| 1 | // Sealing to a public key, against vectors/contra-v1.json ("handoff"). |
| 2 | // |
| 3 | // The device handoff is the one place a secret travels through the server, so |
| 4 | // the JS half of it is pinned to the same bytes the Go half is — generated by |
| 5 | // neither, in vectors/gen/gen.c against OpenSSL, itself checked against |
| 6 | // RFC 5903 before it may emit anything. |
| 7 | |
| 8 | import { test } from "node:test"; |
| 9 | import assert from "node:assert/strict"; |
| 10 | import { readFileSync } from "node:fs"; |
| 11 | import { fileURLToPath } from "node:url"; |
| 12 | import { dirname, join } from "node:path"; |
| 13 | |
| 14 | const here = dirname(fileURLToPath(import.meta.url)); |
| 15 | const mod = (name) => join(here, "..", "internal", "contra", "static", "crypto", name); |
| 16 | |
| 17 | const { toHex, fromHex } = await import(mod("bytes.js")); |
| 18 | const { deriveP256 } = await import(mod("p256.js")); |
| 19 | const { aad, OBJECT_HANDOFF } = await import(mod("sealed.js")); |
| 20 | const ecies = await import(mod("ecies.js")); |
| 21 | |
| 22 | const V = JSON.parse(readFileSync(join(here, "..", "vectors", "contra-v1.json"), "utf8")); |
| 23 | const H = V.handoff; |
| 24 | |
| 25 | test("handoff: both keypairs derive from their published seeds", async () => { |
| 26 | for (const [name, seed, scalar, pub] of [ |
| 27 | ["recipient", H.recipient_seed_hex, H.recipient_scalar_hex, H.recipient_public_hex], |
| 28 | ["ephemeral", H.ephemeral_seed_hex, H.ephemeral_scalar_hex, H.ephemeral_public_hex], |
| 29 | ]) { |
| 30 | const key = await deriveP256(fromHex(seed)); |
| 31 | assert.equal(toHex(key.scalar), scalar, `${name} scalar`); |
| 32 | assert.equal(toHex(key.publicKey), pub, `${name} public key`); |
| 33 | } |
| 34 | }); |
| 35 | |
| 36 | // Both directions. A one-sided check would pass on something that is not |
| 37 | // actually Diffie-Hellman. |
| 38 | test("handoff: ECDH agrees from both sides", async () => { |
| 39 | const fwd = await ecies.ecdh(fromHex(H.ephemeral_scalar_hex), fromHex(H.recipient_public_hex)); |
| 40 | assert.equal(toHex(fwd), H.shared_secret_hex, "sender side"); |
| 41 | |
| 42 | const back = await ecies.ecdh(fromHex(H.recipient_scalar_hex), fromHex(H.ephemeral_public_hex)); |
| 43 | assert.equal(toHex(back), H.shared_secret_hex, "recipient side"); |
| 44 | }); |
| 45 | |
| 46 | test("handoff: the derived key, the AAD and the sealed bytes", async () => { |
| 47 | const key = await ecies.eciesKey( |
| 48 | fromHex(H.ephemeral_public_hex), |
| 49 | fromHex(H.recipient_public_hex), |
| 50 | fromHex(H.shared_secret_hex)); |
| 51 | assert.equal(toHex(key), H.key_hex, "handoff key"); |
| 52 | |
| 53 | const a = aad(fromHex(H.account_id_hex), H.object_type, |
| 54 | fromHex(H.recipient_public_hex), H.version); |
| 55 | assert.equal(toHex(a), H.aad_hex, "handoff AAD"); |
| 56 | |
| 57 | const { seal } = await import(mod("sealed.js")); |
| 58 | const sealed = await seal(key, fromHex(H.nonce_hex), a, fromHex(H.plaintext_hex)); |
| 59 | assert.equal(toHex(sealed.slice(0, -16)), H.ciphertext_hex, "ciphertext"); |
| 60 | assert.equal(toHex(sealed.slice(-16)), H.tag_hex, "tag"); |
| 61 | }); |
| 62 | |
| 63 | // sealTo mints its own ephemeral key and nonce, so it cannot be checked |
| 64 | // against fixed bytes. What can be checked is the property that matters. |
| 65 | test("handoff: an envelope opens for its device and for nobody else", async () => { |
| 66 | const recipientPublic = fromHex(H.recipient_public_hex); |
| 67 | const recipientScalar = fromHex(H.recipient_scalar_hex); |
| 68 | const accountKey = fromHex(H.plaintext_hex); |
| 69 | const a = aad(fromHex(H.account_id_hex), OBJECT_HANDOFF, recipientPublic, 1); |
| 70 | |
| 71 | const envelope = await ecies.sealTo(recipientPublic, a, accountKey); |
| 72 | assert.equal(envelope.length, 65 + 12 + accountKey.length + 16, "envelope length"); |
| 73 | |
| 74 | const got = await ecies.openFrom(recipientScalar, recipientPublic, a, envelope); |
| 75 | assert.equal(toHex(got), H.plaintext_hex, "round trip"); |
| 76 | |
| 77 | const other = await deriveP256(fromHex(H.ephemeral_seed_hex)); |
| 78 | await assert.rejects( |
| 79 | () => ecies.openFrom(other.scalar, other.publicKey, a, envelope), |
| 80 | "a different device must not open an envelope sealed to another"); |
| 81 | |
| 82 | // The AAD names the recipient, so the server cannot relay one envelope on. |
| 83 | const wrong = aad(fromHex(H.account_id_hex), OBJECT_HANDOFF, other.publicKey, 1); |
| 84 | await assert.rejects( |
| 85 | () => ecies.openFrom(recipientScalar, recipientPublic, wrong, envelope), |
| 86 | "an envelope must not open under an AAD naming a different device"); |
| 87 | }); |
| 88 | |
| 89 | test("handoff: the Go and JS halves seal for each other", async () => { |
| 90 | // A fresh ephemeral pair from the browser side, opened with the scalar it |
| 91 | // kept — the exact shape the fresh device runs. |
| 92 | const device = await ecies.newEphemeral(); |
| 93 | assert.equal(device.publicKey.length, 65); |
| 94 | assert.equal(device.publicKey[0], 0x04); |
| 95 | |
| 96 | const a = aad(fromHex(H.account_id_hex), OBJECT_HANDOFF, device.publicKey, 1); |
| 97 | const envelope = await ecies.sealTo(device.publicKey, a, fromHex(H.plaintext_hex)); |
| 98 | const got = await ecies.openFrom(device.scalar, device.publicKey, a, envelope); |
| 99 | assert.equal(toHex(got), H.plaintext_hex); |
| 100 | }); |
| 101 | |
| 102 | test("handoff: a truncated envelope is refused before any key work", async () => { |
| 103 | const recipientPublic = fromHex(H.recipient_public_hex); |
| 104 | const a = aad(fromHex(H.account_id_hex), OBJECT_HANDOFF, recipientPublic, 1); |
| 105 | await assert.rejects( |
| 106 | () => ecies.openFrom(fromHex(H.recipient_scalar_hex), recipientPublic, a, |
| 107 | new Uint8Array(40)), |
| 108 | /too short/); |
| 109 | }); |
| 110 | |
amadan