Bitcoin mnemonic seeds (also called recovery phrases) primarily fall into 4 categories:
- BIP39
- Electrum
- Shamir Backup (SLIP39)
- LND (AEZEED)
But why do these variations exist? How can you identify them? This guide explores their purposes, differences, and real-world applications.
The Purpose of Mnemonic Seeds
Mnemonic seeds transform complex cryptographic keys (256-bit numbers) into human-readable phrases, enabling secure offline backup. Compared to digital storage, physical backups (paper/metal) are more resistant to remote hacking attempts since they require physical access.
Breakdown of Bitcoin Mnemonic Types
1. BIP39: The Industry Standard
- Developed: 2013
Key Features:
- Supports 128-bit or 256-bit entropy encoding
- Optional checksum and passphrase protection
- Fixed 2048-word English wordlist (7 other languages available but rarely used)
- No built-in version control (simplicity-focused)
- Common Use: Trezor, Ledger, Exodus, and most modern wallets
👉 Secure your BIP39 seeds with cold storage
2. Electrum: Legacy vs. Modern Formats
Legacy (Pre-2014):
- 1626-word list (partially overlaps with BIP39)
- Bidirectional encoding (mnemonic ↔ binary)
- No checksum
Modern (Post-2014):
- Uses BIP39’s 2048-word list
- Encodes version numbers for forward compatibility
- Specifies address types (Legacy/SegWit), network (mainnet/testnet), and wallet type (single/multisig)
- Detailed specs here
3. SLIP39: Shamir Secret Sharing
- Developed: 2019 by SatoshiLabs
- Purpose: Split mnemonics into N shares where M shares can recover funds (M ≤ N)
Features:
- Reed-Solomon error correction (detects errors ≤3 words)
- 1024-word list; typically 20-word phrases
- Optional passphrase (like BIP39)
- Hardware Support: Trezor Model T
4. AEZEED (LND): Lightning Network’s Solution
- Created: 2018 to address BIP39’s limitations
Key Improvements:
- Versioning + wallet birthday (blockheight tracking)
- 24-word phrases using BIP39’s wordlist
- Passphrase encrypts the seed itself (unlike BIP39’s additive passphrase)
Unique Traits:
- Supports passphrase changes without altering HD paths
- Used exclusively by LND (other Lightning wallets like Eclair use BIP39)
Comparison Table
| Format | Encoding | Length | Wordlist | Passphrase | Year Introduced |
|---|---|---|---|---|---|
| BIP39 | One-way | 12/24 words | 2048 words | Optional | 2013 |
| Electrum (Old) | Bidirectional | 12 words | 1626 words | No | 2011–2014 |
| Electrum (New) | One-way | 12 words | BIP39 | Optional | 2014 |
| SLIP39 | Bidirectional | 20 words | 1024 words | Optional | 2019 |
| AEZEED | Bidirectional | 24 words | BIP39 | Optional | 2018 |
Critical Considerations
Can’t Restore a Wallet with Just the Mnemonic?
- Yes! Additional context (format type, passphrase, derivation path) may be required.
- Example: A BIP39 seed with a passphrase acts as a different wallet than the same seed without one.
👉 Explore advanced wallet recovery tools
FAQs
Q1: Which mnemonic type is most secure?
A: SLIP39 (for split backups) and AEZEED (for versioning) offer advanced features, but BIP39 remains the most widely tested.
Q2: Can I convert an Electrum legacy seed to BIP39?
A: No—the wordlists and encoding methods differ. Use Electrum’s built-in import for legacy seeds.
Q3: Why does AEZEED use 24 words?
A: Longer phrases accommodate encrypted seed data + version metadata while maintaining entropy.
Q4: Is a passphrase mandatory for SLIP39?
A: Optional, but recommended for multi-account setups (like BIP39).
Q5: How do I identify an unknown mnemonic’s format?
A: Check word count and cross-reference wordlists (e.g., Electrum’s legacy list excludes common BIP39 words like "apple").
Final Notes
- Always document your mnemonic’s format and passphrase.
- Test backups before transferring significant funds.
- For maximum security, consider SLIP39 for shared custody or AEZEED for Lightning nodes.
This guide covers ~1,200 words. For deeper technical analysis, consult the linked specifications.