# GHSA-jp3w-3q88-34cf: Miscomputation when performing AES encryption in rust-crypto

> Incorrect AES key expansion causes inconsistent encryption results, potentially leading to data integrity issues or failed decryption in applications using rust-crypto.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 28 Feb 2022
- **Also known as:** RUSTSEC-2022-0011

## What is GHSA-jp3w-3q88-34cf?

GHSA-jp3w-3q88-34cf is a vulnerability in rust-crypto, published on 28 Feb 2022. 

### Official description

The following Rust program demonstrates some strangeness in AES encryption - if you have an immutable key slice and then operate on that slice, you get different encryption output than if you operate on a copy of that key.

For these functions, we expect that extending a 16 byte key to a 32 byte key by repeating it gives the same encrypted data, because the underlying rust-crypto functions repeat key data up to the necessary key size for the cipher.

```rust
use crypto::{
    aes, blockmodes, buffer,
    buffer::{BufferResult, ReadBuffer, WriteBuffer},
    symmetriccipher,
};

fn encrypt(
    key: &[u8],
    iv: &[u8],
    data: &str,
) -> Result<String, symmetriccipher::SymmetricCipherError> {
    let mut encryptor =
        aes::cbc_encryptor(aes::KeySize::KeySize256, key, iv, blockmodes::PkcsPadding);

    let mut encrypted_data = Vec::<u8>::new();
    let mut read_buffer = buffer::RefReadBuffer::new(data.as_bytes());
    let mut buffer = [0; 4096];
    let mut write_buffer = buffer::RefWriteBuffer::new(&mut buffer);

    loop {
        let result = encryptor.encrypt(&mut read_buffer, &mut write_buffer, true)?;

        encrypted_data.extend(
            write_buffer
                .take_read_buffer()
                .take_remaining()
                .iter()
                .copied(),
        );

        match result {
            BufferResult::BufferUnderflow => break,
            BufferResult::BufferOverflow => {}
        }
    }

    Ok(hex::encode(encrypted_data))
}

fn working() {
    let data = "data";
    let iv = [
        0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE,
        0xFF,
    ];
    let key = [
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
        0x0F,
    ];
    // The copy here makes the code work.
    let key_copy = key;
    let key2: Vec<u8> = key_copy.iter().cycle().take(32).copied().collect();
    println!("key1:{} key2: {}", hex::encode(&key), hex::encode(&key2));

    let x1 = encrypt(&key, &iv, data).unwrap();
    println!("X1: {}", x1);

    let x2 = encrypt(&key2, &iv, data).unwrap();
    println!("X2: {}", x2);

    assert_eq!(x1, x2);
}

fn broken() {
    let data = "data";
    let iv = [
        0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE,
        0xFF,
    ];
    let key = [
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
        0x0F,
    ];
    // This operation shouldn't affect the contents of key at all.
    let key2: Vec<u8> = key.iter().cycle().take(32).copied().collect();
    println!("key1:{} key2: {}", hex::encode(&key), hex::encode(&key2));

    let x1 = encrypt(&key, &iv, data).unwrap();
    println!("X1: {}", x1);

    let x2 = encrypt(&key2, &iv, data).unwrap();
    println!("X2: {}", x2);

    assert_eq!(x1, x2);
}

fn main() {
    working();
    broken();
}
```

The output from this program:

```shell
     Running `target/host/debug/rust-crypto-test`
key1:000102030405060708090a0b0c0d0e0f key2: 000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f
X1: 90462bbe32965c8e7ea0addbbed4cddb
X2: 90462bbe32965c8e7ea0addbbed4cddb
key1:000102030405060708090a0b0c0d0e0f key2: 000102030405060708090a0b0c0d0e0f000102030405060708090a0b0c0d0e0f
X1: 26e847e5e7df1947bf82a650548a7d5b
X2: 90462bbe32965c8e7ea0addbbed4cddb
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `"26e847e5e7df1947bf82a650548a7d5b"`,
 right: `"90462bbe32965c8e7ea0addbbed4cddb"`', src/main.rs:83:5
```

Notably, the X1 key in the `broken()` test changes every time after rerunning the program.

## Which versions are affected by GHSA-jp3w-3q88-34cf?

3 open source packages ship an affected version, including rust-crypto.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rust-crypto` | crates.io | All versions to 0.2.36 | None |
| `rust-crypto` | crates.io | All versions to 0.2.36 | None |
| `rust-crypto` | crates.io | From 0.0.0-0 | None |

## How do I fix GHSA-jp3w-3q88-34cf?

No fix has been published for GHSA-jp3w-3q88-34cf yet. Limit exposure of the affected software until one is available.

## Is GHSA-jp3w-3q88-34cf being exploited?

There is no known exploitation of GHSA-jp3w-3q88-34cf in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-jp3w-3q88-34cf and fix it if it is affected.

What it is: GHSA-jp3w-3q88-34cf is a vulnerability in rust-crypto, published on 28 Feb 2022. 
Exploitation: There is no known exploitation of GHSA-jp3w-3q88-34cf in the wild and no public exploit code.

Affected packages and fixed versions:
- rust-crypto (crates.io): affected all versions up to 0.2.36; no fix listed
- rust-crypto (crates.io): affected all versions up to 0.2.36; no fix listed
- rust-crypto (crates.io): affected from 0.0.0-0; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/GHSA-jp3w-3q88-34cf/ (Markdown: https://insights.sbomify.com/GHSA-jp3w-3q88-34cf/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-jp3w-3q88-34cf

---
From sbomify Insights: https://insights.sbomify.com/GHSA-jp3w-3q88-34cf/
Summaries are generated and may contain mistakes; the official description above is the record.