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• 句法
• 指令
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Want-Digest HTTP header is primarily used in a HTTP request, to ask the responder to provide a digest of the requested resource using the Digest response header.

The header contains identifiers for one or more digest algorithms that the sender wishes the responder to use to create the digest. The sender may use quality values to indicate its preference ordering among the choices it offers.

若 Want-Digest does not include any digest algorithms that the server supports, the server may respond with:

• a digest calculated using a different digest algorithm, or
• a 400 Bad Request error, and include another Want-Digest header with that response, listing the algorithms that it does support.

See the page for the Digest header for more information.

Header type	General header
Forbidden header name	no

句法

Want-Digest: <digest-algorithm>
// Multiple algorithms, weighted with the quality value syntax:
Want-Digest: <digest-algorithm><q-value>,<digest-algorithm><q-value>
					

指令

<digest-algorithm>

Supported digest algorithms are defined in RFC 3230 and RFC 5843 , and include SHA-256 and SHA-512 . Some of the supported algorithms, including unixsum and MD5 are subject to collisions and are thus not suitable for applications in which collision-resistance is important.

<q-value>

quality value to apply to that option.

范例

Want-Digest: sha-256
Want-Digest: SHA-512;q=0.3, sha-256;q=1, md5;q=0
					

Basic operation

The sender provides a list of digests which it is prepared to accept, and the server uses one of them:

Request:
  GET /item
  Want-Digest: sha-256;q=0.3, sha;q=1
Response:
  HTTP/1.1 200 Ok
  Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
					

Unsupported digests

The server does not support any of the requested digest algorithms, so uses a different algorithm:

Request:
  GET /item
  Want-Digest: sha;q=1
Response:
  HTTP/1.1 200 Ok
  Digest: sha-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=
					

The server does not support any of the requested digest algorithms, so responds with a 400 error and includes another Want-Digest header, listing the algorithms that it does support:

Request:
  GET /item
  Want-Digest: sha;q=1
Response:
  HTTP/1.1 400 Bad Request
  Want-Digest: sha-256, sha-512
					

规范

规范	Title
draft-ietf-httpbis-digest-headers-latest	Resource Digests for HTTP

This header was originally defined in RFC 3230 , but the definition of "selected representation" in RFC 7231 made the original definition inconsistent with current HTTP specifications. When released, The "Resource Digests for HTTP" draft therefore will obsolete RFC 3230 and will update the standard to be consistent.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

更新 GitHub 上的兼容性数据

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
Want-Digest	Chrome 完整支持 Yes	Edge 完整支持 12	Firefox 完整支持 Yes	IE 完整支持 Yes	Opera 完整支持 Yes	Safari 完整支持 Yes	WebView Android 完整支持 Yes	Chrome Android 完整支持 Yes	Firefox Android 完整支持 Yes	Opera Android 完整支持 Yes	Safari iOS 完整支持 Yes	Samsung Internet Android 完整支持 Yes

图例

完整支持

完整支持

另请参阅

• Digest

元数据

• 最后修改： Aug 2, 2019

相关话题

1. HTTP
2. Guides:
3. Resources and URIs

   1. Identifying resources on the Web
   2. Data URIs
   3. Introduction to MIME Types
   4. Complete list of MIME Types
   5. Choosing between www and non-www URLs
4. HTTP guide

   1. Basics of HTTP
   2. HTTP 概述
   3. Evolution of HTTP
   4. HTTP Messages
   5. A typical HTTP session
   6. Connection management in HTTP/1.x
   7. Protocol upgrade mechanism
5. HTTP 安全性

   1. Content Security Policy (CSP)
   2. HTTP Public Key Pinning (HPKP)
   3. HTTP Strict Transport Security (HSTS)
   4. Cookie security
   5. X-Content-Type-Options
   6. X-Frame-Options
   7. X-XSS-Protection
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   9. Mozilla Observatory
6. HTTP access control (CORS)
7. HTTP authentication
8. HTTP caching
9. HTTP compression
10. HTTP conditional requests
11. HTTP content negotiation
12. HTTP cookies
13. HTTP range requests
14. HTTP redirects
15. HTTP specifications
16. Feature policy
17. 参考：
18. HTTP 头

    1. Accept
    2. Accept-CH
    3. Accept-CH-Lifetime
    4. Accept-Charset
    5. Accept-Encoding
    6. Accept-Language
    7. Accept-Patch
    8. Accept-Ranges
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    12. Access-Control-Allow-Origin
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    53. If-Modified-Since
    54. If-None-Match
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20. HTTP 响应状态码

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    2. 101 Switching Protocols
    3. 103 Early Hints
    4. 200 OK
    5. 201 Created
    6. 202 Accepted
    7. 203 Non-Authoritative Information
    8. 204 No Content
    9. 205 Reset Content
    10. 206 Partial Content
    11. 300 Multiple Choices
    12. 301 Moved Permanently
    13. 302 Found
    14. 303 See Other
    15. 304 Not Modified
    16. 307 Temporary Redirect
    17. 308 Permanent Redirect
    18. 400 Bad Request
    19. 401 Unauthorized
    20. 402 Payment Required
    21. 403 Forbidden
    22. 404 Not Found
    23. 405 Method Not Allowed
    24. 406 Not Acceptable
    25. 407 Proxy Authentication Required
    26. 408 Request Timeout
    27. 409 Conflict
    28. 410 Gone
    29. 411 Length Required
    30. 412 Precondition Failed
    31. 413 Payload Too Large
    32. 414 URI Too Long
    33. 415 Unsupported Media Type
    34. 416 Range Not Satisfiable
    35. 417 Expectation Failed
    36. 418 I'm a teapot
    37. 422 Unprocessable Entity
    38. 425 Too Early
    39. 426 Upgrade Required
    40. 428 Precondition Required
    41. 429 Too Many Requests
    42. 431 Request Header Fields Too Large
    43. 451 Unavailable For Legal Reasons
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    45. 501 Not Implemented
    46. 502 Bad Gateway
    47. 503 Service Unavailable
    48. 504 Gateway Timeout
    49. 505 HTTP Version Not Supported
    50. 506 Variant Also Negotiates
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    52. 508 Loop Detected
    53. 510 Not Extended
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    2. CSP: block-all-mixed-content
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