Protocol papers
Interoperability papers.
A bridge, a hub, or a shared protocol. The risk is usually the key or the committee that stands between the two chains, not the diagram.
How to read this shelf
Each card opens a study. The study is a reading of a public paper, not the paper and not a description of today's network. Status is a design paper unless the record says historical or failure case.
How to read this page
Research status is named on the page. Primary sources are linked. This is a mechanism and operating note, not investment suitability, legal advice, a security guarantee or an implementation certificate.
Polkadot · 2016 · Design paper
Polkadot: Vision for a heterogeneous multi-chain framework
Wood's 2016 vision paper: a relay chain that provides shared security and a queue of cross-chain messages, with parachains that keep their own state transition. It is a vision paper. The live protocol has a specification of its own.
Cosmos · 2016 · Design paper
Cosmos: A Network of Distributed Ledgers
The Cosmos paper: independent zones running a BFT consensus, connected by a hub, speaking a packet protocol that later became IBC. Unlike Polkadot's shared-security vision, zones here are sovereign. They choose their own validator sets.
Atomic swaps · 2018 · Design paper
Atomic Cross-Chain Swaps
A swap across ledgers where either every transfer completes or none does, using hash locks and time locks. There is no custodian in the paper. A party can still walk away and leave the other waiting.
Sprites · 2017 · Design paper
Sprites and State Channels
State channels whose disputes do not have to hop one channel at a time. A global preimage manager lets a payment resolve in constant time on-chain. Lightning did not adopt this design as its production path.
IBC · 2020 · Design paper
The Interblockchain Communication Protocol
Two chains verify each other with light clients. A relayer carries packets and proofs. The relayer is not trusted to tell the truth. It is trusted to bother showing up. Security is the security of both chains.
Payment channels · 2013 · Design paper
Bitcoin Payment Channels
Two parties lock coins in a shared output and exchange updated transactions that are not broadcast. Only the last state, or a dispute, hits the chain.
Eltoo · 2018 · Design paper
eltoo: A Simplified Update Mechanism for Lightning
Eltoo replaces penalties with a sequence of state numbers. A later state can spend an earlier one. Nothing is confiscated. The latest number wins if it is published in time.
Channel factories · 2018 · Design paper
Scalable Funding of Bitcoin Micropayment Channel Networks
A factory is a shared on-chain output that several parties can use to allocate many channels off-chain, so the chain sees the factory and not every channel.
BIP 68 · 2015 · Design paper
Relative lock-time using consensus-enforced sequence numbers
BIP 68, Relative lock-time using consensus-enforced sequence numbers. Relative lock-time (RLT) consensus-enforced semantics of the sequence number field to enable a signed transaction input to remain invalid for a defined period of time after confirmation of its corresponding outpoint.
BIP 347 · 2023 · Design paper
OP_CAT in Tapscript
BIP 347, OP_CAT in Tapscript. OP_CAT as a tapscript opcode which allows the concatenation of two values on the stack.
EIP 152 · 2016 · Design paper
Add BLAKE2 compression function `F` precompile
EIP 152, Add BLAKE2 compression function `F` precompile. This EIP will enable the BLAKE2b hash function and other higher-round 64-bit BLAKE2 variants to run cheaply on the EVM, allowing easier interoperability between Ethereum and Zcash as well as other Equihash-based PoW coins.
EIP 4788 · 2022 · Design paper
Beacon block root in the EVM
EIP 4788, Beacon block root in the EVM. Commit to the hash tree root of each beacon chain block in the corresponding execution payload header.
ERC 1328 · 2018 · Design paper
WalletConnect URI Format
ERC 1328, WalletConnect URI Format. This standard defines how the data to connect some application and a wallet can be encoded with a URI.
ERC 7786 · 2024 · Design paper
Cross-Chain Messaging Gateway
ERC 7786, Cross-Chain Messaging Gateway. This proposal describes an interface, and the corresponding workflow, for smart contracts to send arbitrary data through cross-chain messaging protocols.
ERC 7943 · 2025 · Design paper
uRWA - Universal Real World Asset Interface
ERC 7943, uRWA - Universal Real World Asset Interface. The Universal RWA (uRWA) standard, a set of interfaces for tokenized Real World Assets (RWAs) such as securities, real estate, commodities, or other physical/financial assets on the blockchain.
BIP 197 · 2019 · Design paper
Hashed Time-Locked Collateral Contract
BIP 197, Hashed Time-Locked Collateral Contract. A script for generalized debt agreement contract based on Hashed Time-Lock Contract (BIP 199) transactions according to the Atomic Loans specification (https://arxiv.org/pdf/1901.05117.pdf).
BIP 300 · 2017 · Design paper
Hashrate Escrows (Consensus layer)
BIP 300, Hashrate Escrows (Consensus layer). BIP-300 enables a new type of L2, where "withdrawals" (the L2-to-L1 txns) are governed by proof-of-work -- instead of a federation or fixed set of pubkeys.
BIP 326 · 2021 · Design paper
Anti-fee-sniping in taproot transactions
BIP 326, Anti-fee-sniping in taproot transactions. This document proposes a certain type of wallet behaviour which uses BIP341 taproot[1].
LayerZero · 2024 · Design paper
LayerZero v2: endpoint, message libraries, and decentralised verifier networks
LayerZero v2 splits an endpoint that applications call from the message libraries and verifier sets that actually attest a remote event.
Wormhole · 2021 · Design paper
Wormhole: guardian-attested generic message passing
Wormhole publishes generic messages attested by a guardian set. The guardian quorum, not a light client of the source chain, is the trust assumption in the base design.
Axelar · 2021 · Design paper
Axelar: cross-chain messages verified by its validator set
Axelar publishes cross-chain delivery verified by Axelar's own validator set, which runs a consensus the destination application is asked to trust.
Hyperlane · 2023 · Design paper
Hyperlane: modular interchain security
Hyperlane publishes message passing where the application picks an interchain security module, instead of inheriting one unnamed verifier.
Circle CCTP · 2023 · Design paper
Cross-Chain Transfer Protocol: native burn and mint for USDC
CCTP burns USDC on a source chain and mints USDC on a destination chain when Circle's attestation service signs the burn. The attestation is the trust assumption.
Chainlink CCIP · 2023 · Design paper
Cross-Chain Interoperability Protocol
CCIP publishes cross-chain messages and token movements verified by Chainlink's specified risk-management and committing sets, not by the 2017 oracle white paper alone.
Across Protocol · 2022 · Design paper
Across: intents settled by a relayer and a settlement contract
Across publishes an intent: a user names a destination fill, a relayer fills it, and a settlement contract later reimburses the relayer if the origin deposit checks out.
Hop Protocol · 2021 · Design paper
Hop: transfer bonds and an AMM between rollup representations
Hop publishes a transfer that mints a hop token against a bonded rollup exit, then swaps that representation through an AMM so a user does not wait out the rollup's full exit.
Babylon · 2024 · Design paper
Babylon: Bitcoin staking as a timestamp and slashable bond
Babylon publishes a way to lock bitcoin in a Bitcoin script and use that lock as a bond for another network, with slashing expressed as a Bitcoin transaction rather than as a wrapped token.
Botanix · 2024 · Design paper
Spiderchain: an EVM chain pegged by a rotating set of Bitcoin multisigs
Botanix publishes an EVM chain whose bitcoin peg is held by a rotating set of multisignature wallets, the spiderchain, rather than by a validity proof in Bitcoin script.
XCM · 2022 · Design paper
Cross-Consensus Messaging: Polkadot's message format
XCM is a message format between consensus systems in the Polkadot line. It is not a bridge to Ethereum, and it is not the Polkadot white paper's security argument restated.
Chainflip · 2023 · Design paper
Chainflip: a threshold-custody cross-chain AMM
Chainflip publishes an AMM whose inventories are native assets on their own chains, held by a threshold of validators, rather than wrapped tokens on one ledger.
Threshold tBTC · 2020 · Design paper
tBTC: bitcoin custody by a signer set with a redemption flow
tBTC publishes a redemption path from a token back to bitcoin, with custody held by a signer set, rather than by a single custodian's published IOU.
Connext · 2021 · Design paper
Connext Amarok: modular cross-chain transfers
Connext publishes cross-chain transfers where liquidity is fronted on the destination and repaid when the origin message is authenticated by the messaging layer the docs select.
Stargate · 2022 · Design paper
Stargate: unified liquidity pools for cross-chain transfers
Stargate publishes pools of a shared asset on several chains, so a transfer debits one pool and credits another, with a messaging layer underneath.
Noble chain · 2023 · Design paper
Noble: an issuance chain for native assets in the Cosmos line
Noble publishes a chain whose role is to issue native assets, such as a Circle-related USDC, into the IBC network, so the asset is minted there rather than wrapped by an unnamed bridge.
ERC 5164 · 2022 · Design paper
Cross-Chain Execution
A desk note on ERC 5164 (Cross-Chain Execution). The file's status is Last Call. The note records the text. It does not measure who runs it.
ERC 5559 · 2022 · Design paper
Cross Chain Write Deferral Protocol
A desk note on ERC 5559 (Cross Chain Write Deferral Protocol). The file's status is Stagnant. The note records the text. It does not measure who runs it.
ERC 6170 · 2022 · Design paper
Cross-Chain Messaging Interface
A desk note on ERC 6170 (Cross-Chain Messaging Interface). The file's status is Draft. The note records the text. It does not measure who runs it.
ERC 6358 · 2023 · Design paper
Cross-Chain Token States Synchronization
A desk note on ERC 6358 (Cross-Chain Token States Synchronization). The file's status is Review. The note records the text. It does not measure who runs it.
ERC 7683 · 2024 · Design paper
Cross Chain Intents
A desk note on ERC 7683 (Cross Chain Intents). The file's status is Draft. The note records the text. It does not measure who runs it.
ERC 7700 · 2024 · Design paper
Cross-chain Storage Router Protocol
A desk note on ERC 7700 (Cross-chain Storage Router Protocol). The file's status is Draft. The note records the text. It does not measure who runs it.
ERC 7802 · 2024 · Design paper
Token With Mint/Burn Access Across Chains
A desk note on ERC 7802 (Token With Mint/Burn Access Across Chains). The file's status is Draft. The note records the text. It does not measure who runs it.
ERC 7841 · 2024 · Design paper
Cross-chain Message Format and Mailbox
A desk note on ERC 7841 (Cross-chain Message Format and Mailbox). The file's status is Draft. The note records the text. It does not measure who runs it.
ERC 8121 · 2025 · Design paper
Cross-Chain Function Calls via Hooks
A desk note on ERC 8121 (Cross-Chain Function Calls via Hooks). The file's status is Draft. The note records the text. It does not measure who runs it.