3DES encryption in iOS does not seem to encrypt last block - ios

Question

I have the following code in objective-c
NSString* v_plainText = #"1234567890123456789012345678";
NSString* plainText = (const void *) [v_plainText UTF8String];
size_t plainTextBufferSize = [v_plainText length];
size_t bufferPtrSize = (plainTextBufferSize + kCCBlockSize3DES) & ~(kCCBlockSize3DES - 1);
size_t movedBytes = 0;
uint8_t *bufferPtr = malloc( bufferPtrSize * sizeof(uint8_t));
Byte iv[8] = {0,0,0,0,0,0,0,0};
NSString *key = (const void *) [#"12345678ABCDEFGH!##$%^&*" UTF8String];
CCCryptorStatus ccStatus;
ccStatus = CCCrypt(kCCEncrypt,
kCCAlgorithm3DES,
kCCOptionPKCS7Padding & kCCModeCBC,
key,
kCCKeySize3DES,
iv,
plainText,
plainTextBufferSize,
(void *)bufferPtr, // output
bufferPtrSize,
&movedBytes);
NSData* result = [NSData dataWithBytes:(const void*)bufferPtr length:(NSUInteger)movedBytes];
NSString* str = [result base64EncodedStringWithOptions:0];
This gives this result:
geHFnvoept2aKiruo6InSvc7WVPdHNq2
When I run simular code in .NET it gives me this result:
geHFnvoept2aKiruo6InSvc7WVPdHNq2TENQX5q9Beg=
For some reason the objective-c version only returns 24 bytes while the input is 28 bytes. I would expect it to be 32 bytes like in the .NET version. I was unable to determine what I'm doing wrong here.

Answer 1

The encryption error is:
kCCOptionPKCS7Padding & kCCModeCBC,
You need |, not & but kCCModeCBC is not a valid option and no option is needed because CBC is the default mode, you simply need:
kCCOptionPKCS7Padding,
Unfortunatly there are other objectiveC coding errors, mainly:
NSString* plainText = (const void *) [v_plainText UTF8String];
NSString *key = (const void *) [#"12345678ABCDEFGH!##$%^&*" UTF8String];
Instead use:
NSData* plainText = [v_plainText dataUsingEncoding:NSUTF8StringEncoding];
NSData *key = [#"12345678ABCDEFGH!##$%^&*" dataUsingEncoding:NSUTF8StringEncoding];
Here is the complete code converted to use NSData:
NSString* plainText = #"1234567890123456789012345678";
NSString* keyText = #"12345678ABCDEFGH!##$%^&*";
NSData* plainData = [plainText dataUsingEncoding:NSUTF8StringEncoding];
NSData *keyData = [keyText dataUsingEncoding:NSUTF8StringEncoding];
Byte iv[8] = {0,0,0,0,0,0,0,0};
size_t bufferSize = plainData.length + kCCBlockSize3DES;
NSMutableData *cypherData = [NSMutableData dataWithLength:bufferSize];
size_t movedBytes = 0;
CCCryptorStatus ccStatus;
ccStatus = CCCrypt(kCCEncrypt,
kCCAlgorithm3DES,
kCCOptionPKCS7Padding,
keyData.bytes,
kCCKeySize3DES,
iv,
plainData.bytes,
plainData.length,
cypherData.mutableBytes,
cypherData.length,
&movedBytes);
cypherData.length = movedBytes;
NSString* str = [cypherData base64EncodedStringWithOptions:0];
NSLog(#"str: %#", str);
Oputput:
str: geHFnvoept2aKiruo6InSvc7WVPdHNq2TENQX5q9Beg=