Add compressed lamport pubkey fingerprint#78
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danielemiliogarcia wants to merge 13 commits intodevfrom
Open
Add compressed lamport pubkey fingerprint#78danielemiliogarcia wants to merge 13 commits intodevfrom
danielemiliogarcia wants to merge 13 commits intodevfrom
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| println!( | ||
| "\nSerialized compressed Lamport public key ({} bytes)", | ||
| serialized_compressed.len() | ||
| ); | ||
| println!( | ||
| "Serialized uncompressed Lamport public key ({} bytes)", | ||
| serialized_uncompressed.len() | ||
| ); |
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Serialized compressed Lamport public key (51 bytes)
Serialized uncompressed Lamport public key (20515 bytes)
examples/sign_verify_lamport.rs
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| // Difference in size between serialized compressed and uncompressed public key | ||
| println!( | ||
| "\nSerialized compressed Lamport public key ({} bytes)", | ||
| bincode::serialize(&lamport_pubkey.to_compressed()).unwrap().len() | ||
| ); | ||
| println!( | ||
| "Serialized uncompressed Lamport public key ({} bytes)", | ||
| bincode::serialize(&lamport_pubkey).unwrap().len() | ||
| ); | ||
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Even at 1 bit level (as used for garbled circuits wire labels values) the compression reduces the key > 2x
Serialized compressed Lamport public key (51 bytes)
Serialized uncompressed Lamport public key (115 bytes)
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Add compressed lamport pubkey fingerprint
This PR introduces a compressed representation of
LamportPublicKeyto reduce storage and transmission size, along with a matching expansion API that re-derives or reloads the full key and verifies integrity via BLAKE3.Motivation
A Lamport public key grows linearly with the message bit length: a key for a 256-bit message already serialises to several kilobytes. Storing or passing the full key around adds unnecessary overhead. This PR addresses that by separating the identity of a key (its BLAKE3 fingerprint + metadata) from its full material.
Example size comparison (from the updated example output):
The ratio grows with
message_bit_length.Changes
New type -
LamportCompressedPubKeyLamportPublicKey::to_compressed()and theFrom<&LamportPublicKey>impl construct it automatically.verify_against(&LamportPublicKey)checks that a re-derived key still matches the stored fingerprint.New trait -
LamportPubKeyIdImplemented by both
LamportPublicKey(computes on the fly) andLamportCompressedPubKey(returns storedid). Used to unify operations.New function -
KeyManager::expand_lamport()Reconstructs the full
LamportPublicKeyAfter reconstruction, the BLAKE3 fingerprint is verified against the stored
idTests
Unit tests have been added