Cannot use Aes256::new() because it neither accepts 'cipher::generic_array::GenericArray' nor 'generic_array::GenericArray'

[lordmulder]

Hello,

I started to get problems using Aes256::new() from aes crate recently.

Trying to use Aes256 with a key of type cipher::{generic_array::GenericArray like this:

use aes::Aes256;
use cipher::{generic_array::GenericArray, BlockEncrypt, KeyInit};

Aes256::new(GenericArray::from_slice(&full_key));

...now gives error:

error: use of deprecated struct `cipher::generic_array::GenericArray`: please upgrade to generic-array 1.x
  |
6 | use cipher::{generic_array::GenericArray, BlockEncrypt, KeyInit};
  |                             ^^^^^^^^^^^^
  |
  = note: `-D deprecated` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(deprecated)]`

(I use latest version of aes and cipher crates, i.e., v0.8.4 and v0.4.4, respectively)

---

However, if I try to follow your instruction "please upgrade to generic-array 1.x" by explicitly adding generic_array version 1.3.3 to the dependencies in Cargo.toml and using generic_array::GenericArray like this:

use aes::Aes256;
use cipher::{BlockEncrypt, KeyInit};
use generic_array::GenericArray;

Aes256::new(GenericArray::from_slice(&full_key));

...we get this error:

error[E0308]: mismatched types
    |
 40 |     let cipher = Aes256::new(GenericArray::from_slice(&full_key));
    |                  ----------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `&GenericArray<u8, UInt<..., ...>>`, found `&GenericArray<u8, _>`
    |                  |
    |                  arguments to this function are incorrect
    |
note: two different versions of crate `generic_array` are being used; two types coming from two different versions of the same crate are different types even if they look the same
   --> C:\Users\user\.cargo\registry\src\index.crates.io-1949cf8c6b5b557f\generic-array-1.3.3\src\lib.rs:470:1

What exactly am I supposed to do here? 😕

(And yes, I know that I could simply add an #[allow()] to ignore the depreciation warning, but that's not really nice 😟)

Thanks for any advice!
Regards.

[newpavlov]

It's a deprecation warning on the generic-array side, so you can simply ignore it, downgrade generic-array to v0.14.7, or ask them to remove the deprecation annotation.

We already migrated our crates to hybrid-array, but haven't released new versions yet.

[lordmulder]

I think forcing generic-array to v0.14.7 in my lib is not good, because other projects using my lib may be using generic-array too and will likely use the latest version of generic-array (currently v0.14.8), which results in build error due to conflicting version requirements - main application attempts to use, e.g., v0.14.8, but library requires old version v0.14.7 😥

Also, I can not simply ignore the warning, because I'm following the recommendation to build with -Dwarnings, so that warnings cause the build to fail.

Cluttering my code with #[allow(deprecated)] seems like the only "solution", but certainly not a nice one.

Regards.

[newpavlov]

I meant that you should execute cargo update -p generic-array --exact 0.14.7 to downgrade it in your Cargo.lock, not to use =0.14.7 in your Cargo.toml. Both 0.14.7 and 0.14.8 should be semver compatible, so you should be able to downgrade your application as well.

[JosiahParry]

@newpavlov, just want to make sure I'm following the issue—the next release of aes-gcm will migrate to a different dependency so the warning will go away but the from_slice() associate method will remain?

[newpavlov]

@JosiahParry
Yes, but note that from_slice is deprecated in favor of TryFrom.