Dev meeting walkthrough of CAP-87: Soroban adds post-quantum signature support. ML-DSA chosen for enterprise adoption and efficiency. Three variants (44/65/87) with specific key and signature sizes. Implementation costs and library selection discussed.
Stellar implements post-quantum cryptography as part of its quantum preparedness plan. CAP-87 adds ML-DSA signature support to Soroban smart contracts, enabling smart wallets to adopt quantum-resistant signatures before large-scale quantum computers emerge. ML-DSA was selected over alternatives like SLH-DSA and FALCON because it is already widely adopted by enterprises (Google, Amazon, Cloudflare) and offers smaller signature sizes than hash-based alternatives, a critical advantage for blockchain where signatures must be included on-chain. The implementation adds three signature verification functions (ML-DSA-44, 65, 87) with identical interfaces. Each variant has specific key and signature sizes: ML-DSA-44 uses 1312-byte keys and 2420-byte signatures. Verification is computationally efficient, with most work happening in key decoding.
