Affected: RustCrypto AEADs

aes-gcm is a pure Rust implementation of the AES-GCM. Starting in version 0.10.0 and prior to version 0.10.3, in the AES GCM implementation of decrypt_in_place_detached, the decrypted ciphertext (i.e. the correct plaintext) is exposed even if tag verification fails. If a program using the `aes-gcm` crate's `decrypt_in_place*` APIs accesses the buffer after decryption failure, it will contain a decryption of an unauthenticated input. Depending on the specific nature of the program this may enable Chosen Ciphertext Attacks (CCAs) which can cause a catastrophic breakage of the cipher including full plaintext recovery. Version 0.10.3 contains a fix for this issue.

Affected: crates.io: aes-gcm

### Summary In the AES GCM implementation of decrypt_in_place_detached, the decrypted ciphertext (i.e. the correct plaintext) is exposed even if tag verification fails.

### Impact If a program using the `aes-gcm` crate's `decrypt_in_place*` APIs accesses the buffer after decryption failure, it will contain a decryption of an unauthenticated input. Depending on the specific nature of the program this may enable Chosen Ciphertext Attacks (CCAs) which can cause a catastrophic breakage of the cipher including full plaintext recovery.

### Details As seen in the implementation of [decrypt_in_place_detached](https://docs.rs/aes-gcm/latest/src/aes_gcm/lib.rs.html#309) for AES GCM, if the tag verification fails, an error is returned. Because the decryption of the ciphertext is done in place, the plaintext contents are now exposed via `buffer`.

This should ideally not be the case - as noted in page 17 of[ NIST's publication _Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC_](https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf): _In Step 8, the result of Step 7 is compared with the authentication tag that was received as an input: if they are identical, then the plaintext is returned; otherwise,FAIL is returned._

This is seems correctly addressed in the [AES GCM SIV implementation](https://docs.rs/aes-gcm-siv/latest/src/aes_gcm_siv/lib.rs.html#307), where the decrypted buffer is encrypted again before the error is r…