RUSTSEC-2021-0061: 
Rust vulnerability analysis and mitigation

The vulnerability RUSTSEC-2021-0061 is related to the unification of multiple Rust crates (aes, aesni, aes-ctr, and aes-soft) into a single aes crate. This consolidation was implemented to improve the management of hardware-accelerated backends and simplify the codebase structure (RustCrypto PR).

The technical implementation involved combining four separate crates into a unified aes crate with optional features. The change included target-based gating of AES-NI vs AES-soft crate dependencies and added support for platform-specific optimizations. The modification required removing the deny(unsafe_code) directive from the toplevel to accommodate hardware-accelerated backends.

The consolidation affected projects using the individual crates (aesni and aes-soft) directly, requiring them to migrate to the unified aes crate. This change particularly impacted systems that were explicitly using AES-NI support or software implementations separately.

The solution involved migrating to the unified aes crate version 0.7.0 or later. The change was implemented with backward compatibility considerations, though projects directly depending on the individual crates needed to update their dependencies (RustCrypto PR).