Objective-C AES加解密

在线加解密：https://blog.zhengxianjun.com/online-tool/crypto/aes/

一、AES简介

高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法。AES是一个对称分组密码算法，旨在取代DES成为广泛使用的标准。根据使用的密码长度，AES最常见的有3种方案，用以适应不同的场景要求，分别是AES-128、AES-192和AES-256。

二、算法描述

AES1

AES2
=
AES算法较为复杂这里不再赘述，如有兴趣可点击描述出处查看更多资料。

三、算法实现

@implementation CATSecurity

#pragma mark --
#pragma mark -- AES

/**
*  get data's aes256 encrypt data
*
*  @param data source data
*  @param key  key for encrypt/decrypt  !!!key length must be 16
*
*  @return aes256 encrypt data
*/
+(NSData *)aes256EncryptWithData:(NSData *)data key:(NSString *)key{
if (!key || key.length !=16) {
NSLog(@"key length must be 16");
return nil;
}
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = data.length;
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
data.bytes, dataLength,
buffer, bufferSize,
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free(buffer);
return nil;
}

/**
*  get source data from aes256 encrypt data
*
*  @param data aes256 encrypt data
*  @param key  key for encrypt/decrypt  !!!key length must be 16
*
*  @return source data
*/
+(NSData *)aes256DecryptWithData:(NSData *)data key:(NSString *)key{
if (!key || key.length !=16) {
NSLog(@"key length must be 16");
return nil;
}
char keyPtr[kCCKeySizeAES256+1];
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = data.length;
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr, kCCBlockSizeAES128,
NULL,
data.bytes, dataLength,
buffer, bufferSize,
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer);
return nil;
}

/**
*  get string's aes256 encrypt data
*
*  @param string source string
*  @param key  key for encrypt/decrypt  !!!key length must be 16
*
*  @return aes256 encrypt data
*/
+(NSData*)aes256EncryptWithString:(NSString*)string key:(NSString *)key{
if (!key || key.length !=16) {
NSLog(@"key length must be 16");
return nil;
}
NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
NSData *encryptedData = [self aes256EncryptWithData:data key:key];
return encryptedData;
}

/**
*  get source string from aes256 encrypt data
*
*  @param data aes256 encrypt data
*  @param key  key for encrypt/decrypt  !!!key length must be 16
*
*  @return source string
*/
+(NSString*)aes256DecryptStringWithData:(NSData *)data key:(NSString *)key{
if (!key || key.length !=16) {
NSLog(@"key length must be 16");
return nil;
}
NSData *decryData = [self aes256DecryptWithData:data key:key];
NSString *string = [[NSString alloc] initWithData:decryData encoding:NSUTF8StringEncoding];
return string;
}

@end

四、补充

由于iOS、java的平台差异，AES的加密算法存在兼容性问题(iOS的AES Padding只支持ccPKCS7Padding, ccNoPadding)，为了使用方便，我找了一份可兼容的Java的代码并做了测试，详见工程的java目录。

作者：CatchZeng
链接：http://www.jianshu.com/p/1247e946c61f
來源：简书
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