--- 1/draft-ietf-httpbis-encryption-encoding-04.txt 2016-12-21 21:13:17.327451781 -0800 +++ 2/draft-ietf-httpbis-encryption-encoding-05.txt 2016-12-21 21:13:17.359452538 -0800 @@ -1,18 +1,18 @@ HTTP Working Group M. Thomson Internet-Draft Mozilla -Intended status: Standards Track October 31, 2016 -Expires: May 4, 2017 +Intended status: Standards Track December 21, 2016 +Expires: June 24, 2017 Encrypted Content-Encoding for HTTP - draft-ietf-httpbis-encryption-encoding-04 + draft-ietf-httpbis-encryption-encoding-05 Abstract This memo introduces a content coding for HTTP that allows message payloads to be encrypted. Note to Readers Discussion of this draft takes place on the HTTP working group mailing list (ietf-http-wg@w3.org), which is archived at @@ -30,21 +30,21 @@ 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 http://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 May 4, 2017. + This Internet-Draft will expire on June 24, 2017. Copyright Notice Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -54,44 +54,39 @@ the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 2. The "aes128gcm" HTTP Content Coding . . . . . . . . . . . . . 3 2.1. Encryption Content Coding Header . . . . . . . . . . . . 5 2.2. Content Encryption Key Derivation . . . . . . . . . . . . 6 - 2.3. Nonce Derivation . . . . . . . . . . . . . . . . . . . . 7 - 3. Crypto-Key Header Field . . . . . . . . . . . . . . . . . . . 7 - 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 4.1. Encryption of a Response . . . . . . . . . . . . . . . . 8 - 4.2. Encryption with Multiple Records . . . . . . . . . . . . 9 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 - 5.1. Key and Nonce Reuse . . . . . . . . . . . . . . . . . . . 10 - 5.2. Data Encryption Limits . . . . . . . . . . . . . . . . . 10 - 5.3. Content Integrity . . . . . . . . . . . . . . . . . . . . 10 - 5.4. Leaking Information in Headers . . . . . . . . . . . . . 11 - 5.5. Poisoning Storage . . . . . . . . . . . . . . . . . . . . 11 - 5.6. Sizing and Timing Attacks . . . . . . . . . . . . . . . . 12 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 - 6.1. The "aes128gcm" HTTP Content Coding . . . . . . . . . . . 12 - 6.2. Crypto-Key Header Field . . . . . . . . . . . . . . . . . 12 - 6.3. The HTTP Crypto-Key Parameter Registry . . . . . . . . . 12 - 6.3.1. keyid . . . . . . . . . . . . . . . . . . . . . . . . 13 - 6.3.2. aes128gcm . . . . . . . . . . . . . . . . . . . . . . 13 - 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 - 7.1. Normative References . . . . . . . . . . . . . . . . . . 13 - 7.2. Informative References . . . . . . . . . . . . . . . . . 14 - Appendix A. JWE Mapping . . . . . . . . . . . . . . . . . . . . 15 - Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 16 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 16 + 2.3. Nonce Derivation . . . . . . . . . . . . . . . . . . . . 6 + 3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 7 + 3.1. Encryption of a Response . . . . . . . . . . . . . . . . 7 + 3.2. Encryption with Multiple Records . . . . . . . . . . . . 8 + 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 + 4.1. Key and Nonce Reuse . . . . . . . . . . . . . . . . . . . 9 + 4.2. Data Encryption Limits . . . . . . . . . . . . . . . . . 9 + 4.3. Content Integrity . . . . . . . . . . . . . . . . . . . . 9 + 4.4. Leaking Information in Headers . . . . . . . . . . . . . 10 + 4.5. Poisoning Storage . . . . . . . . . . . . . . . . . . . . 10 + 4.6. Sizing and Timing Attacks . . . . . . . . . . . . . . . . 11 + 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 + 5.1. The "aes128gcm" HTTP Content Coding . . . . . . . . . . . 11 + 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 + 6.1. Normative References . . . . . . . . . . . . . . . . . . 11 + 6.2. Informative References . . . . . . . . . . . . . . . . . 12 + Appendix A. JWE Mapping . . . . . . . . . . . . . . . . . . . . 13 + Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 14 + Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction It is sometimes desirable to encrypt the contents of a HTTP message (request or response) so that when the payload is stored (e.g., with a HTTP PUT), only someone with the appropriate key can read it. For example, it might be necessary to store a file on a server without exposing its contents to that server. Furthermore, that same file could be replicated to other servers (to make it more resistant @@ -112,107 +107,104 @@ [RFC5116]. To the extent that message-based encryption formats use the same primitives, the format can be considered as sequence of encrypted messages with a particular profile. For instance, Appendix A explains how the format is congruent with a sequence of JSON Web Encryption [RFC7516] values with a fixed header. This mechanism is likely only a small part of a larger design that uses content encryption. How clients and servers acquire and - identify keys will depend on the use case. Though a complete key - management system is not described, this document defines an Crypto- - Key header field that can be used to convey keying material. + identify keys will depend on the use case. In particular, a key + management system is not described. 1.1. Notational Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Base64url encoding is defined in Section 2 of [RFC7515]. 2. The "aes128gcm" HTTP Content Coding The "aes128gcm" HTTP content coding indicates that a payload has been encrypted using Advanced Encryption Standard (AES) in Galois/Counter Mode (GCM) as identified as AEAD_AES_128_GCM in [RFC5116], Section 5.1. The AEAD_AES_128_GCM algorithm uses a 128 bit content encryption key. - Using this content coding requires knowledge of a key. The Crypto- - Key header field (Section 3) can be included to describe how the - content encryption key is derived or retrieved. Keys might be - provided in messages that are separate from those with encrypted - content using Crypto-Key, or provided through external mechanisms. + Using this content coding requires knowledge of a key. How this key + is acquired is not defined in this document. The "aes128gcm" content coding uses a single fixed set of encryption primitives. Cipher suite agility is achieved by defining a new content coding scheme. This ensures that only the HTTP Accept- Encoding header field is necessary to negotiate the use of encryption. The "aes128gcm" content coding uses a fixed record size. The final encoding consists of a header (see Section 2.1), zero or more fixed size encrypted records, and a partial record. The partial record MUST be shorter than the fixed record size. + The record size determines the length of each portion of plaintext + that is enciphered, with the exception of the final record, which is + necessarily smaller. The record size ("rs") is included in the + content coding header (see Section 2.1). + +-----------+ content is rs octets minus padding | data | of between 2 and 65537 octets; +-----------+ the last record is smaller | v +-----+-----------+ add padding to get rs octets; | pad | data | the last record contains +-----+-----------+ up to rs minus 1 octets | v +--------------------+ encrypt with AEAD_AES_128_GCM; | ciphertext | final size is rs plus 16 octets +--------------------+ the last record is smaller - The record size determines the length of each portion of plaintext - that is enciphered, with the exception of the final record, which is - necessarily smaller. The record size ("rs") is included in the - content coding header (see Section 2.1). - AEAD_AES_128_GCM produces ciphertext 16 octets longer than its input plaintext. Therefore, the length of each enciphered record other than the last is equal to the value of the "rs" parameter plus 16 - octets. To prevent an attacker from truncating a stream, an encoder - MUST append a record that contains only padding and is smaller than - the full record size if the final record ends on a record boundary. - A receiver MUST fail to decrypt if the final record ciphertext is - less than 18 octets in size or equal to the record size plus 16 (that - is, the size of a full encrypted record). Valid records always - contain at least two octets of padding and a 16 octet authentication - tag. + octets. If the final record ends on a record boundary, the encoder + MUST append a record that contains contains only padding and is + smaller than the full record size. A receiver MUST fail to decrypt + if the final record ciphertext is less than 18 octets in size or + equal to the record size plus 16 (that is, the size of a full + encrypted record). Valid records always contain at least two octets + of padding and a 16 octet authentication tag. - Each record contains between 2 and 65537 octets of padding, inserted - into a record before the enciphered content. Padding consists of a - two octet unsigned integer in network byte order, followed that - number of zero-valued octets. A receiver MUST fail to decrypt if any - padding octet other than the first two are non-zero, or a record has - more padding than the record size can accommodate. + Each record contains a 2 octet padding length field and between 0 and + 65535 octets of padding, inserted into a record before the enciphered + content. The padding length is a two octet unsigned integer in + network byte order; padding is that number of zero-valued octets. A + receiver MUST fail to decrypt if any padding octet is non-zero, or a + record has more padding than the record size can accommodate. The nonce for each record is a 96-bit value constructed from the record sequence number and the input keying material. Nonce derivation is covered in Section 2.3. The additional data passed to each invocation of AEAD_AES_128_GCM is a zero-length octet sequence. A consequence of this record structure is that range requests [RFC7233] and random access to encrypted payload bodies are possible at the granularity of the record size. Partial records at the ends of a range cannot be decrypted. Thus, it is best if range requests - start and end on record boundaries. + start and end on record boundaries. Note however that random access + to specific parts of encrypted data could be confounded by the + presence of padding. Selecting the record size most appropriate for a given situation requires a trade-off. A smaller record size allows decrypted octets to be released more rapidly, which can be appropriate for applications that depend on responsiveness. Smaller records also reduce the additional data required if random access into the ciphertext is needed. Applications that depend on being able to pad by arbitrary amounts cannot increase the record size beyond 65537 octets. @@ -237,41 +229,37 @@ every application of the content coding ensures that content encryption key reuse is highly unlikely. rs: The "rs" or record size parameter contains an unsigned 32-bit integer in network byte order that describes the record size in octets. Note that it is therefore impossible to exceed the 2^36-31 limit on plaintext input to AEAD_AES_128_GCM. Values smaller than 3 are invalid. keyid: The "keyid" parameter can be used to identify the keying - material that is used. When the Crypto-Key header field is used, - the "keyid" identifies a matching value in that field. The - "keyid" parameter MUST be used if keying material included in an - Crypto-Key header field is needed to derive the content encryption - key. The "keyid" parameter can also be used to identify keys in - an application-specific fashion. + material that is used. Recipients that receive a message are + expected to know how to retrieve keys; the "keyid" parameter might + be input to that process. 2.2. Content Encryption Key Derivation In order to allow the reuse of keying material for multiple different HTTP messages, a content encryption key is derived for each message. - The content encryption key is derived from the decoded value of the - "salt" parameter using the HMAC-based key derivation function (HKDF) - described in [RFC5869] using the SHA-256 hash algorithm [FIPS180-4]. + The content encryption key is derived from the "salt" parameter using + the HMAC-based key derivation function (HKDF) described in [RFC5869] + using the SHA-256 hash algorithm [FIPS180-4]. The value of the "salt" parameter is the salt input to HKDF function. The keying material identified by the "keyid" parameter is the input - keying material (IKM) to HKDF. Input keying material can either be - prearranged, or can be described using the Crypto-Key header field - (Section 3). The extract phase of HKDF therefore produces a - pseudorandom key (PRK) as follows: + keying material (IKM) to HKDF. Input keying material is expected to + be provided to recipients separately. The extract phase of HKDF + therefore produces a pseudorandom key (PRK) as follows: PRK = HMAC-SHA-256(salt, IKM) The info parameter to HKDF is set to the ASCII-encoded string "Content-Encoding: aes128gcm" and a single zero octet: cek_info = "Content-Encoding: aes128gcm" || 0x00 Note: Concatenation of octet sequences is represented by the "||" operator. @@ -305,163 +293,132 @@ at zero. Thus, the final nonce for each record is a 12 octet value: NONCE = HMAC-SHA-256(PRK, nonce_info || 0x01) XOR SEQ This nonce construction prevents removal or reordering of records. However, it permits truncation of the tail of the sequence (see Section 2 for how this is avoided). -3. Crypto-Key Header Field - - A Crypto-Key header field can be used to describe the input keying - material used by the "aes128gcm" content coding. - - Ordinarily, this header field will not appear in the same message as - the encrypted content. Including the encryption key with the - encrypted payload reduces the value of using encryption to a somewhat - complicated checksum. However, the Crypto-Key header field could be - used in one message to provision keys for other messages. - - The Crypto-Key header field uses the extended ABNF syntax defined in - Section 1.2 of [RFC7230] and the "parameter" and "OWS" rules from - [RFC7231]. - - Crypto-Key = #crypto-key-params - crypto-key-params = [ parameter *( OWS ";" OWS parameter ) ] - - keyid: The "keyid" parameter corresponds to the "keyid" parameter in - the content coding. - - aes128gcm: The "aes128gcm" parameter contains the base64url-encoded - octets [RFC7515] of the input keying material for the "aes128gcm" - content coding. - - Crypto-Key header field values with multiple instances of the same - parameter name in a single crypto-key-params production are invalid. - - The input keying material used by the key derivation (see - Section 2.2) can be determined based on the information in the - Crypto-Key header field. - - The value or values provided in the Crypto-Key header field is valid - only for the current HTTP message unless additional information - indicates a greater scope. - - Alternative methods for determining input keying material MAY be - defined by specifications that use this content coding. This - document only defines the use of the "aes128gcm" parameter which - describes an explicit key. - - The "aes128gcm" parameter MUST decode to at least 16 octets in order - to be used as input keying material for "aes128gcm" content coding. - -4. Examples +3. Examples This section shows a few examples of the encrypted content coding. Note: All binary values in the examples in this section use base64url encoding [RFC7515]. This includes the bodies of requests. Whitespace and line wrapping is added to fit formatting constraints. -4.1. Encryption of a Response +3.1. Encryption of a Response - Here, a successful HTTP GET response has been encrypted using input - keying material that is identified by the string "a1". + Here, a successful HTTP GET response has been encrypted. This uses a + record size of 4096 and no padding (just the 2 octet padding length), + so only a partial record is present. The input keying material is + identified by an empty string (that is, the "keyid" field in the + header is zero octets in length). The encrypted data in this example is the UTF-8 encoded string "I am - the walrus". The input keying material is included in the Crypto-Key - header field. The content body contains a single record only and is - shown here using base64url encoding for presentation reasons. + the walrus". The input keying material is the value + "B33e_VeFrOyIHwFTIfmesA" (in base64url). The content body contains a + single record and is shown here using base64url encoding for + presentation reasons. HTTP/1.1 200 OK Content-Type: application/octet-stream - Content-Length: 33 + Content-Length: 54 Content-Encoding: aes128gcm - Crypto-Key: aes128gcm=B33e_VeFrOyIHwFTIfmesA - 9Y1iaZMzICC05DO3y8dWiAAAopoAzpM9l8LHdpDaO9C-UvT4kttTI_edSsHv1o5b - lWZ5mBYL + sJvlboCWzB5jr8hI_q9cOQAAEAAANSmxkSVa0-MiNNuF77YHSs-iwaNe_OK0qfmO + c7NT5WSW Note that the media type has been changed to "application/octet- stream" to avoid exposing information about the content. Alternatively (and equivalently), the Content-Type header field can be omitted. -4.2. Encryption with Multiple Records + Intermediate values for this example (all shown in base64): - This example shows the same encrypted message, but split into records - of 10 octets each. The first record includes a single additional - octet of padding, which causes the end of the content to align with a + salt (from header) = sJvlboCWzB5jr8hI_q9cOQ + PRK = MLAQxt_DHjM15cdlyU1oUnjq7TFlzToGTkdRmvvxVBw + CEK = v31u7VGV3soO3wNaMaIdhg + NONCE = XOaygzko98zjUFTJ + plaintext = AABJIGFtIHRoZSB3YWxydXM + +3.2. Encryption with Multiple Records + + This example shows the same message with input keying material of + "BO3ZVPxUlnLORbVGMpbT1Q". In this example, the plaintext is split + into records of 10 octets each (that is, the "rs" field in the header + is 10). The first record includes a single octet of padding. This + means that there are 7 octets of message in the first record, and 8 + in the second. This causes the end of the content to align with a record boundary, forcing the creation of a third record that contains - only padding. + only two octets of the padding length. HTTP/1.1 200 OK - Content-Length: 70 + Content-Length: 93 Content-Encoding: aes128gcm - Crypto-Key: keyid="a1"; aes128gcm="BO3ZVPxUlnLORbVGMpbT1Q" - _lgOPHdbKmIaLnZC7_8huQAAAAoCYTGkQWUSYylMKzMduBHDCFDwL2oODx8nkh0n - uOTNrh48DaWSm02DiQPzQAOGe6xRAeBj588hH6jQRTh_szFRS2Nwx9Aeuiic + uNCkWiNYzKTnBN9ji3-qWAAAAAoCYTGHOqYFz-0in3dpb-VE2GfBngkaPy6bZus_ + qLF79s6zQyTSsA0iLOKyd3JqVIwprNzVatRCWZGUx_qsFbJBCQu62RqQuR2d -5. Security Considerations +4. Security Considerations This mechanism assumes the presence of a key management framework that is used to manage the distribution of keys between valid senders and receivers. Defining key management is part of composing this mechanism into a larger application, protocol, or framework. Implementation of cryptography - and key management in particular - can be difficult. For instance, implementations need to account for the potential for exposing keying material on side channels, such as might be exposed by the time it takes to perform a given operation. The requirements for a good implementation of cryptographic algorithms can change over time. -5.1. Key and Nonce Reuse +4.1. Key and Nonce Reuse Encrypting different plaintext with the same content encryption key and nonce in AES-GCM is not safe [RFC5116]. The scheme defined here uses a fixed progression of nonce values. Thus, a new content encryption key is needed for every application of the content coding. Since input keying material can be reused, a unique "salt" parameter is needed to ensure a content encryption key is not reused. If a content encryption key is reused - that is, if input keying material and salt are reused - this could expose the plaintext and the authentication key, nullifying the protection offered by encryption. Thus, if the same input keying material is reused, then the salt parameter MUST be unique each time. This ensures that the content encryption key is not reused. An implementation SHOULD generate a random salt parameter for every message; a counter could achieve the same result. -5.2. Data Encryption Limits +4.2. Data Encryption Limits There are limits to the data that AEAD_AES_128_GCM can encipher. The maximum value for the record size is limited by the size of the "rs" field in the header (see Section 2.1), which ensures that the 2^36-31 limit for a single application of AEAD_AES_128_GCM is not reached [RFC5116]. In order to preserve a 2^-40 probability of indistinguishability under chosen plaintext attack (IND-CPA), the total amount of plaintext that can be enciphered MUST be less than 2^44.5 blocks of 16 octets [AEBounds]. If rs is a multiple of 16 octets, this means 398 terabytes can be - encrypted safely, including padding. However, if the record size is - not a multiple of 16 octets, the total amount of data that can be - safely encrypted is reduced proportionally. The worst case is a - record size of 3 octets, for which at most 74 terabytes of plaintext - can be encrypted, of which at least two-thirds is padding. + encrypted safely, including padding and overhead. However, if the + record size is not a multiple of 16 octets, the total amount of data + that can be safely encrypted is reduced proportionally. The worst + case is a record size of 3 octets, for which at most 74 terabytes of + plaintext can be encrypted, of which at least two-thirds is padding. -5.3. Content Integrity +4.3. Content Integrity This mechanism only provides content origin authentication. The authentication tag only ensures that an entity with access to the content encryption key produced the encrypted data. Any entity with the content encryption key can therefore produce content that will be accepted as valid. This includes all recipients of the same HTTP message. Furthermore, any entity that is able to modify both the Encryption @@ -459,26 +416,25 @@ This mechanism only provides content origin authentication. The authentication tag only ensures that an entity with access to the content encryption key produced the encrypted data. Any entity with the content encryption key can therefore produce content that will be accepted as valid. This includes all recipients of the same HTTP message. Furthermore, any entity that is able to modify both the Encryption header field and the HTTP message body can replace the contents. - Without the content encryption key or the input keying material, modifications to or replacement of parts of a payload body are not possible. -5.4. Leaking Information in Headers +4.4. Leaking Information in Headers Because only the payload body is encrypted, information exposed in header fields is visible to anyone who can read the HTTP message. This could expose side-channel information. For example, the Content-Type header field can leak information about the payload body. There are a number of strategies available to mitigate this threat, depending upon the application's threat model and the users' @@ -494,152 +450,104 @@ in other representations, etc.), omit the relevant headers, and/ or normalize them. In the case of Content-Type, this could be accomplished by always sending Content-Type: application/octet- stream (the most generic media type), or no Content-Type at all. 3. If it is considered sensitive information and it is not possible to convey it elsewhere, encapsulate the HTTP message using the application/http media type (Section 8.3.2 of [RFC7230]), encrypting that as the payload of the "outer" message. -5.5. Poisoning Storage +4.5. Poisoning Storage This mechanism only offers encryption of content; it does not perform authentication or authorization, which still needs to be performed (e.g., by HTTP authentication [RFC7235]). This is especially relevant when a HTTP PUT request is accepted by a server; if the request is unauthenticated, it becomes possible for a third party to deny service and/or poison the store. -5.6. Sizing and Timing Attacks +4.6. Sizing and Timing Attacks Applications using this mechanism need to be aware that the size of encrypted messages, as well as their timing, HTTP methods, URIs and so on, may leak sensitive information. This risk can be mitigated through the use of the padding that this mechanism provides. Alternatively, splitting up content into segments and storing the separately might reduce exposure. HTTP/2 [RFC7540] combined with TLS [RFC5246] might be used to hide the size of individual messages. -6. IANA Considerations + Developing a padding strategy is difficult. A good padding strategy + can depend on context. Common strategies include padding to a small + set of fixed lengths, padding to multiples of a values, or padding to + powers of 2. Even a good strategy can still cause size information + to leak if processing activity of a recipient can be observed. This + is especially true if the trailing records of a message contain only + padding. Distributing non-padding data is recommended to avoid + leaking size information. -6.1. The "aes128gcm" HTTP Content Coding +5. IANA Considerations + +5.1. The "aes128gcm" HTTP Content Coding This memo registers the "aes128gcm" HTTP content coding in the HTTP Content Codings Registry, as detailed in Section 2. o Name: aes128gcm o Description: AES-GCM encryption with a 128-bit content encryption key o Reference: this specification -6.2. Crypto-Key Header Field - - This memo registers the "Crypto-Key" HTTP header field in the - Permanent Message Header Registry, as detailed in Section 3. - - o Field name: Crypto-Key - - o Protocol: HTTP - - o Status: Standard - - o Reference: this specification - - o Notes: - -6.3. The HTTP Crypto-Key Parameter Registry - - This memo establishes a registry for parameters used by the "Crypto- - Key" header field under the "Hypertext Transfer Protocol (HTTP) - Parameters" grouping. The "Hypertext Transfer Protocol (HTTP) - Crypto-Key Parameters" operates under an "Specification Required" - policy [RFC5226]. - - Entries in this registry are expected to include the following - information: - - o Parameter Name: The name of the parameter. - - o Purpose: A brief description of the purpose of the parameter. - - o Reference: A reference to a specification that defines the - semantics of the parameter. - - The initial contents of this registry are: - -6.3.1. keyid - - o Parameter Name: keyid - - o Purpose: Identify the key that is in use. - - o Reference: this document - -6.3.2. aes128gcm - - o Parameter Name: aes128gcm - - o Purpose: Provide an explicit input keying material value for the - aes128gcm content coding. - - o Reference: this document - -7. References +6. References -7.1. Normative References +6.1. Normative References [FIPS180-4] Department of Commerce, National., "NIST FIPS 180-4, Secure Hash Standard", March 2012, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC5116] McGrew, D., "An Interface and Algorithms for Authenticated Encryption", RFC 5116, DOI 10.17487/RFC5116, January 2008, . - [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an - IANA Considerations Section in RFCs", BCP 26, RFC 5226, - DOI 10.17487/RFC5226, May 2008, - . - [RFC5869] Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)", RFC 5869, DOI 10.17487/RFC5869, May 2010, . [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, June 2014, . [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, June 2014, . [RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May 2015, . -7.2. Informative References +6.2. Informative References [AEBounds] Luykx, A. and K. Paterson, "Limits on Authenticated Encryption Use in TLS", March 2016, . [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. Thayer, "OpenPGP Message Format", RFC 4880, DOI 10.17487/RFC4880, November 2007, . @@ -698,25 +606,25 @@ o The JWE Initialization Vector ("iv") for each record is set to the exclusive or of the 96-bit record sequence number, starting at zero, and a value derived from the input keying material (see Section 2.3). This value is also not transmitted. o The final value is the concatenated header, JWE Ciphertext, and JWE Authentication Tag, all expressed without base64url encoding. The "." separator is omitted, since the length of these fields is known. - Thus, the example in Section 4.1 can be rendered using the JWE + Thus, the example in Section 3.1 can be rendered using the JWE Compact Serialization as: eyAiYWxnIjogImRpciIsICJlbmMiOiAiQTEyOEdDTSIgfQ..31iQYc1v4a36EgyJ. - AM6TPZfCx3aQ2jvQvlL0-JLb.21Mj951Kwe_WjluVZnmYFgs + NSmxkSVa0-MiNNuF77YHSs8.osGjXvzitKn5jnOzU-Vklg Where the first line represents the fixed JWE Protected Header, an empty JWE Encrypted Key, and the algorithmically-determined JWE Initialization Vector. The second line contains the encoded body, split into JWE Ciphertext and JWE Authentication Tag. Appendix B. Acknowledgements Mark Nottingham was an original author of this document.