Objective-C的AES加密和解密算法

NSData分类

• NSData+AES256.h

//
// NSData+AES256.h
//

#import  
#import  
#import  

@interface NSData(AES256)

- (NSData *)aes256_encrypt:(NSString *)key;
- (NSData *)aes256_decrypt:(NSString *)key;

@end

• NSData+AES256.m

//
// NSData+AES256.m
//#import "NSData+AES256.h"

@implementation NSData (AES256)

/** 加密 */
- (NSData*)aes256_encrypt:(NSString *)key
{
    char keyPtr[kCCKeySizeAES256 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [self length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void *buffer = malloc(bufferSize);
    size_t numBytesEncrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding | kCCOptionECBMode, keyPtr, kCCBlockSizeAES128, NULL, [self bytes], dataLength, buffer, bufferSize, &numBytesEncrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
    }
    free(buffer);
    return nil;
}

/** 解密 */
- (NSData*)aes256_decrypt:(NSString *)key
{
    char keyPtr[kCCKeySizeAES256 + 1];
    bzero(keyPtr, sizeof(keyPtr));
    [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
    NSUInteger dataLength = [self length];
    size_t bufferSize = dataLength + kCCBlockSizeAES128;
    void* buffer = malloc(bufferSize);
    size_t numBytesDecrypted = 0;
    CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding | kCCOptionECBMode, keyPtr, kCCBlockSizeAES128, NULL, [self bytes], dataLength, buffer, bufferSize, &numBytesDecrypted);
    if (cryptStatus == kCCSuccess) {
        return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
    }
    free(buffer);
    return nil;
}

@end

---

NSString分类

需要导入NSData+AES256.h

• NSString +AES256.h

//
// NSString +AES256.h
//

#import 
#import 
#import 
#import "NSData+AES256.h"

@interface NSString (AES256)

- (NSString *)aes256_encrypt:(NSString *)key; 
- (NSString *)aes256_decrypt:(NSString *)key; 

@end

• NSString +AES256.m

// 
// NSString +AES256.h 
//

@implementation NSString (AES256)

- (NSString *)aes256_encrypt:(NSString *)key
{
    const char *cstr = [self cStringUsingEncoding:NSUTF8StringEncoding];
    NSData *data = [NSData dataWithBytes:cstr length:self.length]; //对数据进行加密
    NSData *result = [data aes256_encrypt:key]; //转换为2进制字符串
    if (result && result.length > 0) {
        Byte *datas = (Byte*)[result bytes];
        NSMutableString *output = [NSMutableString stringWithCapacity:result.length * 2];
        for (int i = 0; i < result.length; i++) {
            [output appendFormat:@"%02x", datas[i]];
        }
        return output;
    }
    return nil;
}

- (NSString *)aes256_decrypt:(NSString *)key
{ 
    //转换为2进制Data
    NSMutableData *data = [NSMutableData dataWithCapacity:self.length / 2];
    unsigned char whole_byte;
    char byte_chars[3] = { '\0', '\0', '\0' };
    int i;
    for (i = 0; i < [self length] / 2; i++) {
        byte_chars[0] = [self characterAtIndex:i * 2];
        byte_chars[1] = [self characterAtIndex:i * 2 + 1];
        whole_byte = strtol(byte_chars, NULL, 16);
        [data appendBytes:&whole_byte length:1];
    } 
    //对数据进行解密
    NSData *result = [data aes256_decrypt:key];
    if (result && result.length > 0) { 
        return [[NSString alloc] initWithData:result encoding:NSUTF8StringEncoding]autorelease];
    }
    return nil;
}

@end