Threshold above which BLAKE3 hashing switches from single-thread
Hasher::update to multi-thread Hasher::update_rayon. The blake3
crate documents 128 KiB as the rule-of-thumb crossover on x86_64 —
below that the rayon thread-spawn overhead beats the per-byte
savings, so we always take the single-thread path. Per-packet
signing of normal NDN signed portions (a few hundred bytes to a
few KB) never reaches this threshold; bulk content publication
(multi-MB Data) does.
Signature type code for keyed BLAKE3. Analogous to
SignatureHmacWithSha256 (type 4) — requires a 32-byte shared secret;
provides both integrity and authentication of the source. Distinct
from the plain-digest code on purpose: see the plain-vs-keyed rationale
above. See SignatureBlake3Keyed in blake3-signature-spec.md.
Signature type code for plain BLAKE3 digest. Analogous to
DigestSha256 (type 0) — provides content integrity / self-certifying
names but no authentication. Anyone can produce a valid signature.
See DigestBlake3 in blake3-signature-spec.md.
Compute an unkeyed BLAKE3 hash, automatically dispatching to the
multi-thread update_rayon path when the input is large enough to
benefit. See BLAKE3_RAYON_THRESHOLD. Used by both
Blake3Signer (sign side) and Blake3DigestVerifier (verify
side) so that a single-call API “just gets faster” on large inputs
without callers needing to pick a code path.