Recovery makes more sense once you know how MultiBit is built. This guide covers the technology behind it, how it stores your Bitcoin keys, and why it's structured the way it is.
SPV: Simplified Payment Verification
MultiBit was one of the first "lightweight" Bitcoin wallets, using a technology called Simplified Payment Verification (SPV). Unlike full nodes that download the entire Bitcoin blockchain (now over 500 GB), SPV wallets take a shortcut.
How SPV Works
- Block Headers Only: Instead of downloading every transaction ever made, MultiBit only downloads block headers - small 80-byte summaries of each block.
- Bloom Filters: MultiBit tells network peers which addresses it's interested in using probabilistic filters, so peers only send relevant transactions.
- Merkle Proofs: When MultiBit receives a transaction, it verifies it's included in a block using a cryptographic proof, without needing the full block.
- Trust Trade-off: SPV provides less security than a full node but is much more convenient for everyday users.
The SPV chain data is stored locally in a .spvchain file. This file can become corrupted and often needs to be deleted during troubleshooting. Deleting it forces MultiBit to re-sync from scratch (which no longer works properly since the network shutdown).
Wallet File Structure
MultiBit stores your Bitcoin private keys in wallet files. Knowing how these files are laid out makes recovery far less risky.
.wallet Files (MultiBit Classic)
The primary wallet file in MultiBit Classic. Contains:
- • Private keys (encrypted with your password)
- • Public keys and addresses
- • Transaction history metadata
- • Wallet settings and labels
Location: User-specified or in the MultiBit data directory
.key Files (Exported Keys)
Created when you export private keys from MultiBit Classic:
- • Contains one or more private keys in WIF format
- • May be encrypted (.key) or plaintext
- • .key.aes files are encrypted with AES
- • Can be imported directly into other wallets
.wallet.aes Files (Double Encrypted)
Some MultiBit installations use additional AES encryption:
- • Two layers of encryption for extra security
- • Requires correct password to decrypt
- • More complex recovery process
mbhd.wallet.aes (MultiBit HD)
MultiBit HD uses a different structure:
- • Contains encrypted seed (12 words derive all keys)
- • Uses BIP39/BIP44 standards
- • mbhd.yaml contains wallet configuration
- • All addresses derived from master seed
Data Directory Structure
MultiBit stores all its data in a specific directory:
# MultiBit Classic Data Directory
Windows: %APPDATA%\MultiBit\
macOS: ~/Library/Application Support/MultiBit/
Linux: ~/.multibit/
# MultiBit HD Data Directory
Windows: %APPDATA%\MultiBitHD\
macOS: ~/Library/Application Support/MultiBitHD/
Linux: ~/.MultiBitHD/
Typical Directory Contents
├── multibit.properties # Configuration
├── multibit.spvchain # Blockchain cache
├── multibit.checkpoints # Sync checkpoints
├── multibit.wallet # Default wallet
├── multibit-data/ # Additional data
├── log/ # Log files
└── rolling-backup/ # Automatic backups
Encryption and Security
MultiBit uses industry-standard encryption to protect your private keys:
Password-Based Encryption
Your wallet password is used to derive an encryption key using scrypt (a password-based key derivation function). This key encrypts your private keys using AES-256. Without the correct password, the private keys cannot be decrypted.
Key Derivation (HD Only)
MultiBit HD uses hierarchical deterministic (HD) key generation:
- • 12-word seed phrase → Master key
- • Master key → Unlimited child keys (using BIP32)
- • Derivation path: m/0'/0 for receiving, m/0'/1 for change
- • Knowing the seed = knowing all past and future keys
Network Architecture (Historical)
When MultiBit was operational, it connected to the Bitcoin network through:
Peer Discovery
- DNS Seeds: Hardcoded domain names that resolve to active Bitcoin nodes. These were maintained by the Bitcoin community but MultiBit's specific seeds may no longer work.
- Peer Exchange: Once connected to one peer, MultiBit would learn about other peers from the network.
- Fallback Nodes: A list of hardcoded IP addresses as last resort. These are now outdated.
Why MultiBit Can't Sync Anymore
Since MultiBit was discontinued in 2017:
- • DNS seeds have changed and no longer point to compatible nodes
- • The Bitcoin protocol has evolved with new features MultiBit doesn't understand
- • Checkpoint data is outdated, making sync from scratch nearly impossible
- • No one is maintaining infrastructure to support MultiBit clients
Why This Matters for Recovery
Understanding MultiBit's architecture helps with recovery because:
Your Keys Are Local
Private keys are stored in files on your computer, not on any server. As long as you have the files and password, recovery is possible.
Sync ≠ Ownership
You don't need MultiBit to sync to own your Bitcoin. Your keys control your coins regardless of what any software displays.
Standard Formats
MultiBit uses standard Bitcoin key formats. Extracted keys can be imported into any compatible wallet like Electrum.
Multiple Recovery Paths
Most users land here with one of three things: a seed phrase, a wallet file, or exported keys. Each has its own recovery path.