Stanko K.R.
95 lines
3.8 KiB
Ruby
95 lines
3.8 KiB
Ruby
module WebauthnTestHelper
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# Fixed EC P-256 key pair for WebAuthn tests.
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WEBAUTHN_PRIVATE_KEY = OpenSSL::PKey::EC.new(
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[ "307702010104201dd589de7210b3318620f32150e3012cce021519df1d6e9e01" \
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"0471146d395cdca00a06082a8648ce3d030107a14403420004116847fe19e1ad" \
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"4471ab9980d7ff9cc1e4c7cb7a3af00e082b64fcd84f5ae70114c2495eef16f" \
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"542b5e57dd1b263661624e3cf28f581b57a441edbd756a41d0e" ].pack("H*")
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)
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# Pre-encoded COSE EC2/ES256 public key (CBOR) for the key above.
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# {1: 2, 3: -7, -1: 1, -2: <x 32 bytes>, -3: <y 32 bytes>}
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COSE_PUBLIC_KEY = [ "a5010203262001215820116847fe19e1ad4471ab9980d7ff9cc1" \
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"e4c7cb7a3af00e082b64fcd84f5ae70122582014c2495eef16f542b5e57dd1b2" \
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"63661624e3cf28f581b57a441edbd756a41d0e" ].pack("H*")
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# CBOR prefix for {"fmt": "none", "attStmt": {}, "authData": bytes(164)}.
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# Auth data is always 164 bytes: rp_id_hash(32) + flags(1) + sign_count(4)
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# + aaguid(16) + credential_id_length(2) + credential_id(32) + cose_key(77).
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ATTESTATION_OBJECT_CBOR_PREFIX =
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[ "a363666d74646e6f6e656761747453746d74a068617574684461746158a4" ].pack("H*")
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private
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def request_webauthn_challenge(purpose: "authentication")
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untenanted { post my_passkey_challenge_url, params: { purpose: purpose } }
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response.parsed_body["challenge"]
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end
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def webauthn_challenge(purpose: nil)
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ActionPack::WebAuthn::PublicKeyCredential::Options.new(challenge_purpose: purpose).challenge
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end
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def webauthn_private_key
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WEBAUTHN_PRIVATE_KEY
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end
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def build_attestation_params(challenge:)
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credential_id = SecureRandom.random_bytes(32)
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auth_data = build_attestation_auth_data(credential_id: credential_id)
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{
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passkey: {
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client_data_json: webauthn_client_data_json(challenge: challenge, type: "webauthn.create"),
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attestation_object: Base64.urlsafe_encode64(ATTESTATION_OBJECT_CBOR_PREFIX + auth_data, padding: false),
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transports: [ "internal" ]
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}
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}
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end
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def build_assertion_params(challenge:, credential:, sign_count: 1)
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client_data_json = webauthn_client_data_json(challenge: challenge, type: "webauthn.get")
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authenticator_data = build_assertion_auth_data(sign_count: sign_count)
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signature = webauthn_sign(authenticator_data, client_data_json)
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{
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passkey: {
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id: credential.credential_id,
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client_data_json: client_data_json,
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authenticator_data: Base64.urlsafe_encode64(authenticator_data, padding: false),
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signature: Base64.urlsafe_encode64(signature, padding: false)
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}
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}
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end
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def webauthn_client_data_json(challenge:, type:)
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{ challenge: challenge, origin: "http://www.example.com", type: type }.to_json
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end
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# Attestation auth data includes the attested credential (public key + credential ID).
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def build_attestation_auth_data(credential_id:)
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[
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Digest::SHA256.digest("www.example.com"), # rp_id_hash
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[ 0x45 ].pack("C"), # flags: UP + UV + AT
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[ 0 ].pack("N"), # sign_count
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"\x00" * 16, # aaguid
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[ credential_id.bytesize ].pack("n"), # credential_id_length
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credential_id,
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COSE_PUBLIC_KEY
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].join.b
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end
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# Assertion auth data is simpler — no attested credential.
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def build_assertion_auth_data(sign_count:)
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[
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Digest::SHA256.digest("www.example.com"),
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[ 0x05 ].pack("C"), # flags: UP + UV
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[ sign_count ].pack("N")
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].join.b
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end
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def webauthn_sign(authenticator_data, client_data_json)
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signed_data = authenticator_data + Digest::SHA256.digest(client_data_json)
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WEBAUTHN_PRIVATE_KEY.sign("SHA256", signed_data)
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end
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end
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