CHIPs
Cash Improvement Proposals: how BCH decides what goes into each May upgrade.
BCH has no foundation and no single client. A change ships when node teams, miners, exchanges and builders converge on a CHIP, usually debated for a year on bitcoincashresearch.org. See the upgrade timeline for what shipped when.
proposed
draft
- CHIP-2026-06 OP_SIGHASH Proposes an opcode that computes the transaction's signature hash and pushes it to the stack, without checking a signature. Verified
- CHIP-2026-06 Post-Quantum and Hybrid Signatures Proposes letting the existing signature opcodes verify more than one signature scheme, starting with post-quantum SPHINCS+ and hybrid secp256k1-plus-PQ keys, spendable from ordinary P2PKH outputs. Verified
- CHIP-2026-02 Simplified Header Verification (SHV) Proposes a Merkle Mountain Range commitment over block headers so light wallets can verify header history with a small, fixed-size state instead of downloading every header. Verified
- CHIP-2025-05 Native Elliptic Curve Arithmetic Operations Proposes OP_ECADD and OP_ECMUL for elliptic curve point addition and scalar multiplication in Script, aimed at zero-knowledge proofs and signature aggregation. Verified
- CHIP-2025-01 TXv5: Transaction Version 5 Proposes a version 5 transaction format with fractional satoshis, fractional CashTokens, detached signatures and smaller transactions. Verified
- CHIP-2021-07 UTXO Fastsync Proposes a way for nodes to create, share, check and load UTXO-set snapshots over the P2P network, so new nodes can sync in hours instead of replaying the whole chain. Verified
activated
- CHIP-2025-05 Bitwise: Re-Enable Bitwise Operations Enables OP_INVERT plus numeric and binary left/right shifts, completing Script's bitwise toolkit. Verified
- CHIP-2025-05 Functions: Function Definition and Invocation Operations Adds OP_DEFINE and OP_INVOKE, so contract bytecode can be split into reusable, immutable functions. Verified
- CHIP-2024-12 P2S: Pay to Script Makes bare Pay-to-Script outputs standard, raises NFT commitments from 40 to 128 bytes, and lifts the standard unlocking bytecode limit from 1,650 to 10,000 bytes. Verified
- CHIP-2024-07 BigInt: High-Precision Arithmetic for Bitcoin Cash Removes the script number length limit, so contracts can do arithmetic on numbers up to the 10,000-byte stack item size. Verified
- CHIP-2023-04 Adaptive Blocksize Limit Algorithm (ABLA) Replaces the fixed 32 MB block size limit with an algorithm that raises the limit as sustained demand grows, keeping 32 MB as the floor. Verified
- CHIP-2022-05 Pay-to-Script-Hash-32 (P2SH32) Adds a 32-byte-hash version of P2SH (OP_HASH256 <32 bytes> OP_EQUAL) to close off 80-bit collision attacks on contract addresses. Verified
- CHIP-2022-02 CashTokens: Token Primitives for Bitcoin Cash Adds fungible tokens and non-fungible tokens (NFTs) directly to Bitcoin Cash outputs, validated by consensus and readable by contracts. Verified
- CHIP-2021-05 Loops: Bounded Looping Operations Adds OP_BEGIN and OP_UNTIL, so contracts can loop, with every iteration charged by the VM cost limits. Verified
- CHIP-2021-05 VM Limits: Targeted Virtual Machine Limits Replaces the 201-opcode limit and 520-byte stack item limit with density-based operation-cost and hashing limits, and raises stack items to 10,000 bytes. Verified
- CHIP-2021-03-12 Multiple OP_RETURNs for Bitcoin Cash Made transactions with more than one OP_RETURN data output standard, keeping the 223-byte total limit. Verified
- CHIP-2021-03 Bigger Script Integers Expanded script numbers from 32-bit to 64-bit and re-enabled OP_MUL, with overflow-checked arithmetic. Verified
- CHIP-2021-02 Native Introspection Opcodes Added 14 opcodes that let contracts read the current transaction directly: input and output values, bytecode, counts, locktime and more. Verified
- CHIP-2021-01 Minimum Transaction Size (Allow Smaller Transactions) Lowered the minimum transaction size from 100 bytes to 65 bytes, still blocking the 64-byte Merkle-tree attack. Verified
- CHIP-2021-01 Restrict Transaction Version Made transaction versions other than 1 and 2 invalid by consensus, so a future transaction format can use a never-before-seen version number. Verified
- CHIP (unnumbered, 2021) Unconfirmed Transaction Chain Limit Removed the relay-policy limit of 50 chained unconfirmed transactions, so apps can send dependent payments without waiting for a block. Verified
superseded
withdrawn
- CHIP-2026-06 CashTokens FT+NFT Ambiguity Fix Proposed banning new outputs that hold both fungible tokens and a zero-byte immutable NFT, which contracts cannot tell apart from FT-only outputs. Retracted two days after publication. Verified
- CHIP-2021-01 PMv3: Version 3 Transaction Format A 2021 draft for a new transaction format to enable fixed-size inductive proofs for token covenants. Withdrawn in February 2022 in favour of CashTokens. Verified