Hashing contract

Hashing in Strata is not an optimization. It is a formal contract.

If two systems compute different hashes for the same logical value, at least one of them is incorrect.

There is no acceptable deviation.

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What is hashed

Strata hashes are computed over canonical Strata Core Binary (.scb) bytes only.

Not over:

• Strata Text

• decoded in-memory structures

• transport envelopes

• framing metadata

• file headers

• runtime-specific representations

Only canonical .scb bytes are valid hash input.

If it is not canonical, it is not hashable.

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Hash function

Strata uses BLAKE3-256.

Properties required by the system:

• deterministic

• fast

• cryptographically secure

• identical across platforms

• stable over time

The hash output is exactly 32 bytes.

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Hash determinism

Hash determinism is guaranteed by construction.

Because:

• canonical encoding is unique

• encoding rules are frozen per version

• all implementations encode identically

The following always holds:

Same logical value -> same canonical bytes -> same hash

This is a hard invariant.

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Hash computation order

Hashing always occurs after canonical encoding.

hash = BLAKE3(canonical_scb_bytes)

There is no alternative order. There is no shortcut. There is no pre-hashing.

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No normalization before hashing

Strata forbids any transformation before hashing.

The following are explicitly forbidden:

• map reordering

• whitespace trimming

• integer normalization

• UTF-8 repair

• trailing byte removal

• schema-driven coercion

If input is non-canonical, hashing must not proceed.

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Hash stability across languages

All implementations must produce:

• identical canonical bytes

• identical hash output

for the same logical value.

Language choice is irrelevant. Runtime choice is irrelevant. Platform choice is irrelevant.

If two languages disagree, one implementation is wrong.

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Hash stability across time

Once a Strata version is finalized:

• canonical encoding is frozen

• hash semantics are frozen

Hashes produced today must match hashes produced in the future for the same value under the same version.

This is not a goal. It is a requirement.

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Version boundaries

If a change would alter:

• canonical bytes

• hash input

• hash output

it requires:

• a new minor version

• a new Northstar

• explicit documentation

Hash changes are never silent.

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Security implications

This hashing contract enables:

• content-addressed storage

• tamper detection

• digital signatures

• reproducible builds

• distributed consensus

• audit-grade verification

Any deviation breaks these guarantees.

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What Strata does not do

Strata hashing does not:

• include transport metadata

• support multiple hash algorithms

• allow runtime configuration

• attempt backward-compatible hashing

• accept non-canonical input

Simplicity is part of the safety model.

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Summary

• hashes are computed over canonical .scb bytes only

• BLAKE3-256 is mandatory

• encoding precedes hashing

• non-canonical data is not hashable

• hashes are stable across languages and time

• breaking the contract requires a new version

In Strata, hashes are law.