I'm having a hard time decrypting NSData with NSData key. While decrypting with NSString everything works fine, yet with data as key, the method returns null NSData, eventhough status is ok, and key is also correct for that data. Here is my call
NSData *decrypted = [AES AES128DecryptWithKey:data key:mute];
NSLog(#"DECRYPTED >> %#", decrypted);
And my method
+ (NSData*)AES128DecryptWithKey:(NSData*) data key:(NSData*)key {
NSUInteger dataLength = [data length];
NSLog(#"trying to decrypt >> %# with key >> %#", data, key );
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void* buffer = malloc(bufferSize);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
[key bytes], kCCKeySizeAES128,
NULL /* initialization vector (optional) */,
[data bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted);
NSLog(#"cryptstatus %d", cryptStatus);
if (cryptStatus == kCCSuccess)
{
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer); //free the buffer;
return nil;
}
NSLog output:
trying to decrypt >> <152f052e 79436003 7a9c1a59 3b82f1c4>
with key >> <1b510e76 ac0000a1 027af26a e25ad24a>
cryptstatus 0
DECRYPTED >> <>
Looked into RNEncryptor, yet it only has aes256, while i need 128. Any ideas?
It could be that the single byte block only contains padding bytes. In that case zero bytes would be the expected outcome.
This is not the case for your ciphertext, in your case no padding was applied during encryption, so you will get a failure when you try and unpad the data.
Related
I have some Encryption and Decryption class methods in my application. I can encrypt 'data' using 'key' and it works great. I can write that data to disk and then read the data in at a later time using the application and call decryptWithKey to decrypt the data block. Everything works great. However, if I include this .m class file into another application, compile that application and try to decrypt that same data which was encrypted with the first application, the CCCrypt(decrypt) call fails...well, not exactly, it returns Success but the data is not decrypted. I have compared the data and key values in both applications and they are identical, down to the byte.
Any ideas?
+(BOOL)encryptWithKey:(NSMutableData*)data withKey:(NSString *)key
{
CCCryptorStatus result = kCCSuccess;
#try
{
char keyPtr1[kCCKeySizeAES256+1]; // room for terminator (unused)
bzero( keyPtr1, sizeof(keyPtr1) ); // fill with zeroes (for padding)
[key getCString: keyPtr1 maxLength: sizeof(keyPtr1) encoding: NSUTF8StringEncoding];
size_t numBytesEncrypted = 0;
size_t dataInLength = [data length];
size_t dataOutLength = 18*dataInLength;
[data setLength:dataOutLength];
result = CCCrypt( kCCEncrypt,kCCAlgorithmAES128,kCCOptionPKCS7Padding,
(const void*)keyPtr1, kCCKeySizeAES256, 0 /* initialization vector (optional) */,
[data mutableBytes], dataInLength, /* input */
[data mutableBytes], dataOutLength, /* output */
&numBytesEncrypted );
[data setLength:numBytesEncrypted];
}
#catch (NSException *exception)
{
WDCATCH(exception);
}
return ( result == kCCSuccess );
}
+(BOOL)decryptWithKey:(NSMutableData*)data plaintext:(NSString**)plaintext withKey:(NSString *)key
{
CCCryptorStatus result = kCCSuccess;
#try
{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+1]; // room for terminator (unused)
char szPlaintext[1024]={0};
bzero( keyPtr, sizeof(keyPtr) ); // fill with zeroes (for padding)
[key getCString: keyPtr maxLength: sizeof(keyPtr) encoding: NSUTF8StringEncoding];
size_t numBytesEncrypted = 0;
result = CCCrypt( kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
(const void*)keyPtr, kCCKeySizeAES256,
0 /* initialization vector (optional) */,
[data mutableBytes], [data length], /* input */
szPlaintext,1024,// [data mutableBytes], dataOutLength, /* output */
&numBytesEncrypted );
if (result == kCCSuccess)
{
szPlaintext[numBytesEncrypted] = 0;
*plaintext = [[NSString alloc] initWithFormat:#"%s",szPlaintext];
}
}
#catch (NSException *exception)
{
WDCATCH(exception);
} return ( result == kCCSuccess );
}
I'm not an Objective-C expert, but char szPlaintext[1024]={0}; in the decryptWithKey seems very suspicious to me. First you allocate 1024 bytes, but then you assign the pointer to an array containing the element 0? The generation of plaintext as a string looks pretty suspicious as well, but it probably works for ASCII encoded plaintext (?).
I have been struggling with this problem for several days now and i can't seem to figure it out
I tried using CCCrypt to decrypt an encrypted string, I have the encrypted string encoded with Base64 encode, I have the key and the iv. The encryption is AES256 CBC with PKCS7Padding.
This is the code i am using right now:
- (NSData *)AES256DecryptWithKey:(NSString *)key
{
char keyPtr[kCCKeySizeAES128+1];
bzero(keyPtr, sizeof(keyPtr));
NSUInteger dataLength = [self length];
size_t bufferSize = dataLength + kCCBlockSizeAES128;
void *buffer = malloc( bufferSize );
unsigned char *iv = [#"IV String" cStringUsingEncoding:NSUTF8StringEncoding];
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
kCCAlgorithmAES128,
kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
iv,
[self bytes],
dataLength,
buffer,
bufferSize,
&numBytesDecrypted);
if( cryptStatus == kCCSuccess )
{
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free( buffer );
return nil;
}
But cryptStatus keeps returning 0 and I couldn't find a way to figure out why.
What am i doing wrong?
Thanks in advance!
I try to use CCCrypt method, but it has different result from XCode4 and XCode5
- (NSData *)AES256DecryptWithKey:(NSString *)key
{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES256+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 );
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt( kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[self bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted );
if( cryptStatus == kCCSuccess )
{
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free( buffer ); //free the buffer
return nil;
}
when I call this method with this lines ... different result
NSString *password = #"E7VRcIXn8yb2Ab+t/in9UzRof6vOpOYebgKbpt1GOcfDF8rpc5nZXngx1G8QfbDqsVrwZw26609GVwruUBrOirCI/WUT8U87fbD6lSy/zPwFIYC113LgXIEylYgzIWO4";
NSString *pwd = [password AES256DecryptWithKey: #"abcd"];
if (pwd) {
NSString *checkKey = #"0sSBf7Ncyov+uzvDikOBiA==";
NSString *uncryptChk = [checkKey AES256DecryptWithKey: pwd];
In XCode4 the result is "abcd", whereas in XCode5 the result is "".
Ran into this issue myself. it seems they fixed a bug from iOS6 to iOS7 regarding [NSString keyCString:maxLength:encoding] The old method on iOS6 would cut off part of the buffer to fill the keyPtr.
An easy fix would be to increase the keyPTr size to
char keyPtr = kCCKeySizeAES256 * 2 + 1;
However keep in mind that when you upgrade apps form 6 to 7, while it should work. the keyCString truncates the length to match the size of keyPtr. and replaces the first character with 0. So to make sure that it works on both platforms. Add the above code, and set keyPtr[0] = 0;
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;
}
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.
My question is I need to use the following hexadecimal key to encrypt but it assumes it as a string?
key = 0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11,0x11
I had tried using [key bytes] instead of keyptr in the CCrypt function but it does't work...
- (NSData *)AES128EncryptWithKey:(NSString *)key theData:(NSData *)Data {
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES128]={'1'};; // room for terminator (unused) // oorspronkelijk 256
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
NSLog(#"keyPtr %s",keyPtr);
NSUInteger dataLength = [Data 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);
size_t numBytesEncrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionECBMode,
keyPtr,
kCCKeySizeAES128, // oorspronkelijk 256
nil, /* initialization vector (optional) */
[Data bytes],
dataLength, /* input */
buffer,
bufferSize, /* output */
&numBytesEncrypted);
if (cryptStatus == kCCSuccess) {
NSLog(#"Encrypt SUCCESS");
//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 *)AES128DecryptWithKey:(NSString *)key theData:(NSData *)Data{
// 'key' should be 32 bytes for AES256, will be null-padded otherwise
char keyPtr[kCCKeySizeAES128+1]; // room for terminator (unused) // oorspronkelijk 256
bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
// fetch key data
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSASCIIStringEncoding];
NSUInteger dataLength = [Data 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);
size_t numBytesDecrypted = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionECBMode+kCCOptionPKCS7Padding,
keyPtr, kCCKeySizeAES128, // oorspronkelijk 256
NULL /* initialization vector (optional) */,
[Data bytes], dataLength, /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted);
if (cryptStatus == kCCSuccess) {
NSLog(#"Decrypt SUCCESS");
//the returned NSData takes ownership of the buffer and will free it on deallocation
return [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
}
free(buffer); //free the buffer;
return nil;
}
You can use NSScanner, like this:
NSString *keyStr = #"0x11,0x12,0x13,0x14,0x13,0x1a,0x1b,0x1c,0x1f,0x11,0x11,0x11,0x11,0x11,0x11,0xfe";
NSScanner *scan = [NSScanner scannerWithString:keyStr];
[scan setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:#","]];
unsigned int tmp;
char key[16];
for (int i = 0 ; i != 16 ; i++) {
[scan scanHexInt:&tmp];
key[i] = (char)tmp;
}
At this point, the array key contains 16 bytes of your key converted from hex to bytes.