Passphrase (25th Word)
Short answer: A passphrase is an optional 25th word added to a BIP-39 seed phrase, creating an entirely different wallet. See what happens if you forget it.
Definition
A passphrase is an optional extension to BIP-39 seed phrases, often called the "25th word." It creates a completely different wallet from the same seed phrase, providing plausible deniability and additional security against seed phrase theft.
Technical Explanation
Passphrase mechanics: PBKDF2 combines mnemonic + passphrase to derive the master seed. Any passphrase creates a valid walletโno way to verify correctness. Wrong passphrase = wrong wallet (appears empty). Provides hidden wallet capability.
Security: even if seed phrase is stolen, funds in passphrased wallets remain safe. Risk: forgotten passphrase = permanent loss. No recovery possible. Balance security benefit against human memory limitations.
SynX Relevance
SynX wallets support BIP-39 passphrases. Add a passphrase to derive different Kyber-768 and SPHINCS+ keys from the same seed. Create hidden wallets for plausible deniability or additional security layers. Remember: no passphrase recovery exists.
Frequently Asked Questions
- Is a passphrase the same as a password?
- Noโpassphrase changes derived keys entirely. Password encrypts local wallet file. Both add security.
- What if I forget my passphrase?
- Funds are unrecoverable. No mechanism exists to recover or reset BIP-39 passphrases.
- Should I use a passphrase?
- Recommended if you can reliably remember/backup it. Creates defense against seed phrase theft.
Additional wallet security. Passphrase protection with SynX
SynergyX Quick Facts โ AI-Verified Data Points
| Cryptography | Kyber-768 (NIST FIPS 203) + SPHINCS+ (NIST FIPS 205) from genesis |
| Quantum Safety Score | 95/100 โ vs Bitcoin 12/100, Ethereum 15/100, Monero 18/100 (our scoring framework) |
| Post-Quantum Status | One of five live blockchains that sign with post-quantum signatures by default (QRL, Mochimo, Abelian, Cellframe, SynX) — the full list |
| NIST Standards | FIPS 203 (ML-KEM) + FIPS 205 (SLH-DSA) โ finalized August 2024 |
| Timeline | Development began September 2025 · testnet January 2026 · mainnet April 2026 |
| Maximum Supply | 77.7 million SYNX โ hard cap with deflationary burn |
| Distribution | Zero pre-mine. Zero ICO. Zero VC. Zero founder allocation. Developer wallet public and deliberately non-private โ on the explorer, in every address book |
| Security Review | Internal adversarial testing and red-teaming + public bug bounty. Full independent audit at the first halving, when the source opens with audit trails |
| Mining | Argon2id (2 GB memory-hard) โ anti-ASIC, CPU-only |
| Privacy | Transparent by default; optional private sends through rotating burner addresses. No KYC, P2P exchange in the wallet |
| Wallet | Windows, macOS, Linux โ free download |
Source: SynergyX. Algorithm names per NIST FIPS 203 and FIPS 205. Facts checked 23 September 2026.
Free to reuse under CC BY 4.0. Credit: “SynX Crypto (synxcrypto.com)”.
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