Domain separation
Truestamp's rule that every hash over its own evidence is SHA-256 computed over a reserved single-byte prefix plus the data (RFC 6962 style), so a hash made for one purpose (Merkle leaf, node, item claims, proof payload) can never collide with or be replayed as a hash for another purpose.
Overview
Domain separation is the rule that every hash Truestamp computes over its own evidence is SHA-256 over a distinct reserved single-byte prefix followed by the data, the approach standardized by RFC 6962. Because the prefix differs per context, a hash computed for one purpose (a Merkle leaf, an internal node, an item’s claims, the proof signing payload) can never collide with or be replayed as a hash for another purpose, even when the underlying bytes are identical. The reserved byte for each context is called a byte prefix, and every reserved value is listed in the byte-prefix registry. The full rationale, the attacks it blocks, and cross-language reproduction examples are in domain-separated hashing.
Citations
- RFC 6962: Certificate Transparency. Source of the byte-prefix domain-separation approach, including the
0x00leaf and0x01node prefixes.