How can we encrypt bytes through DES/CBC/NOPADDING in Objective C? - ios

Question

I am trying to encrypt bytes data through DES/CBS/NOPADDING algorithm but unable to get correct output. What I have tried is given below in code. Please have a look and suggest.
#import "STEncryptViewController.h"
#import <CommonCrypto/CommonCryptor.h>
#import "STEncryptorDES.h"
#import "NSData+Base64.h"
#import <CommonCrypto/CommonDigest.h>
#define KEY #"MY_TEST_KEY"
#interface STEncryptViewController ()
#end
#implementation STEncryptViewController
#synthesize message;
#synthesize encrypted;
#synthesize decrypted;
#synthesize key;
#synthesize outputMessage;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
}
- (IBAction)encrypt:(id)sender
{
const unsigned char bytes[] = {65,17,17,17,17,17,17,17};
NSData *data = [NSData dataWithBytes:bytes length:sizeof(bytes)];
NSString *str = self.key.text;
NSData* data12 = [str dataUsingEncoding:NSUTF8StringEncoding];
NSUInteger len = str.length;
uint8_t *bytes1 = (uint8_t *)[data12 bytes];
NSMutableString *result = [NSMutableString stringWithCapacity:len * 3];
// [result appendString:#"["];
//Key convertion
int i = 0;
while(i < len){
if (i) {
[result appendString:#","];
}
[result appendFormat:#"%d", bytes1[i]];
i++;
}
// [result appendString:#"]"];
NSLog (#"String is %#",str);
NSLog (#"Byte array is %#",result);
//
Byte iv1 [] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
Byte iv [] = {1, 35, 69, 103, -119, -85, -51, -17};
NSData *ivData = [NSData dataWithBytes:iv length:sizeof(iv)];
NSData *encryptedData = [STEncryptorDES encryptData1:data key:[NSData dataWithBytes:iv1 length:sizeof(iv1)] iv:ivData];
NSLog(#"encrypted : %#", [encryptedData base64EncodedString]);
self.outputMessage.text = [NSString stringWithFormat:#"Encrypted String ::>> %#",[encryptedData base64EncodedString]];
[self doCipher:nil enc:kCCEncrypt];
}
- (NSData *)md5DataFromString:(NSString *)input
{
const char *cStr = [input UTF8String];
unsigned char digest[16];
CC_MD5( cStr, strlen(cStr), digest ); // This is the md5 call
return [NSData dataWithBytes:digest length:CC_MD5_DIGEST_LENGTH];
}
- (IBAction)decrypt:(id)sender
{
NSData *valueData = [self hexToBytes:self.decrypted.text];
NSData *keyData = [self md5DataFromString:self.key.text];
Byte iv [] = {1, 35, 69, 103, -119, -85, -51, -17};
NSData *ivData = [NSData dataWithBytes:iv length:sizeof(iv)];
NSData *decryptedData = [STEncryptorDES decryptData:valueData key:keyData iv:ivData];
NSLog(#"decrypted : %#", [[NSString alloc] initWithData:decryptedData encoding:NSASCIIStringEncoding]);
self.outputMessage.text = [NSString stringWithFormat:#"Decrypted String ::>> %#", [[NSString alloc] initWithData:decryptedData encoding:NSASCIIStringEncoding]];
}
- (NSString*)doCipher:(NSString*)plainText enc:(CCOperation)encryptOrDecrypt{
NSData *key123 = [self hexToBytes:#"MY_TEST_KEY"];
const void *vplainText;
size_t plainTextBufferSize;
if (encryptOrDecrypt == kCCDecrypt)
{
NSData *EncryptData = [self hexToBytes:#"5454545454545454"];
// NSData *EncryptData =[NSData dataWithBase64EncodedString:plainText];
plainTextBufferSize = [EncryptData length];
vplainText = [EncryptData bytes];
}
else
{
plainTextBufferSize = [plainText length];
vplainText = (const void *) [plainText UTF8String];
}
CCCryptorStatus ccStatus;
uint8_t *bufferPtr = NULL;
size_t bufferPtrSize = 0;
size_t movedBytes = 0;
// uint8_t ivkCCBlockSize3DES;
bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
memset((void *)bufferPtr, 0x0, bufferPtrSize);
unsigned char cKey[FBENCRYPT_KEY_SIZE];
bzero(cKey, sizeof(cKey));
[key123 getBytes:cKey length:FBENCRYPT_KEY_SIZE];
//unsigned char result1[24]= {0,0,0,0,0,0,0,0,0,0,0,00,0,0,0,0,0,0,0,00,00,00,00,0};
unsigned char IV3[8]={1, 35, 69, 103, -119, -85, -51, -17};
uint8_t iv[kCCBlockSize3DES];
memset((void *) iv, 0x0, (size_t) sizeof(iv));
ccStatus = CCCrypt(encryptOrDecrypt,
kCCAlgorithm3DES,
0x0000 ,
cKey, //"123456789012345678901234", //key
kCCKeySize3DES,
IV3 , //iv,
vplainText, //plainText,
plainTextBufferSize,
(void *)bufferPtr,
bufferPtrSize,
&movedBytes);
//if (ccStatus == kCCSuccess) NSLog(#"SUCCESS");
/*else*/ if (ccStatus == kCCParamError) return #"PARAM ERROR";
else if (ccStatus == kCCBufferTooSmall) return #"BUFFER TOO SMALL";
else if (ccStatus == kCCMemoryFailure) return #"MEMORY FAILURE";
else if (ccStatus == kCCAlignmentError) return #"ALIGNMENT";
else if (ccStatus == kCCDecodeError) return #"DECODE ERROR";
else if (ccStatus == kCCUnimplemented) return #"UNIMPLEMENTED";
NSString *result;
if (encryptOrDecrypt == kCCDecrypt)
{
result = [ [NSString alloc] initWithData: [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes] encoding:NSASCIIStringEncoding];
}
else
{
NSData *myData = [NSData dataWithBytes:(const void *)bufferPtr length:(NSUInteger)movedBytes];
NSLog(#"data is: %#", myData);
// result = [NSData base64StringFromData:myData length:myData.length];
// result = [[NSString alloc]initWithData:myData encoding:NSUTF8StringEncoding];
result = nil;
}
return result;
}
-(NSData*)hexToBytes:(NSString *)hex {
NSString *safeStr = [hex stringByReplacingOccurrencesOfString:#"0" withString:#"A"];
NSMutableData* data = [NSMutableData data];
int idx;
for (idx = 0; idx+2 <= safeStr.length; idx+=2) {
NSRange range = NSMakeRange(idx, 2);
NSString* hexStr = [safeStr substringWithRange:range];
NSScanner* scanner = [NSScanner scannerWithString:hexStr];
unsigned int intValue;
[scanner scanHexInt:&intValue];
[data appendBytes:&intValue length:1];
}
NSLog(#"%lu",(unsigned long)data.hash);
return data;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
This was my all effort. Currently it is working but not expected output getting. Please suggest me what am I missing here?

Answer 1

One glaring error is that STEncryptorDES is used and is specifies padding but the question states that padding should be used.
Observations:
- You call doCipher with nil and do not use it's return value, delete the unneeded/unused code from the question.
- There is a lot of code to perform a rather simple operation.
- It seems that the test data variable is named iv1, use a better name if that is correct.
- DES should not be used for new work, only when necessary to interoperate with existing work, it is not very secure. New work should use AES.
- #synthesize has not been needed for several years.

Answer 2

In cryptography "DESede/CBC/NoPadding" use following code might be help for you.
Byte iv [] = {1, 35, 69, 103, -119, -85, -51, -17};
NSData *ivData = [NSData dataWithBytes:iv length:sizeof(iv)];
NSData key = ["MY_TEST_KEY" dataUsingEncoding:NSUTF8StringEncoding]
char cKey[key.length];
bzero(cKey, sizeof(cKey));
[key getBytes:cKey length:key.length];
// setup iv
char cIv[kCCBlockSizeDES];
bzero(cIv, kCCBlockSizeDES);
if (ivData) {
[ivData getBytes:cIv length:kCCBlockSizeDES];
}
// setup output buffer
size_t bufferSize = [data length] + kCCBlockSizeDES;
void *buffer = malloc(bufferSize);
// do encrypt
size_t encryptedSize = 0;
CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt,
kCCAlgorithm3DES,
ccNoPadding,
cKey,
key.length,
cIv,
[data bytes],
[data length],
buffer,
bufferSize,
&encryptedSize);
if (cryptStatus == kCCSuccess) {
resultData = [NSData dataWithBytes:buffer length:encryptedSize];
free(buffer);
} else {
free(buffer);
NSLog(#"[ERROR] failed to encrypt|CCCryptoStatus: %d", cryptStatus);
return nil;
}