How to decrypt AES 256 https://aesencryption.net/ - IOS

Question

Plain text : Encrypt and decrypt text with AES algorithm

Key (256) : testsecret

Result (https://aesencryption.net/) : iFhSyFY3yYoO2G6GVGkdhZJjD+h0Pxv5fQnO3xIarzuGQSkIxlrpSprC5bC3gJ2U

i use small code in object to decrypt this this text :

(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; // char iv[kCCBlockSizeAES128 + 1]; bzero(iv, sizeof(iv)) ; CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES, 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 [NSMutableData dataWithBytesNoCopy:buffer length:numBytesDecrypted]; }

free(buffer); //free the buffer; return nil; }

Result : t\PFLFC\^X\^C^\^^\^RWQV\^\ypt text with AES algorithm

Seem it alway wrong first 16bit block. Can u help me. what i'm wrong when encrypt ?

Why the hell would you copy cryptographic code or test vectors from somebody that cannot even spell anything correctly and understands nothing about cryptography? Setting the blocksize of AES to 128, 192 or 256? Using a password instead of a key? What have they been drinking? Learn crypto first so you can at least distinguish between real and garbage like the code shown on that site. — Maarten Bodewes

Faysal Ahmed Faysal Ahmed · Accepted Answer · 2018-08-28T10:04:52

Try to use AESCrypt-ObjC instead of Cryptlib Library.

Installation

Add this line to your class:

#import "AESCrypt.h"

Usage

NSString *message = @"top secret message";
NSString *password = @"p4ssw0rd";

Encrypting

NSString *encryptedData = [AESCrypt encrypt:message password:password];

Decrypting

NSString *message = [AESCrypt decrypt:encryptedData password:password];

Hope this will help.

Also, you can see this answer: https://stackoverflow.com/a/51767050/5167909

How to decrypt AES 256 https://aesencryption.net/ - IOS

2 Answers