peam-ssz

peam-ssz is a small, performance-focused SSZ encoding, decoding, and merkleization crate extracted from Peam, a Lean/Ethereum consensus client written in Rust.

The design goals are straightforward:

• keep dependencies minimal
• keep the hot path cheap
• stay close to Ethereum SSZ behavior

The crate depends only on sha2 for hashing. Everything else stays in-tree.

Warning: peam-ssz currently enables sha2's asm backend on aarch64, x86_64, and x86 builds to favor end-to-end throughput. The upstream sha2 documentation treats this as an application-level choice; we keep it enabled here deliberately.

Links

• Crate: crates.io/crates/peam-ssz
• API docs: docs.rs/peam-ssz
• Repository: malik672/Peam-ssz
• Upstream client: malik672/Peam

What It Includes

• core SSZ encode/decode traits and primitives
• fixed and variable-size collection helpers
• container utilities
• bitlist and bitvector support
• progressive SSZ helpers
• hash-tree-root and Merkle utilities

Repository layout:

• src/: crate implementation
• spec-tests/: Ethereum consensus spec-vector harness
• fuzz/: robustness and differential fuzzing targets
• benches/: Criterion differential benchmarks

Origins

This crate began as an extraction of Peam's internal SSZ code, which itself came from SigmaPrime ethssz, and was then shaped into a standalone library with tests, fuzzing, and benchmarks.

The original Peam sources were:

• Peam/src/ssz/mod.rs
• Peam/src/ssz/hash.rs

Validation

Run the crate test suite:

cargo test

Run the spec-test harness:

./spec-tests/download-vectors.sh
cargo test -p spec-tests -- --nocapture

The spec harness is wired to the Ethereum consensus spec vectors from v1.6.1.

Fuzzing

Fuzzing uses cargo-fuzz and libFuzzer.

Available targets:

• decode_robustness
• diff_header
• diff_list_u64

Run one target from the fuzz workspace:

cd fuzz
cargo fuzz run decode_robustness

Benchmarks

peam-ssz includes a differential Criterion benchmark harness that compares against:

• libssz
• Lighthouse SSZ (ethereum_ssz)
• ssz_rs

Run the benchmark suite:

cargo bench --bench peam_differential

The benchmark harness is intentionally narrow and focused on hot-path types such as primitives, fixed bytes, Vec<u64>, and a BeaconBlockHeader-shaped container. For current numbers, rerun the benches on your target machine rather than relying on committed local results.

Local benchmark snapshots are preserved in BENCHMARKS.md.