Way More Scalable than on Ethereum — ZK-Rollup is considered as the holy grail of Ethereum Layer 2 scaling solution. In general, my own view is that in the short term, optimistic rollups are likely to win out for general-purpose EVM computation and ZK rollups are likely to win out for simple payments, exchange and other application-specific…

Run Zcash on Bitcoin — Previously, we have proved one knows some mathematical secret using zero knowledge proof (ZKP), without revealing the secret itself. The secret knowledge include: a private key corresponding to a public key in ZK puzzles a hash preimage to a public digest in ZK key-statement proof a ciphertext is the encryption…

Pairing-based Cryptography: Part 2 — Boneh-Lynn-Shacham (BLS) is a signature scheme based on bilinear pairings. Compared to ECDSA or Schnorr signatures, it enjoys several salient advantages: 2 times shorter friendly to signature and key aggregation deterministic: it does not rely on random number generators. Due to its minimal storage and bandwidth requirements, it has been…

Run Ethereum Smart Contracts on Bitcoin — Why is it needed? sCrypt is Bitcoin’s native smart contract language. Ideally, everyone shall just develop smart contracts in sCrypt, leveraging the most scalable blockchain. In practice, we also understand that many projects and developers have invested plenty of time and money into developing their current Solidity codebases. The transpiler facilitates developers to migrate…

Pairing-based Cryptography: Part 1 — Pairing-based cryptography is a variant of elliptic curve cryptography, which Bitcoin ECDSA signatures are based on. Thanks to the characteristics of pairing, new cryptographic algorithms and protocols can achieve functions or efficiency which cannot be realized otherwise, such as identity-based encryption (IBE), attribute-based encryption (ABE), authenticated key exchange (AKE), and…

Run Monero on Bitcoin — We have implemented the first-ever Ring Signature in Bitcoin. Ring Signatures A ring signature is a type of digital signature that allows a message to be signed by a single member in a group, or a ring. It proves that someone in the ring indeed signs, but there is no way to…

Upgrade Bitcoin’s Elliptic Curve Without a Fork and More This is the third instalment of our collaboration with nChain. We would like to give special thanks to Dr Enrique Larraia for authoring the whitepaper this article is based on and helping guide the implementation. A standard payment transaction can be…

By Programming It in a Smart Contract — We develop a novel approach to emulate any SIGHASH flag, by simply coding the logic in a smart contract. It requires no protocol change and is thus much more practical and flexible than adding a hardcoded flag through a fork, every time a new use case is conceived. SIGHASH Flags A SIGHASH…