Did Taproot Enable All Bitcoin Scripts? A Dev’s Learning Journey

Pre-Taproot:

• Bitcoin supported basic, reliable scripts:

  • P2PKH (Pay-to-PubKey-Hash): Standard “send to address”—locked to public key hash.

  • P2SH (Pay-to-Script-Hash): Allowed multi-sig, simple smart contracts, via locking to a script hash.

• Scripting was intentionally limited. No loops, no stateful contracts—just straightforward unlocking of coins by proving ownership or satisfying simple conditions.

• Complex contracts? Possible, but with privacy and scalability tradeoffs (scripts had to be revealed fully when spending, and couldn’t enforce future spend rules).

Post-Taproot:

• Existing scripts (P2PKH, P2SH) are untouched—they still work.

• What’s new:

  • Taproot (P2TR) outputs: Funds can be spent either by single-sig or by revealing one “branch” from a Merkle tree of scripts.

  • Schnorr signatures: Enables aggregated (batch) signatures, better privacy, and lower fees for advanced contracts.

  • MAST (Merkelized Abstract Syntax Trees): Multiple spending conditions—only the used one is revealed, others stay hidden.

  • Tapscript: Upgraded scripting language for Taproot, paving the way for future extensibility and better smart contracts.

In short:
Taproot didn’t “enable all scripts,” but it added a new advanced toolkit (P2TR, Schnorr, MAST, Tapscript) for powerful, private, and efficient contracts—right alongside legacy outputs.

How Do the New Taproot Features Actually Work?

1. Schnorr Signatures

• Technical: Can aggregate multiple signatures into one using math only possible with Schnorr—not ECDSA.

• Simple Example:

  • Before: 3-of-5 multi-sig meant 3 separate sigs exposed on-chain.

  • Now: 3 signatures become one, undistinguishable from single-sig spends.

• Real benefit: Cheaper, faster, and fully private multi-party transactions.

2. MAST (Merkelized Abstract Syntax Trees)

• Technical: Store multiple possible scripts as leaves in a Merkle tree, commit only to the root in the output.

• Simple Example:

  • Lock BTC so “Alice can spend anytime OR Bob+Charlie after 3 months.”

  • When spent, only reveal the script used (“branch”), not the unused paths.

• Result: Smarter contracts, smaller transactions, far more privacy.

3. Tapscript

• Technical: Modernizes the script language; adds new opcodes (OP_CHECKSIGADD), removes legacy limits, and reserves future-upgrade space (OP_SUCCESSx opcodes).

• Simple Example:

  • More efficient n-of-n multi-sig logic, future protocol upgrades possible without risky forks.

• Key benefit: Clean foundation for smarter, more complex (yet secure) contracts.

Did Taproot Enable All Possible Bitcoin Contracts or zkProofs?

Short version: No—but it sets the stage.

• Taproot/Tapscript didn’t enable full covenants (restricting how coins move next), tokens, or native zero-knowledge proof (zkProof) verification on mainnet.

• But: The modular Tapscript design, plus Schnorr and MAST, make future upgrades far easier. Proposed opcodes like OP_CAT, OP_CHECKTEMPLATEVERIFY, or zkProof-verifiers can now be deployed safely using the reserved OP_SUCCESSx slots.

• Why this matters for zkProofs and smart contracts:

  • Advanced contracts and zkProofs often need to constrain future spends, automate state, or batch-validate complex logic.

  • With Taproot’s extensibility and privacy, these features can be added—meaning robust, private protocols (DeFi, tokens, bridges, on-chain privacy) could run at Bitcoin L1 in the future.

TL;DR — My Takeaways as a Builder

• Taproot doesn’t “enable everything now,” but it gives Bitcoin a vastly better toolkit and upgrade path.

• Schnorr/MAST/Tapscript mean smart contracts become smaller, private, and more versatile—but full covenants or zkProof-powered logic need further soft forks.

• The Taproot framework is forward-compatible—so Bitcoin’s future can include advanced applications you see on other chains, but in a more secure and conservative way.

As a Web3 dev, I’m excited:
Taproot is the door—future upgrades will determine how much we can unlock. If you want to build or invest ahead of the curve, follow covenant and zkProof proposal development closely.

https://bitcoinops.org/en/topics/schnorr-signatures/
https://developer.bitcoin.org/devguide/taproot.html