MK_EncryOp.m

//
//  MK_EncryOp.m
//  加密
//
//  Created by MBP on 2017/11/20.
//  Copyright © 2017年 leqi. All rights reserved.
//

#import "MK_EncryOp.h"
#import <Security/Security.h>

@implementation MK_EncryOp
#pragma mark Base64 相关
+(NSString*)base64EncodeWithData:(NSData*)data{
    data = [data base64EncodedDataWithOptions:0];
    NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    return ret;
}

+(NSData*)base64DecodeWithData:(NSString*)str{
    NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
    return data;
}

#pragma mark - AES相关
+(NSData *)AESEncryptWithdData:(NSData *)content andKeySize:(CCOptions)kKeySize andKey:(NSString *)key andIV:(NSString*)iv{
    return [self AES:kCCEncrypt andKeySize:kKeySize andData:content andKey:key andIV:iv];
}

+(NSData *)AESDecryptWithdData:(NSData *)content andKeySize:(CCOptions)kKeySize andKey:(NSString *)key andIV:(NSString*)iv{
    return [self AES:kCCDecrypt andKeySize:kKeySize andData:content andKey:key andIV:iv];
}


+(NSData *)AES:(CCOperation)AESType andKeySize:(CCOptions)kKeySize andData:(NSData *)content andKey:(NSString *)key andIV:(NSString*)iv{

    NSData *contentData = content;
    NSUInteger dataLength = contentData.length;


    //设置加密秘钥,因C字符串结束符为'\0' 所以大小+1
    char keyPtr[kKeySize + 1];
    memset(keyPtr, 0, sizeof(keyPtr));
    //应确保大小小于等于16个字节.
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];

    NSLog(@"=%@=",[[NSString alloc] initWithCString:keyPtr encoding:NSUTF8StringEncoding]);

    //密文长度 = 明文长度+秘钥长度
    size_t encryptSize = dataLength + kCCBlockSizeAES128;
    void *encryptedBytes = malloc(encryptSize);
    //密文接受指针
    size_t actualOutSize = 0;
    //初始向量
    NSData *initVector = [iv dataUsingEncoding:NSUTF8StringEncoding];

    CCCryptorStatus cryptStatus = CCCrypt(AESType,                  //是加密还是解密
                                          kCCAlgorithmAES,          //加密/解密方式
                                          kCCOptionPKCS7Padding,    //PKCS7Padding
                                          keyPtr,                   //秘钥
                                          kKeySize,                 //秘钥大小
                                          initVector.bytes,         //初始向量
                                          contentData.bytes,        //明文/密文
                                          dataLength,               //明文/密文大小
                                          encryptedBytes,           //结果: 密文/明文缓冲区
                                          encryptSize,              //结果: 密文/明文大小
                                          &actualOutSize);          //结果指针

    if (cryptStatus == kCCSuccess) {
        // 成功
        return [NSData dataWithBytesNoCopy:encryptedBytes length:actualOutSize];
    }
    //释放
    free(encryptedBytes);
    return nil;
}



#pragma mark - 散列函数
+(NSString *)md5WithStr:(NSString*)string{
    const char *str = string.UTF8String;
    uint8_t buffer[CC_MD5_DIGEST_LENGTH];
    
    CC_MD5(str, (CC_LONG)strlen(str), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_MD5_DIGEST_LENGTH];
}

+(NSString *)sha1WithStr:(NSString*)string{
    const char *str = string.UTF8String;
    uint8_t buffer[CC_SHA1_DIGEST_LENGTH];
    
    CC_SHA1(str, (CC_LONG)strlen(str), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA1_DIGEST_LENGTH];
}

+(NSString *)sha256WithStr:(NSString*)string{
    const char *str = string.UTF8String;
    uint8_t buffer[CC_SHA256_DIGEST_LENGTH];
    
    CC_SHA256(str, (CC_LONG)strlen(str), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA256_DIGEST_LENGTH];
}

+(NSString *)sha512WithStr:(NSString*)string{
    const char *str = string.UTF8String;
    uint8_t buffer[CC_SHA512_DIGEST_LENGTH];
    
    CC_SHA512(str, (CC_LONG)strlen(str), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA512_DIGEST_LENGTH];
}

#pragma mark - HMAC 散列函数
+(NSString *)hmacMD5StringWithStr:(NSString*)string andWithKey:(NSString *)key{
    const char *keyData = key.UTF8String;
    const char *strData = string.UTF8String;
    uint8_t buffer[CC_MD5_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgMD5, keyData, strlen(keyData), strData, strlen(strData), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_MD5_DIGEST_LENGTH];
}

+(NSString *)hmacSHA1WithStr:(NSString*)string andWithKey:(NSString *)key{
    const char *keyData = key.UTF8String;
    const char *strData = string.UTF8String;
    uint8_t buffer[CC_SHA1_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgSHA1, keyData, strlen(keyData), strData, strlen(strData), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA1_DIGEST_LENGTH];
}

+(NSString *)hmacSHA256WithStr:(NSString*)string andWithKey:(NSString *)key{
    const char *keyData = key.UTF8String;
    const char *strData = string.UTF8String;
    uint8_t buffer[CC_SHA256_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgSHA256, keyData, strlen(keyData), strData, strlen(strData), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA256_DIGEST_LENGTH];
}

+(NSString *)hmacSHA512WithStr:(NSString*)string andWithKey:(NSString *)key{
    const char *keyData = key.UTF8String;
    const char *strData = string.UTF8String;
    uint8_t buffer[CC_SHA512_DIGEST_LENGTH];
    
    CCHmac(kCCHmacAlgSHA512, keyData, strlen(keyData), strData, strlen(strData), buffer);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA512_DIGEST_LENGTH];
}

#pragma mark - 文件散列函数

#define FileHashDefaultChunkSizeForReadingData 4096

+(NSString *)md5FileWithPath:(NSString*)path{
    NSFileHandle *fp = [NSFileHandle fileHandleForReadingAtPath:path];
    if (fp == nil) {
        return nil;
    }
    
    CC_MD5_CTX hashCtx;
    CC_MD5_Init(&hashCtx);
    
    while (YES) {
        @autoreleasepool {
            NSData *data = [fp readDataOfLength:FileHashDefaultChunkSizeForReadingData];
            
            CC_MD5_Update(&hashCtx, data.bytes, (CC_LONG)data.length);
            
            if (data.length == 0) {
                break;
            }
        }
    }
    [fp closeFile];
    
    uint8_t buffer[CC_MD5_DIGEST_LENGTH];
    CC_MD5_Final(buffer, &hashCtx);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_MD5_DIGEST_LENGTH];
}

+(NSString *)sha1WithPath:(NSString*)path{
    NSFileHandle *fp = [NSFileHandle fileHandleForReadingAtPath:path];
    if (fp == nil) {
        return nil;
    }
    
    CC_SHA1_CTX hashCtx;
    CC_SHA1_Init(&hashCtx);
    
    while (YES) {
        @autoreleasepool {
            NSData *data = [fp readDataOfLength:FileHashDefaultChunkSizeForReadingData];
            
            CC_SHA1_Update(&hashCtx, data.bytes, (CC_LONG)data.length);
            
            if (data.length == 0) {
                break;
            }
        }
    }
    [fp closeFile];
    
    uint8_t buffer[CC_SHA1_DIGEST_LENGTH];
    CC_SHA1_Final(buffer, &hashCtx);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA1_DIGEST_LENGTH];
}

+(NSString *)sha256WithPath:(NSString*)path{
    NSFileHandle *fp = [NSFileHandle fileHandleForReadingAtPath:path];
    if (fp == nil) {
        return nil;
    }
    
    CC_SHA256_CTX hashCtx;
    CC_SHA256_Init(&hashCtx);
    
    while (YES) {
        @autoreleasepool {
            NSData *data = [fp readDataOfLength:FileHashDefaultChunkSizeForReadingData];
            
            CC_SHA256_Update(&hashCtx, data.bytes, (CC_LONG)data.length);
            
            if (data.length == 0) {
                break;
            }
        }
    }
    [fp closeFile];
    
    uint8_t buffer[CC_SHA256_DIGEST_LENGTH];
    CC_SHA256_Final(buffer, &hashCtx);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA256_DIGEST_LENGTH];
}

+(NSString *)sha512WithPath:(NSString*)path{
    NSFileHandle *fp = [NSFileHandle fileHandleForReadingAtPath:path];
    if (fp == nil) {
        return nil;
    }
    
    CC_SHA512_CTX hashCtx;
    CC_SHA512_Init(&hashCtx);
    
    while (YES) {
        @autoreleasepool {
            NSData *data = [fp readDataOfLength:FileHashDefaultChunkSizeForReadingData];
            
            CC_SHA512_Update(&hashCtx, data.bytes, (CC_LONG)data.length);
            
            if (data.length == 0) {
                break;
            }
        }
    }
    [fp closeFile];
    
    uint8_t buffer[CC_SHA512_DIGEST_LENGTH];
    CC_SHA512_Final(buffer, &hashCtx);
    
    return [MK_EncryOp stringFromBytes:buffer length:CC_SHA512_DIGEST_LENGTH];
}

#pragma mark - 助手方法
/**
 *  返回二进制 Bytes 流的字符串表示形式
 *
 *  @param bytes  二进制 Bytes 数组
 *  @param length 数组长度
 *
 *  @return 字符串表示形式
 */
+(NSString *)stringFromBytes:(uint8_t *)bytes length:(int)length{
    NSMutableString *strM = [NSMutableString string];
    for (int i = 0; i < length; i++) {
        [strM appendFormat:@"%02x", bytes[i]];
    }
    
    return [strM copy];
}


#pragma mark - RSA加密解密相关
#pragma mark - 使用'.der'公钥文件加密

//加密
+ (NSString *)RSAencryptString:(NSString *)str publicKeyWithContentsOfFile:(NSString *)path{
    if (!str || !path)  return nil;
    return [self RSAencryptString:str publicKeyRef:[self getPublicKeyRefWithContentsOfFile:path]];
}

//获取公钥
+ (SecKeyRef)getPublicKeyRefWithContentsOfFile:(NSString *)filePath{
    NSData *certData = [NSData dataWithContentsOfFile:filePath];
    if (!certData) {
        return nil;
    }
    SecCertificateRef cert = SecCertificateCreateWithData(NULL, (CFDataRef)certData);
    SecKeyRef key = NULL;
    SecTrustRef trust = NULL;
    SecPolicyRef policy = NULL;
    if (cert != NULL) {
        policy = SecPolicyCreateBasicX509();
        if (policy) {
            if (SecTrustCreateWithCertificates((CFTypeRef)cert, policy, &trust) == noErr) {
                SecTrustResultType result;
                if (SecTrustEvaluate(trust, &result) == noErr) {
                    key = SecTrustCopyPublicKey(trust);
                }
            }
        }
    }
    if (policy) CFRelease(policy);
    if (trust) CFRelease(trust);
    if (cert) CFRelease(cert);
    return key;
}

+ (NSString *)RSAencryptString:(NSString *)str publicKeyRef:(SecKeyRef)publicKeyRef{
    if(![str dataUsingEncoding:NSUTF8StringEncoding]){
        return nil;
    }
    if(!publicKeyRef){
        return nil;
    }
    NSData *data = [self RSAencryptData:[str dataUsingEncoding:NSUTF8StringEncoding] withKeyRef:publicKeyRef];
    NSString *ret = [MK_EncryOp base64EncodeWithData:data];
    return ret;
}

#pragma mark - 使用'.p12'私钥文件解密

//解密
+ (NSString *)RSAdecryptString:(NSString *)str privateKeyWithContentsOfFile:(NSString *)path password:(NSString *)password{
    if (!str || !path) return nil;
    if (!password) password = @"";
    return [self RSAdecryptString:str privateKeyRef:[self getPrivateKeyRefWithContentsOfFile:path password:password]];
}

//获取私钥
+ (SecKeyRef)getPrivateKeyRefWithContentsOfFile:(NSString *)filePath password:(NSString*)password{

    NSData *p12Data = [NSData dataWithContentsOfFile:filePath];
    if (!p12Data) {
        return nil;
    }
    SecKeyRef privateKeyRef = NULL;
    NSMutableDictionary * options = [[NSMutableDictionary alloc] init];
    [options setObject: password forKey:(__bridge id)kSecImportExportPassphrase];
    CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
    OSStatus securityError = SecPKCS12Import((__bridge CFDataRef) p12Data, (__bridge CFDictionaryRef)options, &items);
    if (securityError == noErr && CFArrayGetCount(items) > 0) {
        CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
        SecIdentityRef identityApp = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
        securityError = SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);
        if (securityError != noErr) {
            privateKeyRef = NULL;
        }
    }
    CFRelease(items);

    return privateKeyRef;
}

+ (NSString *)RSAdecryptString:(NSString *)str privateKeyRef:(SecKeyRef)privKeyRef{
    NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
    if (!privKeyRef) {
        return nil;
    }
    data = [self RSAdecryptData:data withKeyRef:privKeyRef];
    NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    return ret;
}

#pragma mark - 使用公钥字符串加密

/* START: Encryption with RSA public key */

//使用公钥字符串加密
+ (NSString *)RSAencryptString:(NSString *)str publicKey:(NSString *)pubKey{
    NSData *data = [self RSAencryptData:[str dataUsingEncoding:NSUTF8StringEncoding] publicKey:pubKey];
    NSString *ret =[MK_EncryOp base64EncodeWithData:data];
    return ret;
}

+ (NSData *)RSAencryptData:(NSData *)data publicKey:(NSString *)pubKey{
    if(!data || !pubKey){
        return nil;
    }
    SecKeyRef keyRef = [self addPublicKey:pubKey];
    if(!keyRef){
        return nil;
    }
    return [self RSAencryptData:data withKeyRef:keyRef];
}

+ (SecKeyRef)addPublicKey:(NSString *)key{
    NSRange spos = [key rangeOfString:@"-----BEGIN PUBLIC KEY-----"];
    NSRange epos = [key rangeOfString:@"-----END PUBLIC KEY-----"];
    if(spos.location != NSNotFound && epos.location != NSNotFound){
        NSUInteger s = spos.location + spos.length;
        NSUInteger e = epos.location;
        NSRange range = NSMakeRange(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@" "  withString:@""];

    // This will be base64 encoded, decode it.
    NSData *data = [MK_EncryOp base64DecodeWithData:key];
    data = [self stripPublicKeyHeader:data];
    if(!data){
        return nil;
    }

    //a tag to read/write keychain storage
    NSString *tag = @"RSAUtil_PubKey";
    NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];

    // Delete any old lingering key with the same tag
    NSMutableDictionary *publicKey = [[NSMutableDictionary alloc] init];
    [publicKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [publicKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
    SecItemDelete((__bridge CFDictionaryRef)publicKey);

    // Add persistent version of the key to system keychain
    [publicKey setObject:data forKey:(__bridge id)kSecValueData];
    [publicKey setObject:(__bridge id) kSecAttrKeyClassPublic forKey:(__bridge id)
     kSecAttrKeyClass];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
     kSecReturnPersistentRef];

    CFTypeRef persistKey = nil;
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)publicKey, &persistKey);
    if (persistKey != nil){
        CFRelease(persistKey);
    }
    if ((status != noErr) && (status != errSecDuplicateItem)) {
        return nil;
    }

    [publicKey removeObjectForKey:(__bridge id)kSecValueData];
    [publicKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
    [publicKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
    [publicKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];

    // Now fetch the SecKeyRef version of the key
    SecKeyRef keyRef = nil;
    status = SecItemCopyMatching((__bridge CFDictionaryRef)publicKey, (CFTypeRef *)&keyRef);
    if(status != noErr){
        return nil;
    }
    return keyRef;
}

+ (NSData *)stripPublicKeyHeader:(NSData *)d_key{
    // Skip ASN.1 public key header
    if (d_key == nil) return(nil);

    unsigned long len = [d_key length];
    if (!len) return(nil);

    unsigned char *c_key = (unsigned char *)[d_key bytes];
    unsigned int  idx     = 0;

    if (c_key[idx++] != 0x30) return(nil);

    if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
    else idx++;

    // PKCS #1 rsaEncryption szOID_RSA_RSA
    static unsigned char seqiod[] =
    { 0x30,   0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
        0x01, 0x05, 0x00 };
    if (memcmp(&c_key[idx], seqiod, 15)) return(nil);

    idx += 15;

    if (c_key[idx++] != 0x03) return(nil);

    if (c_key[idx] > 0x80) idx += c_key[idx] - 0x80 + 1;
    else idx++;

    if (c_key[idx++] != '\0') return(nil);

    // Now make a new NSData from this buffer
    return ([NSData dataWithBytes:&c_key[idx] length:len - idx]);
}

+ (NSData *)RSAencryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
    const uint8_t *srcbuf = (const uint8_t *)[data bytes];
    size_t srclen = (size_t)data.length;

    size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
    void *outbuf = malloc(block_size);
    size_t src_block_size = block_size - 11;

    NSMutableData *ret = [[NSMutableData alloc] init];
    for(int idx=0; idx<srclen; idx+=src_block_size){
        //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
        size_t data_len = srclen - idx;
        if(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
                               );
        if (status != 0) {
            NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
            ret = nil;
            break;
        }else{
            [ret appendBytes:outbuf length:outlen];
        }
    }

    free(outbuf);
    CFRelease(keyRef);
    return ret;
}

/* END: Encryption with RSA public key */

#pragma mark - 使用私钥字符串解密

/* START: Decryption with RSA private key */

//使用私钥字符串解密
+ (NSString *)RSAdecryptString:(NSString *)str privateKey:(NSString *)privKey{
    if (!str) return nil;
    NSData *data = [[NSData alloc] initWithBase64EncodedString:str options:NSDataBase64DecodingIgnoreUnknownCharacters];
    data = [self RSAdecryptData:data privateKey:privKey];
    NSString *ret = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    return ret;
}

+ (NSData *)RSAdecryptData:(NSData *)data privateKey:(NSString *)privKey{
    if(!data || !privKey){
        return nil;
    }
    SecKeyRef keyRef = [self addPrivateKey:privKey];
    if(!keyRef){
        return nil;
    }
    return [self RSAdecryptData:data withKeyRef:keyRef];
}

+ (SecKeyRef)addPrivateKey:(NSString *)key{
    NSRange spos = [key rangeOfString:@"-----BEGIN RSA PRIVATE KEY-----"];
    NSRange epos = [key rangeOfString:@"-----END RSA PRIVATE KEY-----"];
    if(spos.location != NSNotFound && epos.location != NSNotFound){
        NSUInteger s = spos.location + spos.length;
        NSUInteger e = epos.location;
        NSRange range = NSMakeRange(s, e-s);
        key = [key substringWithRange:range];
    }
    key = [key stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@"\t" withString:@""];
    key = [key stringByReplacingOccurrencesOfString:@" "  withString:@""];

    // This will be base64 encoded, decode it.
    NSData *data = [MK_EncryOp base64DecodeWithData:key];
    data = [self stripPrivateKeyHeader:data];
    if(!data){
        return nil;
    }

    //a tag to read/write keychain storage
    NSString *tag = @"RSAUtil_PrivKey";
    NSData *d_tag = [NSData dataWithBytes:[tag UTF8String] length:[tag length]];

    // Delete any old lingering key with the same tag
    NSMutableDictionary *privateKey = [[NSMutableDictionary alloc] init];
    [privateKey setObject:(__bridge id) kSecClassKey forKey:(__bridge id)kSecClass];
    [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];
    [privateKey setObject:d_tag forKey:(__bridge id)kSecAttrApplicationTag];
    SecItemDelete((__bridge CFDictionaryRef)privateKey);

    // Add persistent version of the key to system keychain
    [privateKey setObject:data forKey:(__bridge id)kSecValueData];
    [privateKey setObject:(__bridge id) kSecAttrKeyClassPrivate forKey:(__bridge id)
     kSecAttrKeyClass];
    [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)
     kSecReturnPersistentRef];

    CFTypeRef persistKey = nil;
    OSStatus status = SecItemAdd((__bridge CFDictionaryRef)privateKey, &persistKey);
    if (persistKey != nil){
        CFRelease(persistKey);
    }
    if ((status != noErr) && (status != errSecDuplicateItem)) {
        return nil;
    }

    [privateKey removeObjectForKey:(__bridge id)kSecValueData];
    [privateKey removeObjectForKey:(__bridge id)kSecReturnPersistentRef];
    [privateKey setObject:[NSNumber numberWithBool:YES] forKey:(__bridge id)kSecReturnRef];
    [privateKey setObject:(__bridge id) kSecAttrKeyTypeRSA forKey:(__bridge id)kSecAttrKeyType];

    // Now fetch the SecKeyRef version of the key
    SecKeyRef keyRef = nil;
    status = SecItemCopyMatching((__bridge CFDictionaryRef)privateKey, (CFTypeRef *)&keyRef);
    if(status != noErr){
        return nil;
    }
    return keyRef;
}

+ (NSData *)stripPrivateKeyHeader:(NSData *)d_key{
    // Skip ASN.1 private key header
    if (d_key == nil) return(nil);

    unsigned long len = [d_key length];
    if (!len) return(nil);

    unsigned char *c_key = (unsigned char *)[d_key bytes];
    unsigned int  idx     = 22; //magic byte at offset 22

    if (0x04 != c_key[idx++]) return nil;

    //calculate length of the key
    unsigned int c_len = c_key[idx++];
    int det = c_len & 0x80;
    if (!det) {
        c_len = c_len & 0x7f;
    } else {
        int byteCount = c_len & 0x7f;
        if (byteCount + idx > len) {
            //rsa length field longer than buffer
            return nil;
        }
        unsigned int accum = 0;
        unsigned char *ptr = &c_key[idx];
        idx += byteCount;
        while (byteCount) {
            accum = (accum << 8) + *ptr;
            ptr++;
            byteCount--;
        }
        c_len = accum;
    }

    // Now make a new NSData from this buffer
    return [d_key subdataWithRange:NSMakeRange(idx, c_len)];
}

+ (NSData *)RSAdecryptData:(NSData *)data withKeyRef:(SecKeyRef) keyRef{
    const uint8_t *srcbuf = (const uint8_t *)[data bytes];
    size_t srclen = (size_t)data.length;

    size_t block_size = SecKeyGetBlockSize(keyRef) * sizeof(uint8_t);
    UInt8 *outbuf = malloc(block_size);
    size_t src_block_size = block_size;

    NSMutableData *ret = [[NSMutableData alloc] init];
    for(int idx=0; idx<srclen; idx+=src_block_size){
        //NSLog(@"%d/%d block_size: %d", idx, (int)srclen, (int)block_size);
        size_t data_len = srclen - idx;
        if(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
                               );
        if (status != 0) {
            NSLog(@"SecKeyEncrypt fail. Error Code: %d", status);
            ret = nil;
            break;
        }else{
            //the actual decrypted data is in the middle, locate it!
            int idxFirstZero = -1;
            int idxNextZero = (int)outlen;
            for ( int i = 0; i < outlen; i++ ) {
                if ( outbuf[i] == 0 ) {
                    if ( idxFirstZero < 0 ) {
                        idxFirstZero = i;
                    } else {
                        idxNextZero = i;
                        break;
                    }
                }
            }
            [ret appendBytes:&outbuf[idxFirstZero+1] length:idxNextZero-idxFirstZero-1];
        }
    }
    free(outbuf);
    CFRelease(keyRef);
    return ret;
}

@end