Network Working Group W. Hardaker
Request for Comments: 4509 Sparta
Category: Standards Track May 2006
Network Working Group W. Hardaker
Request for Comments: 4509 Sparta
Category: Standards Track May 2006
Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records (RRs)
在DNSSEC授权签署人（DS）资源记录（RRs）中使用SHA-256
Status of This Memo
关于下段备忘
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
本文件规定了互联网社区的互联网标准跟踪协议，并要求进行讨论和提出改进建议。有关本协议的标准化状态和状态，请参考当前版本的“互联网官方协议标准”（STD 1）。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
This document specifies how to use the SHA-256 digest type in DNS Delegation Signer (DS) Resource Records (RRs). DS records, when stored in a parent zone, point to DNSKEYs in a child zone.
本文档指定如何在DNS委派签名者（DS）资源记录（RRs）中使用SHA-256摘要类型。DS记录存储在父分区中时，指向子分区中的DNSKEY。
Table of Contents
目录
1. Introduction ....................................................2
2. Implementing the SHA-256 Algorithm for DS Record Support ........2
2.1. DS Record Field Values .....................................2
2.2. DS Record with SHA-256 Wire Format .........................3
2.3. Example DS Record Using SHA-256 ............................3
3. Implementation Requirements .....................................3
4. Deployment Considerations .......................................4
5. IANA Considerations .............................................4
6. Security Considerations .........................................4
6.1. Potential Digest Type Downgrade Attacks ....................4
6.2. SHA-1 vs SHA-256 Considerations for DS Records .............5
7. Acknowledgements ................................................5
8. References ......................................................6
8.1. Normative References .......................................6
8.2. Informative References .....................................6
1. Introduction ....................................................2
2. Implementing the SHA-256 Algorithm for DS Record Support ........2
2.1. DS Record Field Values .....................................2
2.2. DS Record with SHA-256 Wire Format .........................3
2.3. Example DS Record Using SHA-256 ............................3
3. Implementation Requirements .....................................3
4. Deployment Considerations .......................................4
5. IANA Considerations .............................................4
6. Security Considerations .........................................4
6.1. Potential Digest Type Downgrade Attacks ....................4
6.2. SHA-1 vs SHA-256 Considerations for DS Records .............5
7. Acknowledgements ................................................5
8. References ......................................................6
8.1. Normative References .......................................6
8.2. Informative References .....................................6
The DNSSEC [RFC4033] [RFC4034] [RFC4035] DS RR is published in parent zones to distribute a cryptographic digest of one key in a child's DNSKEY RRset. The DS RRset is signed by at least one of the parent zone's private zone data signing keys for each algorithm in use by the parent. Each signature is published in an RRSIG resource record, owned by the same domain as the DS RRset, with a type covered of DS.
DNSSEC[RFC4033][RFC4034][RFC4035]DS RR在父区域中发布，以分发子级DNSKEY RRset中一个密钥的加密摘要。对于父区域正在使用的每个算法，DS RRset由父区域的私有区域数据签名密钥中的至少一个签名。每个签名都发布在一个RRSIG资源记录中，该记录与DS RRset属于同一个域，其类型为DS。
In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in [RFC2119].
本文件中的关键词“必须”、“不得”、“要求”、“应”、“不应”、“应”、“不应”、“建议”、“可”和“可选”应按照[RFC2119]中的说明进行解释。
This document specifies that the digest type code 2 has been assigned to SHA-256 [SHA256] [SHA256CODE] for use within DS records. The results of the digest algorithm MUST NOT be truncated, and the entire 32 byte digest result is to be published in the DS record.
本文档规定摘要类型代码2已分配给SHA-256[SHA256][SHA256CODE]，以便在DS记录中使用。摘要算法的结果不能被截断，整个32字节的摘要结果将发布在DS记录中。
Using the SHA-256 digest algorithm within a DS record will make use of the following DS-record fields:
在DS记录中使用SHA-256摘要算法将使用以下DS记录字段：
Digest type: 2
摘要类型：2
Digest: A SHA-256 bit digest value calculated by using the following formula ("|" denotes concatenation). The resulting value is not truncated, and the entire 32 byte result is to be used in the resulting DS record and related calculations.
摘要：使用以下公式计算的SHA-256位摘要值（“|”表示串联）。生成的值不会被截断，整个32字节的结果将用于生成的DS记录和相关计算。
digest = SHA_256(DNSKEY owner name | DNSKEY RDATA)
摘要=SHA|U 256（DNSKEY所有者名称| DNSKEY RDATA）
where DNSKEY RDATA is defined by [RFC4034] as:
其中，[RFC4034]将DNSKEY RDATA定义为：
DNSKEY RDATA = Flags | Protocol | Algorithm | Public Key
DNSKEY RDATA=标志|协议|算法|公钥
The Key Tag field and Algorithm fields remain unchanged by this document and are specified in the [RFC4034] specification.
密钥标记字段和算法字段在本文档中保持不变，并在[RFC4034]规范中指定。
The resulting on-the-wire format for the resulting DS record will be as follows:
结果DS记录的在线格式如下所示：
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Tag | Algorithm | DigestType=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ /
/ Digest (length for SHA-256 is 32 bytes) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Tag | Algorithm | DigestType=2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ /
/ Digest (length for SHA-256 is 32 bytes) /
/ /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
The following is an example DNSKEY and matching DS record. This DNSKEY record comes from the example DNSKEY/DS records found in section 5.4 of [RFC4034].
以下是DNSKEY和匹配DS记录的示例。此DNSKEY记录来自[RFC4034]第5.4节中的DNSKEY/DS记录示例。
The DNSKEY record:
DNSKEY记录：
dskey.example.com. 86400 IN DNSKEY 256 3 5 ( AQOeiiR0GOMYkDshWoSKz9Xz fwJr1AYtsmx3TGkJaNXVbfi/ 2pHm822aJ5iI9BMzNXxeYCmZ DRD99WYwYqUSdjMmmAphXdvx egXd/M5+X7OrzKBaMbCVdFLU Uh6DhweJBjEVv5f2wwjM9Xzc nOf+EPbtG9DMBmADjFDc2w/r ljwvFw== ) ; key id = 60485
dskey.example.com。86400 IN DNSKEY 256 3 5（AQOeiiR0GOMYkDshWoSKz9Xz fwJr1AYtsmx3TGkJaNXVbfi/2pHm822aJ5iI9BMzNXxeYCmZ drd99wywywyqusdjmmmaphxdvx egXd/M5+X7OrzKBaMbCVdFLU uh6dhwjbjevv5f2wjm9xzc nOf+EPbtG9DMBmADjFDc2w/r ljwvFw=）；钥匙id=60485
The resulting DS record covering the above DNSKEY record using a SHA-256 digest:
结果DS记录使用SHA-256摘要覆盖上述DNSKEY记录：
dskey.example.com. 86400 IN DS 60485 5 2 ( D4B7D520E7BB5F0F67674A0C CEB1E3E0614B93C4F9E99B83 83F6A1E4469DA50A )
dskey.example.com。DS 60485 5 2中的86400（D4B7D520E7BB5F0F67674A0C CEB1E3E0614B93C4F9E99B83 83F6A1E4469DA50A）
Implementations MUST support the use of the SHA-256 algorithm in DS RRs. Validator implementations SHOULD ignore DS RRs containing SHA-1 digests if DS RRs with SHA-256 digests are present in the DS RRset.
实现必须支持在DS RRs中使用SHA-256算法。如果RRDS-DS在RRSHA-1中包含摘要，则应忽略其中的256个摘要。
If a validator does not support the SHA-256 digest type and no other DS RR exists in a zone's DS RRset with a supported digest type, then the validator has no supported authentication path leading from the parent to the child. The resolver should treat this case as it would the case of an authenticated NSEC RRset proving that no DS RRset exists, as described in [RFC4035], Section 5.2.
如果验证器不支持SHA-256摘要类型，并且区域的DS RRset中不存在具有受支持摘要类型的其他DS RR，则验证器没有受支持的从父级到子级的身份验证路径。如[RFC4035]第5.2节所述，冲突解决程序应将此情况视为经验证的NSEC RRset证明不存在DS RRset的情况。
Because zone administrators cannot control the deployment speed of support for SHA-256 in validators that may be referencing any of their zones, zone operators should consider deploying both SHA-1 and SHA-256 based DS records. This should be done for every DNSKEY for which DS records are being generated. Whether to make use of both digest types and for how long is a policy decision that extends beyond the scope of this document.
因为区域管理员不能控制支持SHA256的部署速度，因为它们可能引用它们的任何区域，区域操作员应考虑部署SHA-1和SHA256为基础的DS记录。应针对生成DS记录的每个DNSKEY执行此操作。是否同时使用这两种摘要类型以及使用多长时间是超出本文档范围的政策决策。
Only one IANA action is required by this document:
本文件仅要求一项IANA行动：
The Digest Type to be used for supporting SHA-256 within DS records has been assigned by IANA.
IANA已指定用于支持DS记录中的SHA-256的摘要类型。
At the time of this writing, the current digest types assigned for use in DS records are as follows:
在撰写本文时，分配用于DS记录的当前摘要类型如下：
VALUE Digest Type Status 0 Reserved - 1 SHA-1 MANDATORY 2 SHA-256 MANDATORY 3-255 Unassigned -
值摘要类型状态0保留-1 SHA-1必需2 SHA-256必需3-255未分配-
A downgrade attack from a stronger digest type to a weaker one is possible if all of the following are true:
如果满足以下所有条件，则可能会从更强的摘要类型降级到较弱的摘要类型：
o A zone includes multiple DS records for a given child's DNSKEY, each of which uses a different digest type.
o 区域包含给定子级DNSKEY的多个DS记录，每个记录使用不同的摘要类型。
o A validator accepts a weaker digest even if a stronger one is present but invalid.
o 验证器接受较弱的摘要，即使存在较强的摘要但无效。
For example, if the following conditions are all true:
例如，如果以下条件均为真：
o Both SHA-1 and SHA-256 based digests are published in DS records within a parent zone for a given child zone's DNSKEY.
o 基于SHA-1和SHA-256的摘要都发布在给定子区域DNSKEY的父区域内的DS记录中。
o The DS record with the SHA-1 digest matches the digest computed using the child zone's DNSKEY.
o 具有SHA-1摘要的DS记录与使用子区域的DNSKEY计算的摘要相匹配。
o The DS record with the SHA-256 digest fails to match the digest computed using the child zone's DNSKEY.
o 具有SHA-256摘要的DS记录与使用子区域的DNSKEY计算的摘要不匹配。
Then, if the validator accepts the above situation as secure, then this can be used as a downgrade attack since the stronger SHA-256 digest is ignored.
然后，如果验证器认为上述情况是安全的，那么这可以被用作降级攻击，因为更强的SHA-256摘要被忽略。
Users of DNSSEC are encouraged to deploy SHA-256 as soon as software implementations allow for it. SHA-256 is widely believed to be more resilient to attack than SHA-1, and confidence in SHA-1's strength is being eroded by recently announced attacks. Regardless of whether the attacks on SHA-1 will affect DNSSEC, it is believed (at the time of this writing) that SHA-256 is the better choice for use in DS records.
鼓励DNSSEC用户在软件实现允许的情况下尽快部署SHA-256。人们普遍认为SHA-256比SHA-1更能抵御攻击，最近宣布的攻击削弱了人们对SHA-1实力的信心。无论对SHA-1的攻击是否会影响DNSSEC，都认为（在撰写本文时）SHA-256是DS记录中使用的更好选择。
At the time of this publication, the SHA-256 digest algorithm is considered sufficiently strong for the immediate future. It is also considered sufficient for use in DNSSEC DS RRs for the immediate future. However, future published attacks may weaken the usability of this algorithm within the DS RRs. It is beyond the scope of this document to speculate extensively on the cryptographic strength of the SHA-256 digest algorithm.
在本出版物发表时，SHA-256摘要算法被认为在不久的将来足够强大。它也被认为足以在不久的将来用于DNSSEC DS RRs。然而，未来发布的攻击可能会削弱该算法在DS RRs中的可用性。广泛推测SHA-256摘要算法的密码强度超出了本文件的范围。
Likewise, it is also beyond the scope of this document to specify whether or for how long SHA-1 based DS records should be simultaneously published alongside SHA-256 based DS records.
同样，指定基于SHA-1的DS记录是否应与基于SHA-256的DS记录同时发布或发布多长时间也超出了本文件的范围。
This document is a minor extension to the existing DNSSEC documents and those authors are gratefully appreciated for the hard work that went into the base documents.
本文件是对现有DNSSEC文件的一个小扩展，感谢这些作者为基础文件所做的辛勤工作。
The following people contributed to portions of this document in some fashion: Mark Andrews, Roy Arends, Olafur Gudmundsson, Paul Hoffman, Olaf M. Kolkman, Edward Lewis, Scott Rose, Stuart E. Schechter, Sam Weiler.
以下人员以某种方式对本文件的某些部分做出了贡献：马克·安德鲁斯、罗伊·阿伦兹、奥拉弗尔·古德蒙德森、保罗·霍夫曼、奥拉夫·M·科尔克曼、爱德华·刘易斯、斯科特·罗斯、斯图亚特·E·谢赫特、山姆·韦勒。
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2119]Bradner，S.，“RFC中用于表示需求水平的关键词”，BCP 14，RFC 2119，1997年3月。
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, March 2005.
[RFC4033]Arends，R.，Austein，R.，Larson，M.，Massey，D.，和S.Rose，“DNS安全介绍和要求”，RFC 4033，2005年3月。
[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, March 2005.
[RFC4034]Arends，R.，Austein，R.，Larson，M.，Massey，D.，和S.Rose，“DNS安全扩展的资源记录”，RFC 40342005年3月。
[RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, March 2005.
[RFC4035]Arends，R.，Austein，R.，Larson，M.，Massey，D.，和S.Rose，“DNS安全扩展的协议修改”，RFC 4035，2005年3月。
[SHA256] National Institute of Standards and Technology, "Secure Hash Algorithm. NIST FIPS 180-2", August 2002.
[SHA256]国家标准与技术研究所，“安全哈希算法，NIST FIPS 180-2”，2002年8月。
[SHA256CODE] Eastlake, D., "US Secure Hash Algorithms (SHA)", Work in Progress.
[SHA256CODE]Eastlake，D.，“美国安全哈希算法（SHA）”，正在进行中。
Author's Address
作者地址
Wes Hardaker Sparta P.O. Box 382 Davis, CA 95617 USA
美国加利福尼亚州戴维斯市韦斯哈达克斯巴达邮政信箱382号，邮编95617
EMail: hardaker@tislabs.com
EMail: hardaker@tislabs.com
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