本文介绍了OSX AES加密不工作的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
在我的应用程序中，我需要在通过网络发送文件之前对其进行加密，而另一端则会得到解密，这是我的代码， - （void）doEncryptTest：（NSString *）pFileName {
//读取NSData;
NSStringEncoding encoding = NSUTF8StringEncoding;
NSString * pFileContent = @xaaaaaaxxaaaaaax;
NSString * pKey = @01234567012345670123456701234567;
NSData * pData = [pFileContent dataUsingEncoding：encoding];
NSData * pEncryptedData = [pData AES256EncryptWithKey：pKey];
NSData * decryptpted = [pEncryptedData AES256DecryptWithKey：pKey Data：pEncryptedData];
NSString * pDecryptedDataStr = [[NSString alloc] initWithData：decryptpted
encoding：encoding];
}
只有当数据大小为16字节，在实时情况下，当我发送大小为151186字节的文件时，[pEncryptedData]的大小为15200，实际上解密数据的大小与原始数据相同，但是pDecryptedDataStr为空，任何猜测发生什么问题，
请参考下面的加密和解密功能，
int keySize = kCCKeySizeAES256;
int padding = kCCOptionPKCS7Padding;
char ivKey [16] = {0,0,0,0，
0,0,0,0，
0,0,0,0，
0,0 ，0,0};
////////////// *加密* ///////////////////
- （NSData *）AES256EncryptWithKey ：（NSString *）键{
//'key'应为AES256的32个字节，否则将为null-padding
char keyPtr [keySize + 1]; //用于终结器的空间（未使用）
bzero（keyPtr，sizeof（keyPtr））; //填充零（用于填充）
//获取密钥数据
[key getCString：keyPtr maxLength：sizeof（keyPtr）encoding：NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//查看文档：对于块密码，输出大小始终小于或等于输入大小加上一个块的大小。
//这就是为什么我们需要在这里添加一个块的大小
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void * buffer = malloc（bufferSize）;
char ivVector [kCCBlockSizeAES128 + 1];
//获取密钥数据
[key getCString：ivVector maxLength：sizeof（ivVector）encoding：NSUTF8StringEncoding];
bzero（ivVector，sizeof（ivVector））; //填充零（用于填充）
const void * iv = NULL;
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt（kCCEncrypt，kCCAlgorithmAES128，padding，
keyPtr，keySize，
ivKey / *初始化向量（可选）* /，
[self bytes]，dataLength，/ * input * /
buffer，bufferSize，/ * output * /
& numBytesEncrypted）;
if（cryptStatus == kCCSuccess）
{
//返回的NSData获取缓冲区的所有权，并在释放后释放它
return [NSData dataWithBytesNoCopy：buffer length：numBytesEncrypted] ;
}
free（buffer）; //释放缓冲区
return nil;
}
- （NSData *）AES256DecryptWithKey :( NSString *）key数据：（NSData *）EncryptedData {
bool same = [self isEqualToData：EncryptedData];
//'key'应为AES256的32个字节，否则将为零填充
char keyPtr [keySize + 1]; //用于终结器的空间（未使用）
bzero（keyPtr，sizeof（keyPtr））; //填充零（用于填充）
//获取密钥数据
[key getCString：keyPtr maxLength：sizeof（keyPtr）encoding：NSUTF8StringEncoding];
NSUInteger dataLength = [EncryptedData length];
//查看文档：对于块密码，输出大小始终小于或等于输入大小加上一个块的大小。
//这就是为什么我们需要在这里添加一个块的大小
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void * buffer = malloc（bufferSize）;
const void * iv = NULL;
char ivVector [kCCBlockSizeAES128 + 1];
//获取密钥数据
[key getCString：ivVector maxLength：sizeof（ivVector）encoding：NSUTF8StringEncoding];
bzero（ivVector，sizeof（ivVector））; //填充零（用于填充）
size_t numBytesDecrypted = 0;
NSData * output_decrypt = [[NSData alloc] init];
CCCryptorStatus cryptStatus = CCCrypt（kCCDecrypt，kCCAlgorithmAES128，padding，
keyPtr，keySize，
ivKey / *初始化向量（可选）* /，
[加密数据字节]，dataLength， * input * /
buffer，bufferSize，// bufferSize，/ * output * /
& numBytesDecrypted）;
output_decrypt = [NSMutableData dataWithBytesNoCopy：buffer length：numBytesDecrypted];
same = [self isEqualToData：output_decrypt];
if（cryptStatus == kCCSuccess）
{
//返回的NSData取得缓冲区的所有权，并在释放后释放
NSData * pData = [[ NSData alloc] initWithBytes：buffer length：numBytesDecrypted];
return pData;
}
free（buffer）; //释放缓冲区
return nil;
}
解决方案
这是问题，
output_decrypt = [NSMutableData dataWithBytesNoCopy：buffer length：numBytesDecrypted];
same = [self isEqualToData：output_decrypt];
if（cryptStatus == kCCSuccess）
{
//返回的NSData取得缓冲区的所有权，并在释放后释放
** NSData * pData = [[NSData alloc] initWithBytes：buffer length：numBytesDecrypted]; **
return pData;
}
output_decrypt = [NSMutableData dataWithBytesNoCopy：buffer length：numBytesDecrypted];
same = [self isEqualToData：output_decrypt];
if（cryptStatus == kCCSuccess）
{
//返回的NSData取得缓冲区的所有权，并在释放后释放
return output_decrypt ;
}
不知道为什么会造成问题我需要更改返回类型，并在调用函数中执行一些处理以释放内存。
In my application, i need to encrypt the file before sending it over the network and on the other end, it will get decrypt, This is my code,
-(void)doEncryptTest:(NSString *)pFileName{
// read the NSData;
NSStringEncoding encoding =NSUTF8StringEncoding;
NSString *pFileContent = @"xaaaaaaxxaaaaaax";
NSString *pKey = @"01234567012345670123456701234567";
NSData *pData = [pFileContent dataUsingEncoding:encoding];
NSData *pEncryptedData = [pData AES256EncryptWithKey:pKey];
NSData *decrypted=[pEncryptedData AES256DecryptWithKey:pKey Data:pEncryptedData];
NSString* pDecryptedDataStr = [[NSString alloc] initWithData:decrypted
encoding:encoding];
}
This is working fine , only and only if Data size is 16 byte, in real time case, when i sent the file of size 151186 bytes, size of [pEncryptedData] is 15200 , and in fact size of decrypted data is same as original data,But pDecryptedDataStr is blank, any guess what is going wrong,please refer below, Encryption and decryption function,
int keySize = kCCKeySizeAES256;
int padding = kCCOptionPKCS7Padding;
char ivKey[16]={0,0,0,0,
0,0,0,0,
0,0,0,0,
0,0,0,0};
//////////////*Encryption*///////////////////
- (NSData *)AES256EncryptWithKey:(NSString *)key{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[keySize + 1]; // room for terminator (unused)
bzero( keyPtr, sizeof( keyPtr ) ); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof( keyPtr ) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [self length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc( bufferSize );
char ivVector[kCCBlockSizeAES128+1];
// fetch key data
[key getCString:ivVector maxLength:sizeof( ivVector ) encoding:NSUTF8StringEncoding];
bzero( ivVector, sizeof( ivVector ) ); // fill with zeroes (for padding)
const void *iv=NULL;
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt( kCCEncrypt, kCCAlgorithmAES128, padding,
keyPtr, keySize,
ivKey /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesEncrypted );
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
}
free( buffer ); //free the buffer
return nil;
}
- (NSData *)AES256DecryptWithKey:(NSString *)key Data:(NSData*)EncryptedData{
bool same =[self isEqualToData:EncryptedData];
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[keySize+1]; // room for terminator (unused)
bzero( keyPtr, sizeof( keyPtr ) ); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof( keyPtr ) encoding:NSUTF8StringEncoding];
NSUInteger dataLength = [EncryptedData length];
//See the doc: For block ciphers, the output size will always be less than or
//equal to the input size plus the size of one block.
//That's why we need to add the size of one block here
size_t bufferSize = dataLength +kCCBlockSizeAES128;
void *buffer = malloc( bufferSize );
const void *iv=NULL;
char ivVector[kCCBlockSizeAES128+1];
// fetch key data
[key getCString:ivVector maxLength:sizeof( ivVector ) encoding:NSUTF8StringEncoding];
bzero( ivVector, sizeof( ivVector ) ); // fill with zeroes (for padding)
size_t numBytesDecrypted = 0;
NSData *output_decrypt = [[NSData alloc] init];
CCCryptorStatus cryptStatus = CCCrypt( kCCDecrypt, kCCAlgorithmAES128, padding,
keyPtr, keySize,
ivKey /* initialization vector (optional) */,
[EncryptedData bytes], dataLength, /* input */
buffer,bufferSize ,//bufferSize, /* output */
&numBytesDecrypted );
output_decrypt = [NSMutableData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
same =[self isEqualToData:output_decrypt];
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
NSData *pData = [[NSData alloc]initWithBytes:buffer length:numBytesDecrypted];
return pData;
}
free( buffer ); //free the buffer
return nil;
}
解决方案
Thanks for looking at this, this was the problem,
output_decrypt = [NSMutableData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
same =[self isEqualToData:output_decrypt];
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
**NSData *pData = [[NSData alloc]initWithBytes:buffer length:numBytesDecrypted];**
return pData;
}
and solutions was;
output_decrypt = [NSMutableData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
same =[self isEqualToData:output_decrypt];
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
return output_decrypt;
}
Not sure, why it was causing problem, of-course i need to change return type and do some handling in the calling function to release the memory.
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