span>
+ (SecKeyRef)getPublicKeyRefWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)filePath{
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *certData = [<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> dataWithContentsOfFile:filePath];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!certData) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    SecCertificateRef cert = SecCertificateCreateWithData(<span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>, (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDataRef</span>)certData);
    SecKeyRef key = <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>;
    SecTrustRef trust = <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>;
    SecPolicyRef policy = <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (cert != <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>) {
        policy = SecPolicyCreateBasicX509();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (policy) {
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (SecTrustCreateWithCertificates((<span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFTypeRef</span>)cert, policy, &trust) == noErr) {
                SecTrustResultType result;
                <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (SecTrustEvaluate(trust, &result) == noErr) {
                    key = SecTrustCopyPublicKey(trust);
                }
            }
        }
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (policy) <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(policy);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (trust) <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(trust);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (cert) <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(cert);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> key;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)encryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str publicKeyRef:(SecKeyRef)publicKeyRef{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(![str dataUsingEncoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>]){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!publicKeyRef){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> encryptData:[str dataUsingEncoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>] withKeyRef:publicKeyRef];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *ret = base64_encode_data(data);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#pragma mark - 使用'.12'私钥文件解密</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//解密</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)decryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str privateKeyWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)path password:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)password{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!str || !path) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!password) password = <span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> decryptString:str privateKeyRef:[<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> getPrivateKeyRefWithContentsOfFile:path password:password]];
}

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//获取私钥</span>
+ (SecKeyRef)getPrivateKeyRefWithContentsOfFile:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)filePath password:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span>*)password{

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *p12Data = [<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> dataWithContentsOfFile:filePath];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!p12Data) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    SecKeyRef privateKeyRef = <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>;
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> * options = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> alloc] init];
    [options setObject: password forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecImportExportPassphrase];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFArrayRef</span> items = <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFArrayCreate</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>, <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>);
    OSStatus securityError = SecPKCS12Import((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDataRef</span>) p12Data, (__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)options, &items);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (securityError == noErr && <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFArrayGetCount</span>(items) > <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>) {
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span> identityDict = <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFArrayGetValueAtIndex</span>(items, <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>);
        SecIdentityRef identityApp = (SecIdentityRef)<span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryGetValue</span>(identityDict, kSecImportItemIdentity);
        securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (securityError != noErr) {
            privateKeyRef = <span class="hljs-literal" style="color: rgb(0, 102, 102);">NULL</span>;
        }
    }
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(items);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> privateKeyRef;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)decryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str privateKeyRef:(SecKeyRef)privKeyRef{
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> alloc] initWithBase64EncodedString:str options:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSDataBase64DecodingIgnoreUnknownCharacters</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!privKeyRef) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> decryptData:data withKeyRef:privKeyRef];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *ret = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> alloc] initWithData:data encoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#pragma mark - 使用公钥字符串加密</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/* START: Encryption with RSA public key */</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//使用公钥字符串加密</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)encryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str publicKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)pubKey{
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> encryptData:[str dataUsingEncoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>] publicKey:pubKey];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *ret = base64_encode_data(data);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)encryptData:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)data publicKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)pubKey{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!data || !pubKey){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    SecKeyRef keyRef = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> addPublicKey:pubKey];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!keyRef){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> encryptData:data withKeyRef:keyRef];
}

+ (SecKeyRef)addPublicKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)key{
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> spos = [key rangeOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"-----BEGIN PUBLIC KEY-----"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> epos = [key rangeOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"-----END PUBLIC KEY-----"</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> != <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNotFound</span> && epos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> != <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNotFound</span>){
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUInteger</span> s = spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> + spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.length</span>;
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUInteger</span> e = epos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span>;
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> range = <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMakeRange</span>(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\r"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\n"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\t"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@" "</span>  withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// This will be base64 encoded, decode it.</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = base64_decode(key);
    data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> stripPublicKeyHeader:data];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!data){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//a tag to read/write keychain storage</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *tag = <span class="hljs-string" style="color: rgb(0, 136, 0);">@"RSAUtil_PubKey"</span>;
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *d_tag = [<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> dataWithBytes:[tag UTF8String] length:[tag length]];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Delete any old lingering key with the same tag</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> *publicKey = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> alloc] init];
    [publicKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecClassKey forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecClass];
    [publicKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyTypeRSA forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrKeyType];
    [publicKey setObject:d_tag forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrApplicationTag];
    SecItemDelete((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)publicKey);

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Add persistent version of the key to system keychain</span>
    [publicKey setObject:data forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecValueData];
    [publicKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyClassPublic forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)
     kSecAttrKeyClass];
    [publicKey setObject:[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNumber</span> numberWithBool:<span class="hljs-literal" style="color: rgb(0, 102, 102);">YES</span>] forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)
     kSecReturnPersistentRef];

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFTypeRef</span> persistKey = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    OSStatus status = SecItemAdd((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)publicKey, &persistKey);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (persistKey != <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>){
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(persistKey);
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> ((status != noErr) && (status != errSecDuplicateItem)) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }

    [publicKey removeObjectForKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecValueData];
    [publicKey removeObjectForKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecReturnPersistentRef];
    [publicKey setObject:[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNumber</span> numberWithBool:<span class="hljs-literal" style="color: rgb(0, 102, 102);">YES</span>] forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecReturnRef];
    [publicKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyTypeRSA forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrKeyType];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Now fetch the SecKeyRef version of the key</span>
    SecKeyRef keyRef = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    status = SecItemCopyMatching((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)publicKey, (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFTypeRef</span> *)&keyRef);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(status != noErr){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> keyRef;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)stripPublicKeyHeader:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)d_key{
    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Skip ASN.1 public key header</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (d_key == <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">long</span> len = [d_key length];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!len) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> *c_key = (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> *)[d_key bytes];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span>  idx     = <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (c_key[idx++] != <span class="hljs-number" style="color: rgb(0, 102, 102);">0x30</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (c_key[idx] > <span class="hljs-number" style="color: rgb(0, 102, 102);">0x80</span>) idx += c_key[idx] - <span class="hljs-number" style="color: rgb(0, 102, 102);">0x80</span> + <span class="hljs-number" style="color: rgb(0, 102, 102);">1</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span> idx++;

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// PKCS #1 rsaEncryption szOID_RSA_RSA</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> seqiod[] =
    { <span class="hljs-number" style="color: rgb(0, 102, 102);">0x30</span>,   <span class="hljs-number" style="color: rgb(0, 102, 102);">0x0d</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x06</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x09</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x2a</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x86</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x48</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x86</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0xf7</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x0d</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x01</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x01</span>,
        <span class="hljs-number" style="color: rgb(0, 102, 102);">0x01</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x05</span>, <span class="hljs-number" style="color: rgb(0, 102, 102);">0x00</span> };
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (memcmp(&c_key[idx], seqiod, <span class="hljs-number" style="color: rgb(0, 102, 102);">15</span>)) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    idx += <span class="hljs-number" style="color: rgb(0, 102, 102);">15</span>;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (c_key[idx++] != <span class="hljs-number" style="color: rgb(0, 102, 102);">0x03</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (c_key[idx] > <span class="hljs-number" style="color: rgb(0, 102, 102);">0x80</span>) idx += c_key[idx] - <span class="hljs-number" style="color: rgb(0, 102, 102);">0x80</span> + <span class="hljs-number" style="color: rgb(0, 102, 102);">1</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span> idx++;

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (c_key[idx++] != <span class="hljs-string" style="color: rgb(0, 136, 0);">'\0'</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Now make a new NSData from this buffer</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ([<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> dataWithBytes:&c_key[idx] length:len - idx]);
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)encryptData:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)data withKeyRef:(SecKeyRef) keyRef{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">const</span> uint8_t *srcbuf = (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">const</span> uint8_t *)[data bytes];
    size_t srclen = (size_t)data<span class="hljs-variable" style="color: rgb(102, 0, 102);">.length</span>;

    size_t block_size = SecKeyGetBlockSize(keyRef) * <span class="hljs-keyword" style="color: rgb(0, 0, 136);">sizeof</span>(uint8_t);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">void</span> *outbuf = malloc(block_size);
    size_t src_block_size = block_size - <span class="hljs-number" style="color: rgb(0, 102, 102);">11</span>;

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableData</span> *ret = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableData</span> alloc] init];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">for</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> idx=<span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>; idx<srclen; idx+=src_block_size){
        <span class="hljs-comment" style="color: rgb(136, 0, 0);">//NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);</span>
        size_t data_len = srclen - idx;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(data_len > src_block_size){
            data_len = src_block_size;
        }

        size_t outlen = block_size;
        OSStatus status = noErr;
        status = SecKeyEncrypt(keyRef,
                               kSecPaddingPKCS1,
                               srcbuf + idx,
                               data_len,
                               outbuf,
                               &outlen
                               );
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (status != <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>) {
            <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"SecKeyEncrypt fail. Error Code: %d"</span>, status);
            ret = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">break</span>;
        }<span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span>{
            [ret appendBytes:outbuf length:outlen];
        }
    }

    free(outbuf);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(keyRef);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/* END: Encryption with RSA public key */</span>

<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#pragma mark - 使用私钥字符串解密</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/* START: Decryption with RSA private key */</span>

<span class="hljs-comment" style="color: rgb(136, 0, 0);">//使用私钥字符串解密</span>
+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)decryptString:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)str privateKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)privKey{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!str) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> alloc] initWithBase64EncodedString:str options:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSDataBase64DecodingIgnoreUnknownCharacters</span>];
    data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> decryptData:data privateKey:privKey];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *ret = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> alloc] initWithData:data encoding:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUTF8StringEncoding</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)decryptData:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)data privateKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)privKey{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!data || !privKey){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    SecKeyRef keyRef = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> addPrivateKey:privKey];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!keyRef){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> decryptData:data withKeyRef:keyRef];
}

+ (SecKeyRef)addPrivateKey:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *)key{
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> spos = [key rangeOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"-----BEGIN RSA PRIVATE KEY-----"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> epos = [key rangeOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"-----END RSA PRIVATE KEY-----"</span>];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> != <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNotFound</span> && epos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> != <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNotFound</span>){
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUInteger</span> s = spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span> + spos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.length</span>;
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSUInteger</span> e = epos<span class="hljs-variable" style="color: rgb(102, 0, 102);">.location</span>;
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSRange</span> range = <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMakeRange</span>(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\r"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\n"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"\t"</span> withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];
    key = [key stringByReplacingOccurrencesOfString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@" "</span>  withString:<span class="hljs-string" style="color: rgb(0, 136, 0);">@""</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// This will be base64 encoded, decode it.</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *data = base64_decode(key);
    data = [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">self</span> stripPrivateKeyHeader:data];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(!data){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//a tag to read/write keychain storage</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *tag = <span class="hljs-string" style="color: rgb(0, 136, 0);">@"RSAUtil_PrivKey"</span>;
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *d_tag = [<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> dataWithBytes:[tag UTF8String] length:[tag length]];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Delete any old lingering key with the same tag</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> *privateKey = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableDictionary</span> alloc] init];
    [privateKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecClassKey forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecClass];
    [privateKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyTypeRSA forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrKeyType];
    [privateKey setObject:d_tag forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrApplicationTag];
    SecItemDelete((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)privateKey);

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Add persistent version of the key to system keychain</span>
    [privateKey setObject:data forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecValueData];
    [privateKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyClassPrivate forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)
     kSecAttrKeyClass];
    [privateKey setObject:[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNumber</span> numberWithBool:<span class="hljs-literal" style="color: rgb(0, 102, 102);">YES</span>] forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)
     kSecReturnPersistentRef];

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFTypeRef</span> persistKey = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    OSStatus status = SecItemAdd((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)privateKey, &persistKey);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (persistKey != <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>){
        <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(persistKey);
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> ((status != noErr) && (status != errSecDuplicateItem)) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }

    [privateKey removeObjectForKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecValueData];
    [privateKey removeObjectForKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecReturnPersistentRef];
    [privateKey setObject:[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSNumber</span> numberWithBool:<span class="hljs-literal" style="color: rgb(0, 102, 102);">YES</span>] forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecReturnRef];
    [privateKey setObject:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>) kSecAttrKeyTypeRSA forKey:(__bridge <span class="hljs-keyword" style="color: rgb(0, 0, 136);">id</span>)kSecAttrKeyType];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Now fetch the SecKeyRef version of the key</span>
    SecKeyRef keyRef = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    status = SecItemCopyMatching((__bridge <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFDictionaryRef</span>)privateKey, (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFTypeRef</span> *)&keyRef);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(status != noErr){
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
    }
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> keyRef;
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)stripPrivateKeyHeader:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)d_key{
    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Skip ASN.1 private key header</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (d_key == <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">long</span> len = [d_key length];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!len) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span>(<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>);

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> *c_key = (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> *)[d_key bytes];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span>  idx     = <span class="hljs-number" style="color: rgb(0, 102, 102);">22</span>; <span class="hljs-comment" style="color: rgb(136, 0, 0);">//magic byte at offset 22</span>

    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (<span class="hljs-number" style="color: rgb(0, 102, 102);">0x04</span> != c_key[idx++]) <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//calculate length of the key</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> c_len = c_key[idx++];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> det = c_len & <span class="hljs-number" style="color: rgb(0, 102, 102);">0x80</span>;
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (!det) {
        c_len = c_len & <span class="hljs-number" style="color: rgb(0, 102, 102);">0x7f</span>;
    } <span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span> {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> byteCount = c_len & <span class="hljs-number" style="color: rgb(0, 102, 102);">0x7f</span>;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (byteCount + idx > len) {
            <span class="hljs-comment" style="color: rgb(136, 0, 0);">//rsa length field longer than buffer</span>
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
        }
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> accum = <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">unsigned</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136);">char</span> *ptr = &c_key[idx];
        idx += byteCount;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">while</span> (byteCount) {
            accum = (accum << <span class="hljs-number" style="color: rgb(0, 102, 102);">8</span>) + *ptr;
            ptr++;
            byteCount--;
        }
        c_len = accum;
    }

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Now make a new NSData from this buffer</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> [d_key subdataWithRange:<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMakeRange</span>(idx, c_len)];
}

+ (<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)decryptData:(<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSData</span> *)data withKeyRef:(SecKeyRef) keyRef{
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">const</span> uint8_t *srcbuf = (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">const</span> uint8_t *)[data bytes];
    size_t srclen = (size_t)data<span class="hljs-variable" style="color: rgb(102, 0, 102);">.length</span>;

    size_t block_size = SecKeyGetBlockSize(keyRef) * <span class="hljs-keyword" style="color: rgb(0, 0, 136);">sizeof</span>(uint8_t);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">UInt8</span> *outbuf = malloc(block_size);
    size_t src_block_size = block_size;

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableData</span> *ret = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSMutableData</span> alloc] init];
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">for</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> idx=<span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>; idx<srclen; idx+=src_block_size){
        <span class="hljs-comment" style="color: rgb(136, 0, 0);">//NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);</span>
        size_t data_len = srclen - idx;
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span>(data_len > src_block_size){
            data_len = src_block_size;
        }

        size_t outlen = block_size;
        OSStatus status = noErr;
        status = SecKeyDecrypt(keyRef,
                               kSecPaddingNone,
                               srcbuf + idx,
                               data_len,
                               outbuf,
                               &outlen
                               );
        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> (status != <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>) {
            <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"SecKeyEncrypt fail. Error Code: %d"</span>, status);
            ret = <span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>;
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">break</span>;
        }<span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span>{
            <span class="hljs-comment" style="color: rgb(136, 0, 0);">//the actual decrypted data is in the middle, locate it!</span>
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> idxFirstZero = -<span class="hljs-number" style="color: rgb(0, 102, 102);">1</span>;
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> idxNextZero = (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span>)outlen;
            <span class="hljs-keyword" style="color: rgb(0, 0, 136);">for</span> ( <span class="hljs-keyword" style="color: rgb(0, 0, 136);">int</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span>; i < outlen; i++ ) {
                <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> ( outbuf[i] == <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span> ) {
                    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">if</span> ( idxFirstZero < <span class="hljs-number" style="color: rgb(0, 102, 102);">0</span> ) {
                        idxFirstZero = i;
                    } <span class="hljs-keyword" style="color: rgb(0, 0, 136);">else</span> {
                        idxNextZero = i;
                        <span class="hljs-keyword" style="color: rgb(0, 0, 136);">break</span>;
                    }
                }
            }

            [ret appendBytes:&outbuf[idxFirstZero+<span class="hljs-number" style="color: rgb(0, 102, 102);">1</span>] length:idxNextZero-idxFirstZero-<span class="hljs-number" style="color: rgb(0, 102, 102);">1</span>];
        }
    }

    free(outbuf);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">CFRelease</span>(keyRef);
    <span class="hljs-keyword" style="color: rgb(0, 0, 136);">return</span> ret;
}

<span class="hljs-comment" style="color: rgb(136, 0, 0);">/* END: Decryption with RSA private key */</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span></span></code>

4. 测试加密、解密

首先先测试使用.der和.p12秘钥文件进行加密、解密, 在ViewController.m中进行测试, 代码如下:

<code class="objectivec"><span style="font-size: 18px;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title">"ViewController.h"</span></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title">"RSAEncryptor.h"</span></span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@interface</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">ViewController</span> ()</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@implementation</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">ViewController</span></span>

- (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">void</span>)viewDidLoad {
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">super</span> viewDidLoad];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//原始数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *originalString = <span class="hljs-string" style="color: rgb(0, 136, 0);">@"这是一段将要使用'.der'文件加密的字符串!"</span>;

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//使用.der和.p12中的公钥私钥加密解密</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *public_key_path = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSBundle</span> mainBundle] pathForResource:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"public_key.der"</span> ofType:<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *private_key_path = [[<span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSBundle</span> mainBundle] pathForResource:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"private_key.p12"</span> ofType:<span class="hljs-literal" style="color: rgb(0, 102, 102);">nil</span>];

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *encryptStr = [RSAEncryptor encryptString:originalString publicKeyWithContentsOfFile:public_key_path];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"加密前:%@"</span>, originalString);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"加密后:%@"</span>, encryptStr);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"解密后:%@"</span>, [RSAEncryptor decryptString:encryptStr privateKeyWithContentsOfFile:private_key_path password:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"123456"</span>]);

}

- (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">void</span>)didReceiveMemoryWarning {
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">super</span> didReceiveMemoryWarning];
    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Dispose of any resources that can be recreated.</span>
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span></span></code>

运行后, 输出信息如下:

输出结果

可以看到已经可以成功加密、解密了.

下面接着测试使用秘钥字符串进行加密、解密, 那么秘钥字符串从哪里来? 可以来这里:http://web.chacuo.net/netrsakeypair, 这是一个在线生成RSA秘钥的网站, 生成公钥和秘钥后, 复制出来用于测试. 然后在ViewController.m中使用RSAEntryptor.h头文件中对应的加密方法进行加密, ViewController.m中代码如下:

<code class="objectivec"><span style="font-size: 18px;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title">"ViewController.h"</span></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68);">#import <span class="hljs-title">"RSAEncryptor.h"</span></span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@interface</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">ViewController</span> ()</span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span>

<span class="hljs-class"><span class="hljs-keyword" style="color: rgb(0, 0, 136);">@implementation</span> <span class="hljs-title" style="color: rgb(102, 0, 102);">ViewController</span></span>

- (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">void</span>)viewDidLoad {
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">super</span> viewDidLoad];

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//原始数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *originalString = <span class="hljs-string" style="color: rgb(0, 136, 0);">@"这是一段将要使用'秘钥字符串'进行加密的字符串!"</span>;

    <span class="hljs-comment" style="color: rgb(136, 0, 0);">//使用字符串格式的公钥私钥加密解密</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSString</span> *encryptStr = [RSAEncryptor encryptString:originalString publicKey:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDTbZ6cNH9PgdF60aQKveLz3FTalyzHQwbp601y77SzmGHX3F5NoVUZbdK7UMdoCLK4FBziTewYD9DWvAErXZo9BFuI96bAop8wfl1VkZyyHTcznxNJFGSQd/B70/ExMgMBpEwkAAdyUqIjIdVGh1FQK/4acwS39YXwbS+IlHsPSQIDAQAB"</span>];

    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"加密前:%@"</span>, originalString);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"加密后:%@"</span>, encryptStr);
    <span class="hljs-built_in" style="color: rgb(102, 0, 102);">NSLog</span>(<span class="hljs-string" style="color: rgb(0, 136, 0);">@"解密后:%@"</span>, [RSAEncryptor decryptString:encryptStr privateKey:<span class="hljs-string" style="color: rgb(0, 136, 0);">@"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"</span>]);

}

- (<span class="hljs-keyword" style="color: rgb(0, 0, 136);">void</span>)didReceiveMemoryWarning {
    [<span class="hljs-keyword" style="color: rgb(0, 0, 136);">super</span> didReceiveMemoryWarning];
    <span class="hljs-comment" style="color: rgb(136, 0, 0);">// Dispose of any resources that can be recreated.</span>
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136);">@end</span></span></code>

运行后, 输出信息如下:

输出结果

可以看到,也成功加密、解密了.

至此, RSA加密演示完毕!

文／jianshu_wl（简书作者）
原文链接：http://www.jianshu.com/p/74a796ec5038

一、使用openssl生成所需秘钥文件

1. 生成模长为1024bit的私钥文件private_key.pem

2. 生成证书请求文件rsaCertReq.csr

3. 生成证书rsaCert.crt，并设置有效时间为1年

4. 生成供iOS使用的公钥文件public_key.der

5. 生成供iOS使用的私钥文件private_key.p12

6. 生成供Java使用的公钥rsa_public_key.pem

7. 生成供Java使用的私钥pkcs8_private_key.pem