Key Length issue

[NTMS2017]

First I use my key (Len:50) and I get below error. Error state that key must be 128/192 or 256bits.
I am confuse here. You have 32 character and its works.

https://stackoverflow.com/questions/4850241/how-many-bits-in-a-character has a explain that it depends what is the character and what encoding it is in. So do you going to support ISO-8895-1 tp ISO-8895-9 as well as, UTF-8, UTF-16, UTF-32 encoding type?

I will stick to 32 length now. My local language is TR and ISO-8895-5 (Latin-5 (Turkish)). It will be good to cover all other language. Thanks

Unhandled exception:
Invalid argument(s): Key length must be 128/192/256 bits
#0 AESFastEngine.init (package:pointycastle/block/aes_fast.dart:66:7)
#1 AES.encrypt (package:encrypt/src/aes.dart:20:9)
#2 Encrypter.encrypt (package:encrypt/encrypt.dart:17:17)
#3 main (file:///Users/niyazitoros/IdeaProjects/github/untitled/bin/main.dart:11:35)
#4 _startIsolate. (dart:isolate-patch/dart:isolate/isolate_patch.dart:279)
#5 _RawReceivePortImpl._handleMessage (dart:isolate-patch/dart:isolate/isolate_patch.dart:165)

[leocavalcante]

Hi @NTMS2017
This is a constraint of the algorithm: https://en.wikipedia.org/wiki/Advanced_Encryption_Standard
Keys must be 128, 192 or 256 bits, exactly this sizes, it's not a range.

As you researched, 1 utf-8 char is 4 bytes, so a 32 char length key is equals to 32 * 4 = 128 bits.

So keys should have:

UTF-8 length	Bits
32	128
48	192
64	256

This can vary on the characters you are using

I highly recommend you to use a 256 bits key generated by a CSPRNG. PointyCastle has one, it is used for the Salts in password.

I will stick your issue to remember to add something like that in this project so you can generate cryptographic secure keys right from the terminal.

Note: You already able to do that thought /dev/urandom or RtlGenRandom.

[NTMS2017]

Thanks Leo, check all this tomorrow.