Internet-Draft JOSE-COSE HPKE Cookbook March 2024
Steele Expires 3 September 2024 [Page]
Workgroup:
Javascript Object Signing and Encryption
Internet-Draft:
draft-steele-jose-cose-hpke-cookbook-00
Published:
Intended Status:
Informational
Expires:
Author:
O. Steele
Transmute

JOSE-COSE HPKE Cookbook

Abstract

This document contains a set of examples using JSON Object Signing and Encryption (JOSE), CBOR Object Signing and Encryption (COSE) and Hybrid Public Key Encryption (HPKE) to protect data. These examples are meant to coverage the edge cases of both JOSE and COSE, including different structures for single and multiple recipients, external additional authenticated data, and key derivation function (KDF) context binding.

About This Document

This note is to be removed before publishing as an RFC.

The latest revision of this draft can be found at https://OR13.github.io/draft-steele-jose-cose-hpke-cookbook/draft-steele-jose-cose-hpke-cookbook.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-steele-jose-cose-hpke-cookbook/.

Discussion of this document takes place on the Javascript Object Signing and Encryption Working Group mailing list (mailto:jose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/jose/. Subscribe at https://www.ietf.org/mailman/listinfo/jose/.

Source for this draft and an issue tracker can be found at https://github.com/OR13/draft-steele-jose-cose-hpke-cookbook.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 3 September 2024.

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Table of Contents

1. Introduction

This document is inspired by Examples of Protecting Content Using JSON Object Signing and Encryption (JOSE) [RFC7520].

JOSE support for HPKE is described in [I-D.draft-rha-jose-hpke-encrypt].

COSE support for HPKE is described in [I-D.draft-ietf-cose-hpke].

Both drafts are still work in progress.

The current set of examples are incomplete.

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

The term "JSON Web Key (JWK)" is defined in [RFC7517].

The term "COSE Key" is defined in [RFC9052].

The terms "JSON Web Encryption (JWE)", "Direct Key Agreement", "Key Agreement with Key Wrapping", "JWE Compact Serialization" and "General JWE JSON Serialization" are defined in [RFC7516].

The terms "Direct Encryption", and "Key Agreement with Key Wrap" are defined in [RFC9052].

The term "encapsulated key" is defined in [RFC9180].

This document does not define any new terms for JOSE or COSE.

3. Overview

Note that JSON (JavaScript Object Notation) and EDN (Extended Diagnostic Notation) may not exactly match the bytes provided for each example.

The hexadecimal encoded binary messages are the source of truth, the JSON and EDN examples are for readability.

NOTE: '' line wrapping per [RFC8792] in HTTP examples.

3.1. Private Key

This section provides private key representations that are used throught the following sections.

Public key representations for these keys are left as an excercise for the reader.

The keys in this section are restricted to a single algorithm in both JOSE and COSE: HPKE-Base-P256-SHA256-AES128GCM.

Additional algorithms and their private key representations may be provided in future versions of this draft.

3.1.1. application/jwk+json

This section provides a JSON Web Key for HPKE-Base-P256-SHA256-AES128GCM.

7b0a2020226b6964223a202275726e3a696574663a706172616d733a6f617574683a6a\
776b2d7468756d627072696e743a7368612d3235363a374a76784b756a755770596c4b\
49455f75726479543749457165345030635a33476d3163364554526c5130222c0a2020\
22616c67223a202248504b452d426173652d503235362d5348413235362d4145533132\
3847434d222c0a2020226b7479223a20224543222c0a202022637276223a2022502d32\
3536222c0a20202278223a2022646f37595f507a6f6c355f47326650686f50676f4f6f\
306b6b34632d386745386952345958715449596d34222c0a20202279223a2022616b6a\
4d396b56327a317057364b544c657148426b6d6d355332496d5f4f794f37526a527267\
6d66316455222c0a20202264223a20224b583649304a7554664430467231703243646c\
5239636f6e324851737759344673716a33437a533261704d220a7d
Figure 1: JSON Web Key Bytes 
{
  "kid": "urn:ietf:params:oauth:jwk-thumbprint:sha-256:7JvxKujuWpYlKIE_urdyT7IEqe4P0cZ3Gm1c6ETRlQ0",
  "alg": "HPKE-Base-P256-SHA256-AES128GCM",
  "kty": "EC",
  "crv": "P-256",
  "x": "do7Y_Pzol5_G2fPhoPgoOo0kk4c-8gE8iR4YXqTIYm4",
  "y": "akjM9kV2z1pW6KTLeqHBkmm5S2Im_OyO7RjRrgmf1dU",
  "d": "KX6I0JuTfD0Fr1p2CdlR9con2HQswY4Fsqj3CzS2apM"
}
Figure 2: JSON Web Key

3.1.2. application/cose-key

This section provides a COSE Key for HPKE-Base-P256-SHA256-AES128GCM.

a702784d75726e3a696574663a706172616d733a6f617574683a636b743a7368612d3\
235363a4b565f3339384668506158773761514d55595f4e5a497a7364416a7341544b\
7a73765a6f333058424e514d03182301022001215820768ed8fcfce8979fc6d9f3e1a\
0f8283a8d2493873ef2013c891e185ea4c8626e2258206a48ccf64576cf5a56e8a4cb\
7aa1c19269b94b6226fcec8eed18d1ae099fd5d5235820297e88d09b937c3d05af5a7\
609d951f5ca27d8742cc18e05b2a8f70b34b66a93
Figure 3: COSE Key Bytes 
{
  / kid / 2: "urn:ietf:params:oauth:ckt:sha-256:KV_398FhPaXw7aQMUY_NZIzsdAjsATKzsvZo30XBNQM",
  / alg: ES256 /  3: 35,
  / kty: EC2   /  1: 2,
  / crv: P-256 / -1: 1,
  / x / -2: h'768ed8fcfce8979fc6d9f3e1a0f8283a8d2493873ef2013c891e185ea4c8626e',
  / y / -3: h'6a48ccf64576cf5a56e8a4cb7aa1c19269b94b6226fcec8eed18d1ae099fd5d5',
  / d / -4: h'297e88d09b937c3d05af5a7609d951f5ca27d8742cc18e05b2a8f70b34b66a93'
}
Figure 4: COSE Key Diagnostic

3.2. Direct Encryption

JOSE and COSE HPKE both support a "Direct Encryption Mode", where HPKE encrypt a plaintext message and optional additional authenticated data directly to a recipient public key.

Note that HPKE Direct Encryption is not exactly the same as "Direct Encryption" as described in [RFC7516] and [RFC9052].

In this section we provide direct encryption examples to the private keys in the previous section.

⌛ My lungs taste the air of Time Blown past falling sands ⌛
Figure 5: Direct Encryption Message 
✨ It’s a dangerous business, Frodo, going out your door. ✨
Figure 6: Direct Encryption AAD

3.2.1. application/jose+json 

7b0a20202270726f746563746564223a202265794a68624763694f694a6b615849694c\
434a6c626d4d694f694a49554574464c554a6863325574554449314e69315453454579\
4e545974515556544d54493452304e4e496977695a584272496a7037496d7430655349\
36496b564c496977695a5773694f694a43526d466a593073795546687859586c615130\
3078526b68366245307a4d6a46584e3268334d6a56485557677751544974616e426163\
553479516e564654575253595746464d7a5a7856306b315a5446766346687161474e4f\
56575234643164435a334e5a596b4e7056456f7a65453579537a5169665830222c0a20\
2022616164223a20223470796f49456c30346f435a6379426849475268626d646c636d\
39316379426964584e70626d567a63797767526e4a765a473873494764766157356e49\
47393164434235623356794947527662334975494f4b637141222c0a20202263697068\
657274657874223a20226449326b4b2d6634787634446d45647848706e4f474130732d\
695f4338735059444d3674664a456f6a6c6b5351355865586f41755151566d587a6479\
754c6255476a69416a6967744e3455414a556b556f2d55673430695771435632544662\
326e586579566436456167220a7d
Figure 7: JOSE Direct Encryption Bytes 
{
  "protected": "eyJhbGciOiJkaXIiLCJlbmMiOiJIUEtFLUJhc2UtUDI1Ni1TSEEyNTYtQUVTMTI4R0NNIiwiZXBrIjp7Imt0eSI6IkVLIiwiZWsiOiJCRmFjY0syUFhxYXlaQ00xRkh6bE0zMjFXN2h3MjVHUWgwQTItanBacU4yQnVFTWRSYWFFMzZxV0k1ZTFvcFhqaGNOVWR4d1dCZ3NZYkNpVEozeE5ySzQifX0",
  "aad": "4pyoIEl04oCZcyBhIGRhbmdlcm91cyBidXNpbmVzcywgRnJvZG8sIGdvaW5nIG91dCB5b3VyIGRvb3IuIOKcqA",
  "ciphertext": "dI2kK-f4xv4DmEdxHpnOGA0s-i_C8sPYDM6tfJEojlkSQ5XeXoAuQQVmXzdyuLbUGjiAjigtN4UAJUkUo-Ug40iWqCV2TFb2nXeyVd6Eag"
}
Figure 8: JOSE Direct Encryption 
{
  "alg": "dir",
  "enc": "HPKE-Base-P256-SHA256-AES128GCM",
  "epk": {
    "kty": "EK",
    "ek": "BFaccK2PXqayZCM1FHzlM321W7hw25GQh0A2-jpZqN2BuEMdRaaE36qWI5e1opXjhcNUdxwWBgsYbCiTJ3xNrK4"
  }
}
Figure 9: JOSE Direct Encryption Decoded Protected Header

3.2.2. application/cose 

d08344a1011823a204784d75726e3a696574663a706172616d733a6f617574683a636\
b743a7368612d3235363a4b565f3339384668506158773761514d55595f4e5a497a73\
64416a7341544b7a73765a6f333058424e514d235841048024424acb8a77edfbc461b\
c4947e5d3ac3e5d31bc5f8a9fe71d0e4ef79f4b27943418a3817a14f6de06b43b98ce\
ac551d4cf47e888293a271a9117db7abf19a584f693181d2479aca080d3e71ce37624\
10665415cab2b831cac4fef97105cdec3b3a71de61019ceb0431d1637de54bab7f855\
fe8bae7bd9ba5cc12a20d458baf08f4cf861da4a831964745eceb97f3bbf
Figure 10: COSE Direct Encryption Bytes 
16([ / Single Recipient Encryption /
  h'a1011823', / Protected Header
  { / Unprotected Header /
    / kid / 4: "urn:ietf:params:oauth:ckt:sha-256:KV_398FhPaXw7aQMUY_NZIzsdAjsATKzsvZo30XBNQM",
    / ek / -4: h'048024424acb8a77edfbc461bc4947e5d3ac3e5d31bc5f8a9fe71d0e4ef79f4b27943418a3817a14f6de06b43b98ceac551d4cf47e888293a271a9117db7abf19a'
  },
  h'693181d2479aca080d3e71ce3762410665415cab2b831cac4fef97105cdec3b3a71de61019ceb0431d1637de54bab7f855fe8bae7bd9ba5cc12a20d458baf08f4cf861da4a831964745eceb97f3bbf'
])
Figure 11: COSE Direct Encryption Diagnostic

Note that JOSE and COSE transport the encapsulated key "ek" differently.

3.3. Key Encryption

JOSE and COSE HPKE both support a "Key Encryption Mode", where HPKE encrypt a content encryption key to a recipient public key, and a plaintext message and optional additional authenticated with the content encryption key.

Note that HPKE Key Encryption Mode is not exactly the same as "Key Agreement with Key Wrap" as described in [RFC7516] and [RFC9052].

In this section we provide direct encryption examples to the private keys in the previous section.

⌛ My lungs taste the air of Time Blown past falling sands ⌛
Figure 12: Key Encryption Message 
✨ It’s a dangerous business, Frodo, going out your door. ✨
Figure 13: Key Encryption AAD

3.3.1. application/jose+json 

7b0a20202270726f746563746564223a202265794a6c626d4d694f694a424d5449345\
2304e4e496977695a584272496a7037496d743065534936496b564c496977695a5773\
694f694a43526b524862456f77533045774e3364305a454668543270445644557a564\
5314c546e4266595578504f4467794d30525954314d32533370525557396e63555256\
576a6832515768335355396e513035345a574d78545735575345563361556c4d4d6e7\
07963334a50526d786b5255746865453069665830222c0a202022656e637279707465\
645f6b6579223a202274774d563367697a4c7a5f74674455425831564b2d505a6a6b2\
d503737415845745442445a44444c423973222c0a2020226976223a20223178716256\
53586e6654524253675947222c0a20202263697068657274657874223a20225a5f546\
6517a684643355a2d394a2d4f6b41676632784535364d75584b5f6b69793569594935\
4a444e6c76474e794338534856754a7956346e5a6e7867396e624953525a7561477a7\
8594971355a745469614434222c0a202022746167223a202259696844336762695a69\
47624458662d5851434d7241222c0a202022616164223a20223470796f49456c30346\
f435a6379426849475268626d646c636d39316379426964584e70626d567a63797767\
526e4a765a473873494764766157356e4947393164434235623356794947527662334\
975494f4b637141220a7d
Figure 14: JOSE Key Encryption Bytes 
{
  "protected": "eyJlbmMiOiJBMTI4R0NNIiwiZXBrIjp7Imt0eSI6IkVLIiwiZWsiOiJCRkRHbEowS0EwN3d0ZEFhT2pDVDUzVE1LTnBfYUxPODgyM0RYT1M2S3pRUW9ncURVWjh2QWh3SU9nQ054ZWMxTW5WSEV3aUlMMnpyc3JPRmxkRUtheE0ifX0",
  "encrypted_key": "twMV3gizLz_tgDUBX1VK-PZjk-P77AXEtTBDZDDLB9s",
  "iv": "1xqbVSXnfTRBSgYG",
  "ciphertext": "Z_TfQzhFC5Z-9J-OkAgf2xE56MuXK_kiy5iYI5JDNlvGNyC8SHVuJyV4nZnxg9nbISRZuaGzxYIq5ZtTiaD4",
  "tag": "YihD3gbiZiGbDXf-XQCMrA",
  "aad": "4pyoIEl04oCZcyBhIGRhbmdlcm91cyBidXNpbmVzcywgRnJvZG8sIGdvaW5nIG91dCB5b3VyIGRvb3IuIOKcqA"
}
Figure 15: JOSE Key Encryption JSON 
{
  "enc": "A128GCM",
  "epk": {
    "kty": "EK",
    "ek": "BFDGlJ0KA07wtdAaOjCT53TMKNp_aLO8823DXOS6KzQQogqDUZ8vAhwIOgCNxec1MnVHEwiIL2zrsrOFldEKaxM"
  }
}
Figure 16: JOSE Key Encryption Decoded Protected Header

Note that the ephemeral public key (epk) is present in the protected header due to there only being a single recipient for this message.

3.3.2. application/cose 

d8608443a10101a10550335552a987fd47dc85016ccc760bb541584fa0d7678a14400\
1cc48d1ff514545df9e0da6b696a8ed3bceb529b78ba86c26bef93767d07b0111a48e\
38dd79bfe9c351d6508ec2805b30ea16f6b46156e3ba9cffc11a39c311554970c7bda\
a40d4c1818344a1011823a204784d75726e3a696574663a706172616d733a6f617574\
683a636b743a7368612d3235363a4b565f3339384668506158773761514d55595f4e5\
a497a7364416a7341544b7a73765a6f333058424e514d235841044e733517b62d8cf9\
00d3d84606f8907bea0e3481c123359197782f0869b36c0efe13e76ae4740bcaf2f7a\
f1e03523efe1b98dc4b81a94d45d9dfea583ef14e0f582000871c2c5f6a8b73aab9cf\
df26953dc026036f00a08b61d903dd4a72e9c01229
Figure 17: COSE Key Encryption Bytes 
96([ / Multiple Recipient Encrypted Message /
  h'a10101',  / Protected Header /
  {
    / IV / 5: h'335552a987fd47dc85016ccc760bb541'
  },
  / Ciphertext / h'a0d7678a144001cc48d1ff514545df9e0da6b696a8ed3bceb529b78ba86c26bef93767d07b0111a48e38dd79bfe9c351d6508ec2805b30ea16f6b46156e3ba9cffc11a39c311554970c7bdaa40d4c1',
  [ / Recipients /
    [ / Recipient 0 /
      h'a1011823',  / Recipient Protected Header /
      { / Recipient Unprotected Header /
        / kid /  4: "urn:ietf:params:oauth:ckt:sha-256:KV_398FhPaXw7aQMUY_NZIzsdAjsATKzsvZo30XBNQM",
        / ek  / -4: h'044e733517b62d8cf900d3d84606f8907bea0e3481c123359197782f0869b36c0efe13e76ae4740bcaf2f7af1e03523efe1b98dc4b81a94d45d9dfea583ef14e0f'
      },
      / encrypted key / h'00871c2c5f6a8b73aab9cfdf26953dc026036f00a08b61d903dd4a72e9c01229'
    ]
  ]
])
Figure 18: COSE Key Encryption Diagnostic

4. Security Considerations

TODO Security

5. IANA Considerations

This document has no IANA actions.

6. References

6.1. Normative References

[I-D.draft-ietf-cose-hpke]
Tschofenig, H., Steele, O., Daisuke, A., and L. Lundblade, "Use of Hybrid Public-Key Encryption (HPKE) with CBOR Object Signing and Encryption (COSE)", Work in Progress, Internet-Draft, draft-ietf-cose-hpke-07, , <https://datatracker.ietf.org/doc/html/draft-ietf-cose-hpke-07>.
[I-D.draft-rha-jose-hpke-encrypt]
Reddy.K, T., Tschofenig, H., Banerjee, A., Steele, O., and M. B. Jones, "Use of Hybrid Public-Key Encryption (HPKE) with Javascript Object Signing and Encryption (JOSE)", Work in Progress, Internet-Draft, draft-rha-jose-hpke-encrypt-05, , <https://datatracker.ietf.org/doc/html/draft-rha-jose-hpke-encrypt-05>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.

6.2. Informative References

[RFC7516]
Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)", RFC 7516, DOI 10.17487/RFC7516, , <https://www.rfc-editor.org/rfc/rfc7516>.
[RFC7517]
Jones, M., "JSON Web Key (JWK)", RFC 7517, DOI 10.17487/RFC7517, , <https://www.rfc-editor.org/rfc/rfc7517>.
[RFC7520]
Miller, M., "Examples of Protecting Content Using JSON Object Signing and Encryption (JOSE)", RFC 7520, DOI 10.17487/RFC7520, , <https://www.rfc-editor.org/rfc/rfc7520>.
[RFC8792]
Watsen, K., Auerswald, E., Farrel, A., and Q. Wu, "Handling Long Lines in Content of Internet-Drafts and RFCs", RFC 8792, DOI 10.17487/RFC8792, , <https://www.rfc-editor.org/rfc/rfc8792>.
[RFC9052]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", STD 96, RFC 9052, DOI 10.17487/RFC9052, , <https://www.rfc-editor.org/rfc/rfc9052>.
[RFC9180]
Barnes, R., Bhargavan, K., Lipp, B., and C. Wood, "Hybrid Public Key Encryption", RFC 9180, DOI 10.17487/RFC9180, , <https://www.rfc-editor.org/rfc/rfc9180>.

Acknowledgments

TODO acknowledge.

Author's Address

Orie Steele
Transmute