Added versioning #35
Added versioning #35
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specs/casper_sharding_v2.1.md
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| @@ -455,7 +460,7 @@ For each one of these attestations: | |||
| * Let `attestation_indices` be `get_shards_and_committees_for_slot(crystallized_state, slot)[x]`, choosing `x` so that `attestation_indices.shard_id` equals the `shard_id` value provided to find the set of validators that is creating this attestation record. | |||
| * Verify that `len(attester_bitfield) == ceil_div8(len(attestation_indices))`, where `ceil_div8 = (x + 7) // 8`. Verify that bits `len(attestation_indices)....` and higher, if present (i.e. `len(attestation_indices)` is not a multiple of 8), are all zero | |||
| * Derive a group public key by adding the public keys of all of the attesters in `attestation_indices` for whom the corresponding bit in `attester_bitfield` (the ith bit is `(attester_bitfield[i // 8] >> (7 - (i %8))) % 2`) equals 1 | |||
| * Verify that `aggregate_sig` verifies using the group pubkey generated and `hash(slot.to_bytes(8, 'big') + parent_hashes + shard_id + shard_block_hash + justified_slot.to_bytes(8, 'big'))` as the message. | |||
| * Let `version = pre_fork_version if slot < fork_slot_number else post_fork_version`. Verify that `aggregate_sig` verifies using the group pubkey generated and `hash(slot.to_bytes(8, 'big') + parent_hashes + shard_id + shard_block_hash + justified_slot.to_bytes(8, 'big'))` as the message. | |||
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Need to add version to the msg
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@vbuterin There has been a discussion around defining the attestation message as an SSZ datastructure so we can remove any ambiguities in the generation of this message (big vs little endian, data type sizes, etc). I think this is a good idea. Thoughts? |
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Sounds good to me. |
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@paulhauner -- we are going with SSZ for serializing attestation signed data. Thanks for the suggestion |
specs/casper_sharding_v2.1.md
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| @@ -455,7 +474,8 @@ For each one of these attestations: | |||
| * Let `attestation_indices` be `get_shards_and_committees_for_slot(crystallized_state, slot)[x]`, choosing `x` so that `attestation_indices.shard_id` equals the `shard_id` value provided to find the set of validators that is creating this attestation record. | |||
| * Verify that `len(attester_bitfield) == ceil_div8(len(attestation_indices))`, where `ceil_div8 = (x + 7) // 8`. Verify that bits `len(attestation_indices)....` and higher, if present (i.e. `len(attestation_indices)` is not a multiple of 8), are all zero | |||
| * Derive a group public key by adding the public keys of all of the attesters in `attestation_indices` for whom the corresponding bit in `attester_bitfield` (the ith bit is `(attester_bitfield[i // 8] >> (7 - (i %8))) % 2`) equals 1 | |||
| * Verify that `aggregate_sig` verifies using the group pubkey generated and `hash(slot.to_bytes(8, 'big') + parent_hashes + shard_id + shard_block_hash + justified_slot.to_bytes(8, 'big'))` as the message. | |||
| * Let `version = pre_fork_version if slot < fork_slot_number else post_fork_version`. | |||
| * Verify that `aggregate_sig` verifies using the group pubkey generated and the serialized form of `AttestationSignedData(version, slot, parent_hashes, shard_id, shard_block_hash, crystallized_state.last_justified_slot)` as the message. | |||
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This should be attestation.justified_slot not crystallized_state.last_justified_slot. We've already checked to see that the attestation.justified_slot < crystallized_state.last_justified_slot so we are good to just pass in the attestation.justified_slot.
So we can just right justified_slot here
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One more correction @vbuterin |
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link: #5 |
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Should be |
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I wanted to reach out to you in an unconventional way. I'm a passionate programmer in the Consensys bootcamp and I want to learn the mathematical approach. How can a programmer escape the repetitive conditional statements of code to learn the complex computations that shape code?
Sincerely,
Carter
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