iOS开发之Objective-c的AES加密和解密算法的实现

//
//NSData+AES256.h
//

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>

@interface NSData(AES256)
-(NSData *) aes256_encrypt:(NSString *)key;
-(NSData *) aes256_decrypt:(NSString *)key;
@end

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

@implementation NSData(AES256)

- (NSData *)aes256_encrypt:(NSString *)key   //加密
{
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;
}

- (NSData *)aes256_decrypt:(NSString *)key   //解密
{
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 +AES256.h
//

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonDigest.h>
#import <CommonCrypto/CommonCryptor.h>

#import "NSData+AES256.h"

@interface NSString(AES256)

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

@end

//
//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