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0 pointsjre8y ago0 comments

Those are all very good points I didn't think about, thanks for these.

I'll fix the two bugs with verify_block and the possibility for a miner to inject invalid a output > input transaction.

I'll add a note for the 3 others.

0 comments

For deterministic serialization (~canonicalization), you can use sort_keys=True or serialize OrderedDicts. For deseialization, you'd need object_pairs_hook=collections.OrderedDict.

Most current blockchains sign a binary representation with fixed length fields. In terms of JSON, JSON-LD is for graphs and it can be canonicalized. Blockcerts and Chainpoint are JSON-LD specs:

> Blockcerts uses the Verifiable Claims MerkleProof2017 signature format, which is based on Chainpoint 2.0.

https://github.com/blockchain-certificates/cert-verifier-js/...

Cyph0n8y ago

FYI, dicts are now ordered by default as of Python 3.6.

cpburns20098y ago

That's an implementation detail, and shouldn't be relied upon. If you want an ordered dictionary, you should use collections.OrderedDict.

westurner8y ago

It's now the spec for 3.6+.

> #python news: @gvanrossum just pronounced that dicts are now guaranteed to retain insertion order. This is the end of a long journey.

https://twitter.com/raymondh/status/941709626545864704

More here: https://www.reddit.com/r/Python/comments/7jyluw/dict_knownor...

OrderedDicts are backwards-compatible and are guaranteed to maintain order after deletion.

Cyph0n8y ago

True, but if you need both key ordering and performance, dict is the better option.

j / k navigate · click thread line to collapse

0 comments

westurner8y ago

For deterministic serialization (~canonicalization), you can use sort_keys=True or serialize OrderedDicts. For deseialization, you'd need object_pairs_hook=collections.OrderedDict.

Most current blockchains sign a binary representation with fixed length fields. In terms of JSON, JSON-LD is for graphs and it can be canonicalized. Blockcerts and Chainpoint are JSON-LD specs:

> Blockcerts uses the Verifiable Claims MerkleProof2017 signature format, which is based on Chainpoint 2.0.

https://github.com/blockchain-certificates/cert-verifier-js/...

Cyph0n8y ago

FYI, dicts are now ordered by default as of Python 3.6.

cpburns20098y ago

That's an implementation detail, and shouldn't be relied upon. If you want an ordered dictionary, you should use collections.OrderedDict.

westurner8y ago

It's now the spec for 3.6+.

> #python news: @gvanrossum just pronounced that dicts are now guaranteed to retain insertion order. This is the end of a long journey.

https://twitter.com/raymondh/status/941709626545864704

More here: https://www.reddit.com/r/Python/comments/7jyluw/dict_knownor...

OrderedDicts are backwards-compatible and are guaranteed to maintain order after deletion.

Cyph0n8y ago

True, but if you need both key ordering and performance, dict is the better option.

j / k navigate · click thread line to collapse