Multikey ((top))

❌ Key management becomes complex – which slot holds which key? ❌ Some software assumes one key per token ❌ Limited storage (e.g., YubiKey 5 holds ≤ 25 resident FIDO2 keys)

Tagging systems, permissions lists, event participants, any “many-to-many” flattened into a document.

⭐⭐⭐⭐ (4/5) – essential for array query performance, but beware of index bloat. multikey

❌ Complexity – key management, coordination overhead ❌ Larger signatures or additional rounds of communication ❌ Not standardized across all systems

e.g., map[(region, product)] = sales . Some languages/libraries call this a multikey map when the key is an n-tuple. ❌ Key management becomes complex – which slot

❌ Standard library often missing (C++, Java, Python need custom or third-party) ❌ Memory overhead for multiple key mappings if done naively

: Once the computation is finished, the resulting ciphertext can only be decrypted if all participating users cooperate by providing a "partial decryption" using their respective secret keys. ❌ Complexity – key management, coordination overhead ❌

Protocols where multiple cryptographic keys are required to sign, decrypt, or authenticate. Examples:

is not a single technology but a pattern – storing or using multiple key values where normally one would suffice.