Coin Dance

Avalanche

 Bitcoin ABC

Allow miners to come to consensus on double spend transactions before they have been mined into a block (pre-consensus).

Bounded Looping Operations

 Independent

This proposal includes two new BCH virtual machine (VM) operations, OP_BEGIN and OP_UNTIL, which enable a variety of loop constructions in BCH contracts without increasing the processing or memory requirements of the VM.

Reduce on-chain fingerprintability of wallets

 Independent

Right now every wallet software does slightly different things with transaction preparation, which makes it possible for chain analysis to fingerprint transaction and detect which wallet is being used. It would be nice if at least we could have all P2PKH transactions look ‘the same’ so this isn’t possible.

Raise the 520 byte push limit & 201 op limit

 Independent

Updating this to match the MAX_SCRIPT_SIZE would effectively eliminate it as a roadblock to complex use cases, while still serving its purpose for DOS prevention.

Maxblocksize Based on Median Block Size

 Bitcoin Unlimited

The basic idea is that we look at recent block history. We calculate recent usage and use it to set a new limit that is much higher. We adjust every time a new block is found. With this the blocks are unlikely to ever go full, even at load peaks.

Zero-Knowledge Contingent Payments

 Bitcoin ABC | BCHD

Facilitate large scripts by moving them off-chain but tying them to a simple verify-only smart contract on-chain.

Fractional Satoshis

 Bitcoin ABC

Allow for denominations smaller than 1 satoshi.

Taproot

 Bitcoin ABC

Taproot is an interesting technology to enable multiparty privacy on a bitcoin.

Mandatory CashAddr for P2SH

 Electron Cash | Independent

Refuse sending BCH transactions to addresses starting with a 3.

Cash Intents

 Independent

Storage of human-meaningful transactional metadata on a per-transaction basis. Enriches the blockchain stored technical identifier with contextual information, such as who the sender is, what unit of account the sender was using, what exchange rate the sender used for calculating the technical amount and similar data.

Blocktorrent

 Independent

Blocktorrent is a method for breaking a block into small independently verifiable chunks for transmission, where each chunk is about one IP packet (a bit less than 1500 bytes) in size. In the same way that Bittorrent was faster than Napster, Blocktorrent should be faster than Xthin(ner).

Metadata Subtree

 Bitcoin ABC | Lokad SAS

Support for better, more detailed block-level metadata.

Merklix Trees

 Bitcoin ABC | Lokad SAS

Time Delay Penalty Based on Multiple Blocks

Prevent deep re-org attacks by penalizing alternate chaintips by a factor that is calculated by averaging the delays (in seconds) of each opposing block.

One Way Aggregate Signatures

 Electron Cash

A non-interactive fungibility solution for transactional privacy.

Improved 0-conf via security deposits

 Bitcoin Unlimited

the consumer will make a special ZCF transaction that pays the merchant and simultaneously posts a security deposit. If the transaction is honest, the consumer can later reclaim his deposit. If he tries to double spend, he necessarily reveals a second signature over the same public key which is then used by miners to claim his deposit for themselves. Pretty clever!

Graphene v2

 Bitcoin Unlimited

Introduce a set of improvements (phase 1) and extensions (phase 2) to improve both the performance and functionality of the Graphene block relay protocol.

Bobtail

 Bitcoin Unlimited

A Proof-of-Work Target that Minimizes Blockchain Mining Variance

Spedn

 Independent

A high level smart contracts language for Bitcoin Cash, designed for explicitness and safety.

Xthinner

 Independent

Improved xthin that leverages canonical transaction ordering.

OpenCAP alias protocol

 Independent

OpenCAP is a protocol that defines the standard by which cryptocurrency wallets can communicate with servers to relate aliases to cryptocurrency addresses.

The protocol allows for the decentralization of the alias -> address relationship.

CashDB

 Lokad SAS

CashDB delivers a specialized storage dedicated to the UTXO dataset of Bitcoin Cash. This component is intended to support livechain apps such as Bitcoin ABC or ElectrumX.

Bi-directional Overlay Network

 BCHD

A generic overlay network based on IPFS’s libp2p.

UTXO commitments

 Bitcoin ABC | bitCrust

The construction of a 32-byte hash that is uniquely defined for a UTXO set, that is, the set of all unspent transaction outputs that exist at a certain block in the blockchain

Restrict Transaction Versions

 Independent | Flowee

Transactions shall have as a version number of no other value than 1 or 2.
Blocks that have transactions which violate this rule shall be deemed invalid.

P2SH32

 Independent

Pay-to-Script-Hash-32 is a long-term solution for 80-bit P2SH collision attacks. It introduces a new address type for smart contracts that is cryptographically more secure.

Allow transactions <100 bytes (but >64)

 Independent

This rule prevents a hash griding attack, where SPV wallets can confuse a 64 byte transaction for a merkle node. The amount of entropy in each 32-byte sections of the transaction is insufficient to prevent a preimage attack. In this case, a valid transaction could be found with a hash equal to the first, or last, 32 bytes of a 64-byte transaction.

CashTokens

 Independent

CashTokens are a Bitcoin Cash virtual machine-enforced scheme for issuing, validating, and redeeming tokens. CashTokens enable on-chain token sales, transferable synthetic assets, decentralized exchanges, and prediction markets on Bitcoin Cash.

Support bigger integers

 Independent | General Protocols

Support integers larger than 32 bit for the purposes of improving the capability of smart contracts.

Previous discussion on this: https://youtu.be/XmH3A7Q0BJw?t=5400

Native Introspection Opcodes

 Independent | BCHN | General Protocols

This proposal adds a set of new virtual machine (VM) operations which enable BCH contracts to efficiently access details about the current transaction like output values, recipients, and more – without increasing transaction validation costs.

Bigger Script Integers

 Independent | BCHN | General Protocols

By expanding the upper bound of arithmetic inputs to 9223372036854775807, contracts can efficiently operate on values larger than the total possible satoshi value of any transaction output (approx. 2100000000000000). This enables contracts to manage balances of any size, clearing the way for large, public decentralized applications.

Adjust/Eliminate the 6-month Upgrade Schedule

 BCHN

Remove Child Pays for Parent

 Bitcoin Unlimited | Flowee | BCHN | General Protocols

Double spend proof creation and forwarding

 Bitcoin Unlimited | Independent | Flowee | BCHN

Update to inform other nodes of double spend attempts immediately to improve the reliability of 0-conf transactions.

Original implementation progress: https://gitlab.com/FloweeTheHub/thehub/merge_requests/10

https://gitlab.com/snippets/1883331

Support for Multiple OP_RETURNs

 Independent | BCHN

We propose to make presence of multiple OP_RETURN outputs qualify as standard transactions subject to the existing 223 byte limit for OP_RETURNs across all outputs of the transaction.

Remove the Chained Unconfirmed Tx Limit

 Bitcoin Unlimited | Flowee | BCHN | General Protocols

Safely increase or remove the 50 chained transaction limit.

ASERT Difficulty Adjustment Algorithm

 Bitcoin ABC | Independent | BCHN

Increase chained tx limit from 25 to 50

 Bitcoin ABC

Allows faster re-spending of unconfirmed transactions.

CashFusion

 Bitcoin ABC | BCHD | Electron Cash

Trustless, obfuscated coin consolidation. A complement to CashShuffle privacy/fungibility.

CashScript

 Independent | Bitcoin.com

A high level language enabling basic smart contract functionality on Bitcoin Cash.

SigChecks Overhaul

 Bitcoin ABC

Improved sigops counting.

OP_REVERSEBYTES

 Bitcoin ABC | Independent

OP_REVERSEBYTES reverses the bytes of the top stackitem.

MuSig

 BCHD

Added support for MuSig, a new way to handle signatures on Bitcoin.

Revised DAA

 Bitcoin ABC

Revise Difficulty Adjustment Algorithm

Electrs Electrum Server Integration

 Bitcoin Unlimited

Provide an alternative to the ElectrumX Electrum server by leveraging the more efficient Electrs Electrum server in Bitcoin Unlimited.

Enforce minimal pushdata for scriptSig

 Bitcoin ABC

As per existing standardness checks, enforce that all pushed data is a minimal representation at the script layer.

Enable Schnorr Signatures on OP_CHECKMULTISIG

 Bitcoin ABC

OP_CHECKMULTISIG and OP_CHECKMULTISIGVERIFY will be upgraded to accept Schnorr signatures in a way that is compatible with batch verification.

Scale to make 250MB blocks reliable

 Flowee

Original Satoshi codebase had lots of design decisions that limit the block size, like saving blocks in files of max 128MB. Memory usage was also spiking on large blocks and many other things.

Successfully tested 250MB block parallel validation on testnet.

TxId/AddressId & spendDB Indexer

 Flowee

This moves the txid indexer out of the full node which solves stability and maintenance problems. For instance you're node would go offline for some hours if you wanted to start a txid index.

Additionally add several other indexers with APIs of their own and each of which that can be enabled disabled separately.

CashID

 Independent

CashID is an open protocol that allows secure authentication based on the public key cryptography infrastructure that is currently present in the Bitcoin Cash ecosystem. Each user can prove to a service provider that they control a specific Bitcoin Cash address by signing a challenge request, as well as provide optional metadata.

Cash Accounts

 Independent

Cash Accounts is a naming system that can be used alongside regular bitcoin addresses and payment codes to simplify the process of sharing payment information.

Hash-DB

 Flowee

The Hash-DB is a database written specifically for the Bitcoin Cash UTXO set.
The goal is to get a massive multi-threading UTXO database optimized based on the behavior of blockchain.

The goal of 20.000 transactions per second has been safely reached.

CompactBlocks

 Bitcoin Unlimited

Supporting CB in BU would strengthen the connections between the BU peers and the rest of the network, without having to rely on intermediates.

SegWit Recovery Exception

 Bitcoin ABC

With the last protocol upgrade, the enforcement of the CLEANSTACK rule made it impossible to recover funds from Segwit transactions. With the upgrade, there will be an exception to this rule to enable recovery of these funds once again.

Enable Schnorr signatures

 Bitcoin ABC

Schnorr signatures are provably non-malleable and allow multiple parties to collaborate to produce a signature that is valid for the sum of their public keys. This is the building block for various higher-level constructions that improve efficiency and privacy.

Neutrino (BIP 157 & BIP 158)

 BCHD

Implemented as part of the Neutrino Wallet for Bitcoin Cash, Neutrino (BIP 157 & BIP 158) allows the creation of lightweight SPV wallets with strong network level privacy.

Restore OP Codes

 Bitcoin Unlimited | Bitcoin ABC

Re-activate the following additional opcodes: OP_MUL, OP_LSHIFT, OP_RSHIFT, and OP_INVERT.

CashShuffle

 Electron Cash

CashShuffle is a protocol for allowing users to combine their transactions with others, creating obfuscation. It builds upon CoinShuffle and adds a matching service. As such, it is a more complete and usable protocol.

Simple Ledger Protocol

 Electron Cash

Simple Ledger Protocol (SLP) uses the meta data in OP_RETURN for the issuance and transfer of tokens in conjunction with standard transaction outputs that each represent a number of token units specified by the sender.

Fast Sync via IPFS

 BCHD

Support faster syncing by downloading a previous UTXO set from IPFS.

Graphene v1

 Bitcoin Unlimited

An efficient method of announcing new blocks.

XVersionMessage

 Bitcoin Unlimited

BCH node extended version and configuration fields for transporting a generic key-value map that is meant to hold the configuration and version parameters to communicate capabilities with other nodes (such as transmission protocols like Graphene).

Clean Stack

 Bitcoin ABC

For a transaction to be valid, only a single non-zero item must remain on the stack upon completion of Script evaluation. If any extra data elements remain on the stack, the script evaluates to false. This is the same as BIP 62 rule #6.

Generalized version bits voting (BIP 135)

 Bitcoin Unlimited

BIP 135 extends the semantics of the signaling bits to cover arbitrary consensus changes, referred to under the general term 'forks'. The same range of version bits is used for signaling.

Default to 32MB blocks

 Bitcoin ABC

Start accepting blocks up to 32MB by default.

Re-enable Satoshi Opcodes

 Bitcoin ABC | nChain

Re-enable the previously disabled opcodes which were part of the original Bitcoin design. This should enable smart contract compilers, and a variety of functionality on Bitcoin Cash.

Increase default datacarriersize to 220 bytes

 Bitcoin ABC

To disincentivize the use of other methods to embed data into the chain, in particular via P2SH, the default datacarriersize is raised from 80 byte to 220 bytes, so it becomes the "cheapest" way of embedding data into the chain.