From segment bytes to an optional signed root

This figure documents the historical i386 source baseline. Current native x86-64/AArch64 qualification is recorded separately; this is not an ELF64 or native SMP implementation diagram.

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From segment bytes to an optional signed root A segment contains its header, compact events and a footer with sizes, checksum, prior checksum and flags. Compact events retain a payload digest rather than full payload bytes. Versioned BLAKE2s hashes feed a Merkle epoch root; explicit signing adds an Ed25519 signature. Segment writing precedes hash/root sidecars, with removal on sidecar failure. A signature is not automatic or a claim of overall correctness. segment:events->hashes canonical event summaries hashes->root Merkle construction root->signature explicit signing segment Segment file · ordered record layout header event count + ID / clock range compact events metadata + parents + payload digest / schema commit footer sizes, checksum, prior segment checksum, flags hashes Hash sidecar versioned BLAKE2s event hashes root Epoch-root sidecar Merkle root signature Optional Ed25519 signature signed root, not blanket correctness write Write segment → hash/root sidecars sidecar failure removes incomplete segment
From segment bytes to an optional signed root A segment contains its header, compact events and a footer with sizes, checksum, prior checksum and flags. Compact events retain a payload digest rather than full payload bytes. Versioned BLAKE2s hashes feed a Merkle epoch root; explicit signing adds an Ed25519 signature. Segment writing precedes hash/root sidecars, with removal on sidecar failure. A signature is not automatic or a claim of overall correctness. segment->hashes canonical event summaries hashes->root Merkle construction root->signature explicit signing segment Segment file Header: count, ranges Events: parents, schema, payload digest Footer: sizes, checksum, prior checksum, flags hashes Hash sidecar versioned BLAKE2s event hashes root Epoch-root sidecar Merkle root signature Optional Ed25519 signature signed root, not blanket correctness write Write segment → hash/root sidecars sidecar failure removes incomplete segment

Checksums, canonical event hashes, Merkle roots and signatures protect different layers.

Text equivalent and source references
  • A segment contains its header, compact events and a footer with sizes, checksum, prior checksum and flags. Compact events retain a payload digest rather than full payload bytes.
  • Versioned BLAKE2s hashes feed a Merkle epoch root; explicit signing adds an Ed25519 signature. Segment writing precedes hash/root sidecars, with removal on sidecar failure. A signature is not automatic or a claim of overall correctness.

Record / dependency map. Source paths refer to the atlas baseline; the kernel checkout is private.

  • kernel/graph/cjournal.c · write_segment, write_segment_hashes, cjournal_sign_segment
  • include/cjournal.h · cjournal_event_t
  • kernel/graph/causal.c · causal_event_hash_with_payload_hash

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