{"id": "card_crypto_perfect_secrecy", "kind": "reference", "title": "Perfect secrecy — the one-time pad", "body": "The one-time pad (XOR with a truly random key, as long as the message, used once) has provably perfect secrecy (Shannon, 1949): the ciphertext reveals nothing. Its key cost is why we usually fall back to hardness. Rests on the instruments (information theory).", "source": {"label": "Narrow Highway — cryptography", "url": "", "authority_tier": "engine_derived"}, "shelf": "codex", "box": "cryptography", "bands": ["cryptography", "pillar", "perfect_secrecy", "one map"], "subject": "Perfect secrecy — the one-time pad", "connections": [{"to_card_id": "card_floor_cryptography", "relationship": "part_of", "evidence": "a pillar of cryptography (Perfect secrecy)"}, {"to_card_id": "card_floor_the_instruments", "relationship": "connects_at", "evidence": "perfect secrecy is an information-theory result - the key entropy equals the message's"}], "author": "engine", "created_at": 0.0, "updated_at": 0.0, "visibility": "public", "lifecycle_stage": "public", "volatility": "permanent", "surface": "secular", "generated": false, "call": "codex.cryptography", "facets": {"subject": ["one map", "perfect_secrecy", "pillar"]}, "presentation": {"glyph": "•", "kind_label": "cryptography", "by": "Narrow Highway — cryptography", "authority": "engine_derived", "posted": "", "standing": ""}, "neighbors": [{"id": "card_floor_cryptography", "title": "Cryptography — public keys and hard problems", "relationship": "part of", "why": "a pillar of cryptography (Perfect secrecy)", "href": "/card/card_floor_cryptography", "resolved": true}, {"id": "card_floor_the_instruments", "title": "The instruments — every verifier and validator, and where they join", "relationship": "connects at", "why": "perfect secrecy is an information-theory result - the key entropy equals the message's", "href": "/card/card_floor_the_instruments", "resolved": true}], "house": {"door": "FIND", "kind": "card", "trail": "connections", "seal": "/card/card_crypto_perfect_secrecy", "next_step": {"do": "follow a connection: what this card rests on, and what rests on it", "door": "FIND", "tool": "card_connections", "params": {"id": "card_crypto_perfect_secrecy"}}, "ends": "a verdict or a card · the trail · a seal · one next step"}}