CODEWITHSUNDEEP
iosencryptioncryptographyaes
OMGPOP
OMGPOP

Reputation: 952

iOS AES encryption wrong result

Here is how I encrypt the string: 

+ (NSString *)encrypt:(NSString *)message password:(NSString *)password {
    NSData *encryptedData = [[message dataUsingEncoding:NSUTF8StringEncoding] AES256EncryptedDataUsingKey:[password dataUsingEncoding:NSUTF8StringEncoding] error:nil];
  NSString *base64EncodedString = [NSString base64StringFromData:encryptedData length:[encryptedData length]];
  return base64EncodedString;
}

The plain text is:

{"roomID":"{\"array\":[\"949156\",\"949157\"]}","duration":15,"link":"","type":"text","thumbnailBlobID":"","posy":103.6809424405021,"text":"Aa","className":"Message","originalBlobID":"","datetime":"20140319214528457","selfDestructive":0,"userID":"949157","posx":1.347154229880634,"status":"normal","entityID":"20140319214528457and949157and{\"array\":[\"949156\",\"949157\"]}"}

This is what I get

gXqxfDhImRD7S20lUdYuCPAlXfqRnG6xk4w4K5Op/WnYMh6VgJUUqMifK2vHkUpAbnZ+wKdSWjfzU1PuOwvJ4dJ9EiHwjeyyorezFNG6eylYcOvMWNeU6+5Z9XxfcFngqhmxM6k1lf7bkttTu0FnEHad/czFgiMVTy60DJpFMLSODkKEVezqQB9s/f3Qy/B6+sF5Hs5E0FDn7kU6Jtm6mLkFjGzDCXTdFXNjdussbkTL8C1gcOnn4hrNkqQKb82MgqqYf8sVgs4FVIjsmoJd0ALY8y/5QbBkgc6ZyB4aOQPPx/u4HS3F7HXHkIkkAjZS/hiHQBRyfwCvi2uwFedno5twYogNW56pSMQqBeJBxBAhPMpXzb51853GLP4bCotGtOyEfU96x5kWHDOR5QA2WhYZkB3AALDJ2kfqzWR8iOKHo3zE6DCQ7aH0RwEFlNPi8vsNwvUqtQ7nUODA5lUMYah6W2rfDh/em8BD8dGF5J6IUTIlSerx8wWPA9bn/SxO

From website http://aesencryption.net (256 bit) (Which i assume to be the correct answer

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

Upvotes: 0

Views: 235

Answers (2)

nsdebug
nsdebug

Reputation: 364

Is it possible that the escape characters (the back slashes) are being interpreted differently in code versus via the web? The bottom line here is I would (in code) decode what you just encoded and you should come out with the same as what you put in. This is probably the test you want to conduct. Hope this helps. Also see comment below from @RobNapier

Upvotes: 0

Rob Napier
Rob Napier

Reputation: 299345

There is no single standard way to apply AES, or standard data format for the output. AES requires a number of helpers when used on data that is not exactly 16-bytes long, and they can be configured in different ways. I have no idea how the aesencryption.net tool is applying these helpers; it doesn't say. If AES256EncryptedDataUsingKey: is the particular piece of code I assume it, it applies them very poorly (it's very similar to the code I discuss in Properly Encrypting With AES With CommonCrypto). I would not be surprised if aesencryption.net does something different.

If you have a piece of plaintext and a key, and you pass it to an encryptor twice and get the same answer back, then your encryptor is broken. A correct AES encryptor (for almost any common use of AES) should always return different results for the same plaintext+key (otherwise an attacker can determine that two plaintexts are equal, which breaks the security proof of AES). In the most common case, this is achieved by having a unique initialization vector (IV). For password-based AES, you also include a random salt. So even if these were good implementations of AES, you wouldn't expect your results to match.

Upvotes: 1

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