rawbit

rawBit Study Cohort — 10-Week Program

Build raw Bitcoin transactions from scratch using a visual, interactive tool.

---

Overview

The rawBit Study Cohort is a 10-week hands-on program where participants build raw Bitcoin transactions from scratch using rawBit — an open-source visual Bitcoin transaction builder and Script debugger. Participants connect inputs, keys, and scripts on a visual canvas to construct transactions at the byte level, progressing from legacy P2PKH all the way to Taproot.

This cohort is the natural next step after Bitcoin Dojo — where you learned the cryptographic primitives, here you apply them to build real transactions.

rawBit is created by @rawBit_io and ships with 12 built-in interactive lessons. Code Orange runs a structured study cohort around these lessons with weekly group calls, peer accountability, and mentor support.

Prerequisites

• Completion of Bitcoin Dojo or equivalent knowledge of:
  • Elliptic curve cryptography and ECDSA
  • Bitcoin address formats (P2PKH, P2SH, P2WPKH)
  • Basic transaction structure (inputs, outputs, scripts)
• OR: Strong self-taught understanding of Bitcoin transaction fundamentals
• A laptop with a modern web browser (rawBit runs in-browser)

Format

Component	Details
Duration	10 weeks
Time commitment	4-6 hours per week
Weekly calls	Via Discord (time TBD per cohort)
Tool	rawBit visual transaction builder
Level	Intermediate (post-Bitcoin Dojo)

How It Works

1. Each week: 1-2 rawBit lessons assigned + supplementary readings
2. Self-study: Work through the interactive lessons in rawBit — drag, connect, build, inspect
3. Weekly call: Group discussion and live debugging of transaction construction
4. Challenge exercises: Build increasingly complex transactions without the guided mode
5. Final project: Construct a complex multi-condition Taproot transaction from scratch

---

Week-by-Week Syllabus

Week 1: rawBit Setup & Legacy Transactions (P2PK, P2PKH)

rawBit Lessons: Lesson 1 (P2PK), Lesson 2 (P2PKH)

Topics:

• rawBit interface: canvas, nodes, connections, inspector
• Pay-to-Public-Key (P2PK): the simplest transaction type
• Pay-to-Public-Key-Hash (P2PKH): why hashing the public key matters
• Building a complete transaction: input → scriptSig → output → scriptPubKey
• Inspecting the raw hex output byte by byte

Exercises:

1. Build a P2PK transaction in rawBit — send coins to a public key and spend them
2. Build a P2PKH transaction — compare the script structure to P2PK
3. Export the raw hex and decode it manually, labelling every field

Discussion:

• Why did Bitcoin move from P2PK to P2PKH? What's the security improvement?

---

Week 2: Multisig Transactions

rawBit Lessons: Lesson 3 (Multisig), Lesson 4 (P2SH fundamentals)

Topics:

• OP_CHECKMULTISIG: how multi-signature verification works in Script
• The off-by-one bug and OP_0 workaround
• 2-of-3 multisig: building and spending
• Pay-to-Script-Hash (P2SH): hiding complex scripts behind a hash
• Redeem scripts and their role in P2SH

Exercises:

1. Build a 2-of-3 bare multisig transaction in rawBit
2. Wrap the same multisig in P2SH — compare the output scripts
3. Spend from the P2SH output by providing the redeem script and signatures

---

Week 3: Timelocks

rawBit Lessons: Lesson 5 (nLockTime/nSequence), Lesson 6 (OP_CHECKLOCKTIMEVERIFY)

Topics:

• Absolute timelocks: nLockTime (transaction-level)
• OP_CHECKLOCKTIMEVERIFY (CLTV): script-level absolute timelock
• Relative timelocks: nSequence and OP_CHECKSEQUENCEVERIFY (CSV)
• Use cases: payment channels, inheritance, escrow

Exercises:

1. Build a transaction with an nLockTime set to a future block height
2. Build a CLTV-locked output that can only be spent after block N
3. Build a CSV-locked output with a relative timelock of 144 blocks (~1 day)
4. Combine timelocks with multisig: "Alice can spend immediately with 2-of-3, OR Bob can spend alone after 1000 blocks"

---

Week 4: OP_RETURN & Data Anchoring

rawBit Lesson: Lesson 7 (OP_RETURN anchors)

Topics:

• OP_RETURN: provably unspendable outputs
• Embedding data in the Bitcoin blockchain
• Size limits and relay policies
• Use cases: timestamping, commitments, coloured coins history
• Ethical and practical considerations of blockchain data

Exercises:

1. Build a transaction with an OP_RETURN output containing a message
2. Build a commitment scheme: hash a document, embed the hash in OP_RETURN
3. Explore a real mainnet transaction with OP_RETURN data

---

Week 5: Transaction Malleability & Payment Channels

rawBit Lesson: Lesson 8 (Transaction malleability), Lesson 9 (Payment channels)

Topics:

• Transaction malleability: how it works, why it's dangerous
• How scriptSig manipulation changes the txid without invalidating the transaction
• Payment channels: the foundational concept behind Lightning
• Building a simple unidirectional payment channel
• Why malleability breaks payment channels (motivating SegWit)

Exercises:

1. Demonstrate transaction malleability: modify a scriptSig encoding and show the txid changes
2. Build a simple payment channel: funding tx + commitment txs + settlement tx
3. Show how malleability would break the commitment transaction chain

---

Week 6: SegWit Transactions (P2WPKH)

rawBit Lessons: Lesson 10 (P2WPKH)

Topics:

• Segregated Witness: moving the witness outside the txid calculation
• P2WPKH (Pay-to-Witness-Public-Key-Hash): native SegWit
• Witness field structure
• Weight units vs virtual bytes
• The witness discount: why witness data is cheaper

Exercises:

1. Build a P2WPKH transaction in rawBit — compare structure to P2PKH
2. Calculate the weight and vbytes of your SegWit transaction
3. Build the same transaction as legacy P2PKH — compare sizes and fees
4. Verify that the witness data is excluded from the txid calculation

---

Week 7: SegWit Scripts (P2WSH)

rawBit Lessons: Lesson 11 (P2WSH, nested SegWit)

Topics:

• P2WSH (Pay-to-Witness-Script-Hash): SegWit version of P2SH
• Witness scripts vs redeem scripts
• Nested SegWit (P2SH-P2WPKH): backward compatibility
• When to use P2WPKH vs P2WSH vs nested SegWit

Exercises:

1. Build a P2WSH 2-of-3 multisig in rawBit
2. Build the same multisig as P2SH — compare witness data vs scriptSig
3. Build a nested SegWit (P2SH-P2WPKH) transaction

---

Week 8: Taproot Basics

rawBit Lessons: Lesson 12 (Taproot)

Topics:

• Schnorr signatures (BIP340): linearity and key aggregation
• Taproot (BIP341): key-path vs script-path spending
• The Taproot tweak: how a public key commits to a script tree
• P2TR (Pay-to-Taproot) output structure
• Why key-path spends look identical to regular payments (privacy)

Exercises:

1. Build a Taproot (P2TR) key-path spend in rawBit
2. Build a Taproot output with a script tree
3. Spend via the script-path — provide the script, control block, and Merkle proof
4. Compare the on-chain footprint of key-path vs script-path

---

Week 9: Advanced Taproot & MuSig2

Topics:

• MuSig2: interactive multi-signature with a single public key
• Taproot script trees: building complex spending conditions
• MAST (Merkelized Abstract Syntax Tree) via Taproot
• Combining Taproot with timelocks for complex contracts
• Tapscript (BIP342): new opcodes for Taproot

Exercises:

1. Design a Taproot output with 3 spending conditions in the script tree
2. Build an escrow contract: "Alice+Bob key-path, OR Alice after 1000 blocks, OR Bob+mediator"
3. Calculate the Merkle root of a script tree with 4 leaves

---

Week 10: Final Project & Graduation

Final Project: Build a complex, real-world Bitcoin transaction entirely from scratch in rawBit. Choose from:

1. Inheritance Vault: Taproot output where spouse can spend with 2-of-3 multisig immediately, OR a single heir key after 52,560 blocks (~1 year)
2. Atomic Swap: Construct both sides of a cross-chain atomic swap using HTLCs (Hash Time-Locked Contracts)
3. Lightning-style Channel: Full funding → commitment → revocation → settlement flow
4. Custom Design: Propose your own complex transaction design

Presentation: Each participant presents their final project:

1. What does the transaction do and why is it useful?
2. Walk through the script tree / spending conditions
3. What did building it teach you about Bitcoin?
4. What will you build or contribute to next?

---

After the Cohort

Graduates are ready to:

• Start contributing to Bitcoin transaction-related projects (BDK, rust-bitcoin, Bitcoin Core wallet)
• Build wallet software that constructs transactions correctly
• Review PRs involving transaction format changes
• Teach others using rawBit as a visual aid
• Continue to the Decoding Bitcoin cohort for Bitcoin Core contribution

---

Facilitator Guide

Before the Cohort

• Ensure all participants have rawBit running in their browser
• Confirm participants have completed Bitcoin Dojo or equivalent
• Set up Discord channel with weekly threads
• Coordinate with @rawBit_io for any tool updates or support

During the Cohort

• Post weekly lesson assignments every Sunday
• Host weekly calls — screen-share rawBit for live transaction building
• Encourage participants to export and share their transaction hex
• Pair struggling participants with faster learners

After the Cohort

• Host graduation presentations
• Connect graduates to relevant Good First Issues (especially BDK, rust-bitcoin transaction modules)
• Track graduate outcomes in PR Dashboard

---

Credits

• rawBit tool: rawBit.io — Visual Bitcoin TX builder & Script debugger
• Upstream textbook: Programming Bitcoin by Jimmy Song
• Partner: Code Orange Dev School in collaboration with rawBit

---

License

CC0 1.0 Universal. Public domain. Fork it, translate it, teach with it.