5.Experimental Notes: Alice → Bob → Dave Two-Hop Transfer

📋 Experiment Overview

Experiment Objective: Verify RGB protocol's multi-hop transfer capability, complete Alice → Bob → Dave two-hop transfer path

Experiment Time: 2025-08-19 23:55 - 2025-08-20 00:18

Final Result: ✅ Complete Success

🎯 Experiment Goals

1. Create Third-Party Wallet - Introduce Dave as a new participant
2. Verify Multi-Hop Path - Confirm RGB can support complex transfer networks
3. Test Invoice Reuse Risk - Understand RGB invoice security mechanism
4. Complete Process Verification - From invoice generation to on-chain confirmation

🏗️ Experiment Environment

Infrastructure

• Bitcoin Network: regtest (local testnet)
• RGB Version: v0.11.0-beta.9
• Esplora API: http://localhost:3002 (opens in a new tab)
• Docker Environment: bitlight-local-env

Participant Wallets

Contract Information

• Contract ID: rgb:BppYGUUL-Qboz3UD-czwAaVV-!!Jkr1a-SE1!m1f-Cz$b0xs
• Token Name: TEST
• Total Supply: 100,000,000,000 (fixed supply)
• Interface Type: RGB20Fixed

📝 Detailed Experiment Steps

Step 1: Dave Wallet Creation and Setup

1.1 Create Dave's Bitcoin Wallet

make dave-cli
# Select RGB Descriptor 9/*
# Get address: bcrt1pq4vz5369ctpt3mj96ey0k2dewwlh2x6gt3qrq2drtalwddac7vasjgmuzp
 

1.2 Send Bitcoin to Dave

make core-cli
load_wallet
send bcrt1pq4vz5369ctpt3mj96ey0k2dewwlh2x6gt3qrq2drtalwddac7vasjgmuzp 1
mint 1
 

Result: Dave receives 1 BTC, transaction ID: 75cd19134f6fbbe9dc9cd2c1ff1917deff0523ea8e765c6130451d081e70d318

1.3 Create Dave's RGB Wallet

rgb -d .dave -n regtest create default --tapret-key-only "[4a2358bd/86'/1'/0']tpubDCJSBWsVBQLHNJG4KuMgLLH6vhVdX1YCq3VLsjQxmLuQtRwzcd6LZw44h5yU6R6iGrCB8bVVt7Yoy5DWURUjBz3Y74DNpy8T1scWEUXTGpU/<0;1;9;10>/*" --esplora="http://localhost:3002"
 

1.4 Import RGB Contract

rgb -d .dave -n regtest import ../bitlight-rgb20-contract/test/rgb20-simplest.rgb --esplora="http://localhost:3002"
 

Verification Result: Dave successfully imported contract, Owned section is empty (no tokens received yet)

Step 2: RGB Transfer Process

2.1 Dave Generates Invoice 📋

python experiment2_bob_to_dave_complete.py
 

Invoice Content:

rgb:BppYGUUL-Qboz3UD-czwAaVV-!!Jkr1a-SE1!m1f-Cz$b0xs/RGB20Fixed/YFaF+bcrt:utxob:0EkaEhCY-7MiMA0F-pZjg1FF-eOpKMvD-dohVtt6-J3NH1fm-3lpa7

2.2 Bob Creates Transfer 📤

Generated Files:

• bob_to_dave_20250820_001323.consignment (proof package)
• bob_to_dave_20250820_001323.psbt (Bitcoin transaction)

Transfer Amount: 500 RGB tokens

2.3 Dave Validates and Accepts ✅

rgb -d .dave validate bob_to_dave_20250820_001323.consignment
rgb -d .dave accept -f bob_to_dave_20250820_001323.consignment
 

Result: Dave successfully validated and accepted transfer to local stash

Step 3: PSBT Signing Challenge and Solution

3.1 Initial Signing Failure ❌

Problem: Automated signing script fails on all derivation paths attempted Root Cause Analysis:

• PSBT references UTXO: 2f8eb2dd9caac7d414368b2c30adf7cb46df4bbfc49fee8f2fdb4cbd2da36bd9:0
• This UTXO corresponds to address: &9/0 (branch=9, index=0)
• Although signing script tried the correct path, wallet processing logic had issues

3.2 Debugging Analysis 🔍

Key Discovery:

• All of Bob's RGB tokens bound to same seal: bc:tapret1st:2f8eb2dd9caac7d414368b2c30adf7cb46df4bbfc49fee8f2fdb4cbd2da36bd9:0
• Corresponding Bitcoin UTXO: 2f8eb2dd9caac7d414368b2c30adf7cb46df4bbfc49fee8f2fdb4cbd2da36bd9:0 (1 BTC)
• This UTXO at address &9/0, requires private key for branch=9, index=0

3.3 Manual Signing Success ✅

Solution: Directly use bitcoin-cli for PSBT processing

# Create dedicated wallet
cli(['createwallet', 'wallet_name=final_bob', 'descriptors=false'])
 
# Import correct private key (branch=9, index=0)
wif = derive_wif_from_tprv(bob_tprv, 9, 0)
cli(['importprivkey', wif, 'final-key', 'false'], wallet='final_bob')
 
# Process PSBT
proc_result = cli(['walletprocesspsbt', psbt_b64, 'true'], wallet='final_bob')
fin_result = cli(['finalizepsbt', f'psbt={proc_data["psbt"]}', 'extract=true'])
 
# Broadcast transaction
txid = cli(['sendrawtransaction', fin_data['hex']])
 

Success Result:

• ✅ PSBT signing completed
• ✅ Transaction broadcast successful
• TXID: 24d14f5cdbbf0487269ed36bda89629f4bae71820f41af72ab7117d641233ccf

📊 Final State Verification

Pre-Transfer State

Post-Transfer State (Block 228 Confirmed)

State Verification Commands

rgb -d .bob state $CID RGB20Fixed --sync --esplora="http://localhost:3002"
rgb -d .dave state $CID RGB20Fixed --sync --esplora="http://localhost:3002"
 

🔬 In-Depth Technical Analysis

RGB Protocol Mechanism Verification

1. Tapret Commitment Mechanism

• Principle: RGB state is committed through Taproot public key tweak
• Verification: Each RGB transfer corresponds to a unique tapret seal
• Example: bc:tapret1st:24d14f5c... binds to a specific Bitcoin UTXO

2. Client-Side Validation Model

• Process: Dave independently verifies cryptographic proofs of the transfer
• Security: Does not rely on third parties, completely decentralized verification
• Result: Dave only accepts transfer to local stash after validation passes

3. UTXO Consolidation Optimization

• Problem: Bob's original 3 separate RGB UTXOs cause fragmentation
• Solution: RGB protocol automatically consolidates UTXOs during transfer
• Effect: Bob consolidated from 3 UTXOs to 1, improving efficiency

4. Atomicity Guarantee

• Mechanism: RGB state transitions are atomically bound to Bitcoin transactions
• Verification: Same witness transaction 24d14f5c... simultaneously updates Bob and Dave's states
• Security: Bitcoin network consensus guarantees atomicity of RGB state transitions

⚠️ Issues and Challenges

1. PSBT Signing Complexity

Problem: Automated signing script failure Root Cause:

• Difficulty identifying derivation paths for RGB UTXOs
• Timing issues with wallet creation and loading
• Wallet isolation between different tools

Solution:

• Manual analysis of RGB state to determine correct derivation path
• Use dedicated wallet to avoid conflicts
• Simplified direct CLI approach

2. State Sync Delay

Phenomenon: State display inconsistent after transfer completion Cause: RGB client needs time to sync on-chain state Solution: State displays correctly after mining block for confirmation

3. Toolchain Complexity

Challenge: Need to coordinate RGB CLI, Python scripts, Docker containers and other components Improvement: Unified toolchain and better error handling

💡 Lessons Learned

Technical Insights

1. Deep Integration of RGB with Bitcoin
   • RGB is not an "add-on layer" to Bitcoin, but a "native extension" of Bitcoin
   • Every RGB operation must have corresponding Bitcoin transaction support
2. Power of Client-Side Validation
   • Receiver has complete control over whether to accept transfer
   • No need to trust sender or network, autonomously validates all proofs
3. Advantages of UTXO Model
   • Natural support for concurrency and sharding
   • Automatic privacy protection and state isolation

Practical Experience

1. Debugging Strategy
   • Triple-check RGB state + Bitcoin UTXO + derivation path
   • Verify each step incrementally rather than end-to-end testing
   • Keep intermediate files for analysis
2. Tool Usage Tips
   • RGB CLI's esplora parameter is mandatory
   • Special characters in contract ID need shell escaping
   • bitcoin-cli's wallet parameter must be explicitly specified
3. State Management
   • Mine blocks promptly to confirm state
   • Distinguish between tentative and confirmed states
   • Understand RGB's finality semantics

🚀 Future Experiment Directions

Based on Experiment 's success, the following in-depth experiments can be conducted:

Experiment 2: RGB20Fixed Minting Restrictions

• Verify fixed supply contract limitations
• Understand why Bob cannot mint new tokens
• Compare differences between RGB interfaces

Experiment 3: Asset Recovery Drill

• Consignment file loss recovery
• Stash state database reconstruction
• Private key loss scenario analysis

Experiment 4: Network Exception Handling

• PSBT handling with insufficient fees
• RBF (Replace-By-Fee) mechanism
• Mempool congestion response

Experiment 5: Security Testing

• Double-spend attack attempts
• Invoice reuse risk verification
• Receiver rejection attack

📁 Experiment File Checklist

Generated Files

bob_to_dave_20250820_001323.consignment  # RGB proof package
bob_to_dave_20250820_001323.psbt         # Bitcoin PSBT
experiment2_bob_to_dave_complete.py      # Automation script
psbt_signer.py                           # PSBT signing tool

Key Transactions

• Transfer Transaction: 24d14f5cdbbf0487269ed36bda89629f4bae71820f41af72ab7117d641233ccf
• Confirmation Block: 228 (2025-08-19 16:18:48)
• Dave Receive UTXO: 75cd19134f6fbbe9dc9cd2c1ff1917deff0523ea8e765c6130451d081e70d318:1

🎯 Conclusion

Experiment successfully verified RGB protocol's multi-hop transfer capability. By creating third-party participant Dave and completing Bob→Dave 500 token transfer, we gained deep understanding of:

1. RGB Scalability: Supports arbitrarily complex transfer networks
2. Security Model: Client-side validation ensures decentralized security
3. Efficiency Optimization: UTXO consolidation reduces on-chain footprint
4. Toolchain Maturity: Although complex, functionally complete

This lays a solid foundation for more complex RGB applications in the future, proving RGB's tremendous potential as Bitcoin's native smart contract layer.

Experiment Record Time: 2025-08-20

Experiment Environment: bitlight-local-env + RGB v0.11.0-beta.9

Experiment Status: ✅ Complete Success