ios decrypt base64 encoded string using des ecb - ios

Question

I am trying to decrypt a string that was first encrypted using des in ecb mode, and then encoded in base64.
This is my code:
+ (NSString *)decrypt:(NSString *)encryptedText
{
NSString *key = #"12345678";
NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:encryptedText options:0];
size_t numBytesDecrypted = 0;
size_t bufferSize = [decodedData length] + kCCBlockSizeDES;
void *buffer = malloc(bufferSize);
char keyPtr[kCCKeySizeDES+1]; // room for terminator (unused)
bzero(keyPtr, sizeof(keyPtr));
[key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt,
kCCAlgorithmDES,
kCCOptionPKCS7Padding | kCCOptionECBMode,
keyPtr,
kCCKeySizeAES256,
NULL /* initialization vector (optional) */,
[decodedData bytes], [decodedData length], /* input */
buffer, bufferSize, /* output */
&numBytesDecrypted);
NSData *val = [NSData dataWithBytesNoCopy:buffer length:numBytesDecrypted];
return [[NSString alloc] initWithData:val encoding:NSUTF8StringEncoding];
}
However I am getting a nil string in return...any ideas?

Answer 1

You are using DES but are specifying the key size as: kCCKeySizeAES256 in the call to: CCCrypt.
There are so many things wrong with this code from a security standpoint, don't use this in a real app. This is no longer best practice. Among other things the password should be converted to key with a Password-Based Key Derivation Function such as PBKDF2. Also using DES and ECB mode is a weaknesses.