発表する場所が無かったので供養… 個人の調査に基づいたものであり、Yubicoの見解ではありません。

1. YubiKey の
U2F, FIDO2 実装のナカミ
U2F/FIDO2 implementation of YubiKey

2. Wataru Haniyama
@watahani
3 years ago…
I worked at book store

3. マニアックな 話します
https://developers.yubico.com/U2F/Protocol_details/Key_generation.html

4. Implementation of U2F Host Library
It’s interesting
looking FIDO2 overall
from U2F (^^)/

5. TODAY I talk about U2F

6. TODAY I talk about U2F
and FIDO2

7. using publicKey

8. CTAP1 Security Points
Check App ID in
Authenticator, Client, Server
Make Private Key for Each
Applications

9. Yubico’s Implementation U2F
https://developers.yubico.com/U2F/Protocol_details/Key_generation.html

10. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
RP
Hash of ClientData
{ type: “webauthn.create”
origin: “example.com”,
challenge: “xxxxxxxxx”,
tokenBinding: { status: …} }

11. Registration
Generate Random Nonce
RNG
Device Secret
App ID Challenge
HMAC
0 0 0 0
https://developers.yubico.com/U2F/Protocol_details/Key_generation.html
Response
Attestation Certificate
Attestation Secret

12. Registration
Generate Random Nonce
RNG
Nonce
App ID
App ID Challenge
Generate Application Private Key
HMAC
0 0 0 0
https://developers.yubico.com/U2F/Protocol_details/Key_generation.html
Response
Device Secret

13. Registration
Generate Random Nonce
RNG
Nonce
Application Private Key Application Public Key
App ID
App ID Challenge
Generate Application Private Key
HMAC
0 0 0 0
https://developers.yubico.com/U2F/Protocol_details/Key_generation.html
ECDSA P-256
Response
Device Secret

14. Yubico’s Implementation U2F
Generate Credential ID
Application Private Key
Application Public Key
Nonce
App ID Challenge
HMAC
0 0 0 0
Response
Device Secret

15. Yubico’s Implementation U2F
Generate Credential ID
HASH MAC
Application Private Key
Nonce
App ID Challenge
HMAC
0 0 0 0
Response
Device Secret
Application Public Key

16. Yubico’s Implementation U2F
Generate Credential ID
HASH MAC
Application Private Key
Nonce
App ID Challenge
HMAC
0 0 0 0
Nonce
Response
Device Secret
Application Public Key

17. Yubico’s Implementation U2F
Generate Credential ID
HASH MAC
Application Private Key
Credential ID
Nonce
App ID Challenge
HMAC
0 0 0 0
Nonce
Response
Device Secret
Application Public Key

18. Yubico’s Implementation U2F
Generate Credential ID
HASH MAC
Application Private Key
Credential ID
Nonce
App ID Challenge
HMAC
0 0 0 0
Nonce
Response
Device Secret
Application Public Key
U2F protocol
KeyHandle

19. Attestation Statement fido-u2f
Attestation Certificate
Credential ID
ECDSAP256
App ID Challenge
0 0 0 0
Response
Attestation Secret
Application Public Key

20. Attestation Statement fido-u2f
Attestation Certificate
Credential ID
ECDSAP256
App ID
App ID Challenge
0 0 0 0
Challenge
Client Data
Response
Attestation Secret
Application Public Key

21. Attestation Statement fido-u2f
Credential ID
ECDSAP256
Application Public Key
Credential ID
App ID
Challenge
App ID Challenge
Client Data
0 0 0 0
Response
Application Public Key
Attestation Certificate
Attestation Secret

22. Attestation Statement fido-u2f
Signing by Device Secret
Attestation Certificate
Credential ID
Attestation Signature
Application Private Key Application Public Key
ECDSAP256
Application Public Key
Credential ID
App ID
Challenge
App ID Challenge
Client Data
https://www.w3.org/TR/webauthn/#fido-u2f-attestation
0 0 0 0Attestation Secret

23. Attestation Statement fido-u2f
Signing by Device Secret
Attestation Certificate
Credential ID
Attestation Signature
Application Private Key Application Public Key
ECDSAP256
Application Public Key
Credential ID
App ID
Challenge
App ID Challenge
Client Data
https://www.w3.org/TR/webauthn/#fido-u2f-attestation
0 0 0 0
Certificate:
Data:
Version: 3 (0x2)
Serial Number: 305582463 (0x1236d17f)
Signature Algorithm: sha256WithRSAEncryption
Issuer: CN = Yubico U2F Root CA Serial 457200631
Validity
Not Before: Aug 1 00:00:00 2014 GMT
Not After : Sep 4 00:00:00 2050 GMT
Subject: CN = Yubico U2F EE Serial 23925734103241087
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
Public-Key: (256 bit)
pub:
04:d3:65:a9:1e:5e:99:e0:d5:b4:39:c0:d9:af:bb:
87:f4:05:8e:47:dd:12:b1:44:ed:b1:4d:2b:33:f8:
d3:5c:15:13:e4:0d:79:f0:f9:99:ab:e2:36:71:95:
93:81:c9:dc:2b:07:85:8b:82:ac:63:47:62:04:cc:
f7:34:d6:ae:21
ASN1 OID: prime256v1
NIST CURVE: P-256
X509v3 extensions:
1.3.6.1.4.1.41482.2:
1.3.6.1.4.1.41482.1.5
1.3.6.1.4.1.45724.2.1.1:
...
Signature Algorithm: sha256WithRSAEncryption
22:1b:9b:b3:b2:72:24:f1:3e:be:a3:22:…
SHA1 Fingerprint=5C:5C:14:02:D0:9B:7D:3D:FE:C3:79:3F:C9:E6:33:49:57:81:46:C0
Attestation Secret
Signed by Yubico Root CA

24. Attestation Statement fido-u2f
Signing by Device Secret
Attestation Certificate
Credential ID
Attestation Signature
ECDSAP256
Application Public Key
Credential ID
App ID
Challenge
App ID Challenge
Client Data
0 0 0 0
Attestation Certificate
Response
Attestation Secret
Application Public Key

25. Attestation Statement fido-u2f
Signing by Device Secret
Attestation Certificate
Credential ID
ECDSAP256
Application Public Key
Credential ID
App ID
Challenge
App ID Challenge
Client Data
0 0 0 0
Response
Attestation Secret
Application Public Key
Attestation Signature Attestation Certificate

26. rpId, challenge, CredIDrpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
CredID
sign
Kpriv
RP
Hash of ClientData
{ type: “webauthn.get”
origin: “example.com”,
challenge: “xxxxxxxxx”,
tokenBinding: { status: …} }

27. Authentication re-generate private key
Generate Private Key from Credential ID
Credential ID
Attestation Certificate
App ID Challenge Credential ID
HASH MACNonce
App ID
HMAC
0 0 0 0Device Secret
Attestation Secret

28. Authentication re-generate private key
Generate Private Key from Credential ID
Credential ID
Attestation Certificate
App ID Challenge Credential ID
HASH MACNonce
Nonce
App ID
HMAC
0 0 0 0Device Secret
Attestation Secret

29. Authentication re-generate private key
Generate Private Key from Credential ID
Credential ID
Attestation Certificate
App ID Challenge Credential ID
HASH MACNonce
Nonce
App ID
Application Private Key
HMAC
0 0 0 0Device Secret
Attestation Secret

30. Authentication verify private key
Credential ID
Attestation Certificate
App ID Challenge Credential ID
Nonce
Application Private Key
HMAC
HASH MACNonce
0 0 0 0
Application Private Key
Device Secret
Attestation Secret

31. Authentication verify private key
Credential ID
Attestation Certificate
App ID Challenge Credential ID
Nonce
Application Private Key
HASH MAC
HMAC
HASH MACNonce
0 0 0 0Device Secret
Attestation Secret

32. Authentication verify private key
Check HMAC
Credential ID
Attestation Certificate
App ID Challenge Credential ID
Nonce
Application Private Key
HASH MAC
HMAC
HASH MACNonce
0 0 0 0Device Secret
Attestation Secret

33. Authentication signature
Attestation Certificate
App ID Challenge Credential ID
Application Private Key
ECDSA
App ID
Challenge
0 0 0 1
Attestation Secret

34. Authentication signature
Attestation Certificate
App ID Challenge Credential ID
Application Private Key
ECDSA
App ID
Challenge
0 0 0 1
0 0 0 1
Attestation Secret

35. Authentication signature
Attestation Certificate
App ID Challenge Credential ID
Application Private Key
ECDSA
App ID
Challenge
0 0 0 1
0 0 0 1
0 0 0 0 0 0 0 1
UP
Attestation Secret

36. Authentication signature
Attestation Certificate
App ID Challenge Credential ID
Application Private Key
ECDSA
App ID
Challenge
0 0 0 1
Signature
0 0 0 1
Attestation Secret

37. Authentication signature
Attestation Certificate
App ID Challenge Credential ID
Application Private Key
ECDSA
App ID
Challenge
0 0 0 1
Signature
0 0 0 1
0 0 0 1
Attestation Secret

38. using publicKey
Credential ID

39. What’s difference

41. Extensions
Resident Space Space
New Security Key (FIDO2 Spec)
Attestation CertificateAAGUID 0 0 0 0
******
PIN Support
Device Secret
Attestation Secret

42. Extensions
Resident Space Space
PIN Support
Attestation CertificateAAGUID 0 0 0 0
******
PIN Support
Device Secret
Attestation Secret

43. Extensions
Resident Space Space
Resident Key
Attestation CertificateAAGUID 0 0 0 0
******
PIN Support
Device Secret
Attestation Secret

44. Extensions
Resident Space Space
AAGUID
Attestation CertificateAAGUID 0 0 0 0
******
PIN Support
Device Secret
Attestation Secret

45. Attestation Secret
Device SecretExtensions
Resident Space Space
Support CTAP2 Extensions
(hmac-secret)
Attestation CertificateAAGUID 0 0 0 0
******
PIN Support
https://fidoalliance.org/specs/fido-v2.0-id-20180227/fido-client-to-authenticator-protocol-v2.0-id-20180227.html#sctn-hmac-secret-extension

46. Resident Key (FIDO2 Spec)
Attestation Certificate
Credential IDApp ID
User Info
Handle
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret

47. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
RP
Hash of ClientData
{ type: “webauthn.create”
origin: “example.com”,
challenge: “xxxxxxxxx”,
tokenBinding: { status: …} }

48. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info RP

49. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
authenticatorSelection: {
userVerification: “required“,
requireResidentKey: true,
authenticatorAttachment: “cross-platform”
}
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info
CTAP
RP

50. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
authenticatorSelection: {
userVerification: “required“,
requireResidentKey: true,
authenticatorAttachment: “cross-platform”
}
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info
CTAP
RP

51. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
authenticatorSelection: {
userVerification: “required“,
requireResidentKey: true,
authenticatorAttachment: “cross-platform”
}
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info
******
PIN
CTAP
RP

52. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
authenticatorSelection: {
userVerification: “required“,
requireResidentKey: true,
authenticatorAttachment: “cross-platform”
}
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info
rpId
User Info
CredID
******
PIN
CTAP ******
PIN
Store Credential of
www.example.com ?
RP

53. rpId, challengerpId, clientData
CredID, Public key CredID, Public key
authenticatorSelection: {
userVerification: “required“,
requireResidentKey: true,
authenticatorAttachment: “cross-platform”
}
AttestationAttestation
Registration
clientData
Check rpId
Generate Key-pair
for rpId
User Info,User Info
rpId
User Info
CredID
******
PIN
CTAP ******
PIN
Store Credential of
www.example.com ?
RP

54. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info WebAuthn spec!

55. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info
App ID
Challenge
RNG
Nonce

56. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info
Credential ID
Application Public Key
App ID
Challenge
RNG
Nonce

57. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info
Credential ID
Application Public Key
Credential ID
App ID User Info

58. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info
Credential ID
App ID User Info
必須なのは User Handle のみ

59. Registration with Resident Key
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0
Resident Space Space
Extensions Device Secret
Attestation Secret
User Info
Credential ID
App ID User Info
必須なのは User Handle のみ

60. rpId, challenge, CredIDrpId, clientData
CredID, sign CredID, clientData
Hash
{ origin: “example.com”,
challenge: “xxxxxxxxx” }
Authentication
CredID
CredID
sign
Kpriv
RP
Check rpId

61. CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
rpId
RP
rpId, challenge, CredID
Resident Key
PIN Support
rpId, clientData CredID
Optional

62. rpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
rpId
RP
rpId, challenge, CredID
[空にする]

63. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
rpId
RP
CTAP

64. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
rpId
RP
CTAP

65. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
rpId
RP
CTAP
User Info

66. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
User Info
User Info
login
rpId
RP
ユーザ情報が複数ある場合
はリスト表示される

67. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
user.id
userHandleUser Info
User Info
login
rpId
RP

68. rpId, challengerpId, clientData
CredID, sign CredID, clientData
Authentication
CredID
sign
Kpriv
User Info
CredID
******
PIN
user.id
userHandleUser Info
User Info
login
rpId
RP
userHandle
Kpub

69. Authentication
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0Extensions Device Secret
Attestation Secret
RP doesn’t send Credential ID
when id-less authentication
Credential ID
Resident Space Space
Credential ID
App ID User Info

70. Authentication
Attestation Certificate
App ID
AAGUID 0 0 0 0Extensions Device Secret
Attestation Secret
Authenticator list credentials for specific
AppID after User Info Verification(or
User Info Presence)
Challenge
Resident Space Space
Credential ID
App ID User Info
******

73. Origin bound
Stored Credentials

74. Authenticate
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0Extensions Device Secret
Attestation Secret
Credential ID Application Private Key
Resident Space Space
Credential ID
App ID User Info

75. Authenticate
Attestation Certificate
App ID Challenge
AAGUID 0 0 0 0Extensions Device Secret
Attestation Secret
Credential ID Application Private Key
Resident Space Space
Credential ID
App ID User Info

76. FIDO2
• Single factor Authentication
Credential Management API Support PublicKey Crypto
• 2nd Factor Authentication
WebAuthn Support both CTAP1 and CTAP2
• Multi-Factor: Passwordless + PIN or Biometric
CTAP2 Support User Info Verification

77. Thank you