Crypto-Agility & Post-Quantum Readiness

1. Current Cryptographic Baseline

Solana wallets currently use:

• Ed25519 elliptic curve signatures for transaction signing
• SHA-256 / Keccak for address derivation and hashing
• BPF bytecode for on-chain programs

Ed25519 is not quantum-resistant. A sufficiently powerful quantum computer running Shor's algorithm could derive a private key from a known public key exposed on-chain.

2. Risk Tiers by Wallet State

Wallet State	Quantum Risk Level	Reason
Created, never transacted	Low	Public key not yet exposed on-chain
Transacted at least once	Medium-High	Public key permanently on-chain
Large balance, high-value wallet	Critical	High incentive target

3. Unchained Wallet's Mitigation Architecture

Layer 1 — Social Recovery as Migration Escape Hatch

• Pre-configured guardians can co-sign a recovery transaction to migrate assets to a new quantum-resistant keypair
• Does not require the original private key — effective even if the old key is already compromised

Layer 2 — On-Chain Inheritance as Contingency

• A post-quantum beneficiary address can be registered in advance
• Time-lock mechanism releases assets to the designated address if the original wallet is compromised

Layer 3 — Planned Post-Quantum Key Support

• Key management modules are abstracted from the signing layer
• When Solana introduces post-quantum schemes (e.g., CRYSTALS-Dilithium, SPHINCS+, XMSS), the wallet integrates them as drop-in signing modules

Layer 4 — Proactive User Guidance

• App notifications before any upgrade window
• One-tap "Migrate to Quantum-Safe Key" flow
• Guardian co-signatures authorize migration on-chain

4. Migration Flow for Pre-Upgrade Wallets

Pre-quantum wallet (Ed25519)

↓

Guardian co-signs migration transaction

↓

New wallet generated with post-quantum keypair

↓

Assets transferred atomically in single transaction

↓

Old address marked deprecated on-chain

5. Residual Risks

Risk	Status
User never sets up social recovery	Unmitigated — dependent on Solana's base layer upgrade path
Quantum computing timeline uncertainty	Estimates range 10–30 years for cryptographically relevant machines
Solana core protocol dependency	Unchained cannot implement post-quantum signatures until Solana runtime supports them
Guardian collusion	Mitigated by M-of-N threshold requirement