https://wiki.mozilla.org/api.php?action=feedcontributions&feedformat=atom&user=Elie 2026-11-02T06:21:58Z User contributions MediaWiki 1.39.17 https://wiki.mozilla.org/index.php?title=Security/Features/Content_Hashing/Spec&diff=330245 2011-07-15T22:23:15Z

<p>Elie: </p> <hr /> <div>=Specification=<br /> <br /> The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external resources.<br /> <br /> <br /> =Use cases=<br /> <br /> == How to specify the element hash value ? ==<br /> <br /> What is the best way to specify the element hash ?<br /> Potential candidates:<br /> * adding a tag element : &lt;img src=&quot;a.jpg&quot; hash=&quot;yyyyyyyyyyy&quot;&gt;<br /> * Use a manifest file<br /> * Use a header <br /> <br /> = Technical issues =<br /> <br /> == External elements update ==<br /> <br /> How an external website can tell that the element request by the page was updated ?<br /> <br /> == Loading failure reporting ==<br /> <br /> How to report that an element failed to load because to the signature verification failed ? <br /> Maybe using the SCP report mechanism ?<br /> <br /> <br /> =Potential security issues=<br /> <br /> == Second image collision attack ==<br /> An attacker can potentially create a hash collision between a specially crafted file and a well known file if the hashing algorithm is weak.<br /> MD5 must be avoided at all cost.<br /> <br /> == Integrity ==<br /> Using the hash as an integrity mechanism is tricky because it can be delivered over HTTP. In this case a Man in the Middle attack can be performed.<br /> Communicate this limitations to user and developer is tricky. <br /> <br /> == Mime type confusion ==<br /> <br /> There is a potential issue with element cached as a specific mime-type and then used as another type. The canonical example being the gifjar attack.<br /> http://www.gnucitizen.org/blog/java-jar-attacks-and-features/<br /> <br /> <br /> = Previous work =<br /> <br /> Previous work on the subject:<br /> <br /> * http://wiki.whatwg.org/wiki/Link_Hashes<br /> * http://www.gerv.net/security/link-fingerprints/<br /> <br /> == Related RFCS ==<br /> <br /> <br /> * RFC 2803 - Digest Values for DOM (DOMHASH) http://tools.ietf.org/html/rfc2803 draft-hiroshi-dom-hash-00 http://tools.ietf.org/html/draft-hiroshi-dom-hash-00<br /> * RFC 3972 - Cryptographically Generated Addresses (CGA) http://tools.ietf.org/html/rfc3972<br /> * RFC 4982 - Support for Multiple Hash Algorithms in Cryptographically Generated Addresses (CGAs) http://tools.ietf.org/html/rfc4982<br /> * RFC 4982 - Support for Multiple Hash Algorithms in Cryptographically Generated Addresses (CGAs) http://tools.ietf.org/html/rfc4982<br /> * draft-ietf-csi-hash-threat-12 - SEND Hash Threat Analysis http://tools.ietf.org/html/draft-ietf-csi-hash-threat-12<br /> * draft-thiemann-hash-urn-01 - A URN Namespace For Identifiers Based on Cryptographic Hashes http://tools.ietf.org/html/draft-thiemann-hash-urn-01<br /> * RFC 2938 - Identifying Composite Media Features http://tools.ietf.org/html/rfc2938<br /> * draft-bryan-ftp-hash-08 - File Transfer Protocol HASH Command for Cryptographic Hashes http://tools.ietf.org/html/draft-bryan-ftp-hash-08<br /> * draft-ietf-ftpext2-hash-00 - File Transfer Protocol HASH Command for Cryptographic Hashes http://tools.ietf.org/html/draft-ietf-ftpext2-hash-00<br /> * draft-eaton-oauth-bodyhash-00 - OAuth Request Body Hash http://tools.ietf.org/html/draft-eaton-oauth-bodyhash-00<br /> * draft-arkko-mipv6-select-hash-00 - Selection of MIPv6 Security Level Using a Hashed Address http://tools.ietf.org/html/draft-arkko-mipv6-select-hash-00<br /> * draft-irtf-cfrg-rhash-01 - Strengthening Digital Signatures via Randomized Hashing http://tools.ietf.org/html/draft-irtf-cfrg-rhash-01</div>

Elie https://wiki.mozilla.org/index.php?title=Security/Features/Content_Hashing/Spec&diff=330243 2011-07-15T22:19:46Z

<p>Elie: </p> <hr /> <div>=Specification=<br /> <br /> The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external resources.<br /> <br /> <br /> =Use cases=<br /> <br /> == How to specify the element hash value ? ==<br /> <br /> What is the best way to specify the element hash ?<br /> Potential candidates:<br /> * adding a tag element : &lt;img src=&quot;a.jpg&quot; hash=&quot;yyyyyyyyyyy&quot;&gt;<br /> * Use a manifest file<br /> * Use a header <br /> <br /> = Technical issues =<br /> <br /> == External elements update ==<br /> <br /> How an external website can tell that the element request by the page was updated ?<br /> <br /> == Loading failure reporting ==<br /> <br /> How to report that an element failed to load because to the signature verification failed ? <br /> Maybe using the SCP report mechanism ?<br /> <br /> <br /> =Potential security issues=<br /> <br /> == Second image collision attack ==<br /> An attacker can potentially create a hash collision between a specially crafted file and a well known file if the hashing algorithm is weak.<br /> MD5 must be avoided at all cost.<br /> <br /> == Integrity ==<br /> Using the hash as an integrity mechanism is tricky because it can be delivered over HTTP. In this case a Man in the Middle attack can be performed.<br /> Communicate this limitations to user and developer is tricky. <br /> <br /> == Mime type confusion ==<br /> <br /> There is a potential issue with element cached as a specific mime-type and then used as another type. The canonical example being the gifjar attack.<br /> http://www.gnucitizen.org/blog/java-jar-attacks-and-features/<br /> <br /> <br /> = Previous work ==<br /> <br /> Previous work on the subject:<br /> <br /> * http://wiki.whatwg.org/wiki/Link_Hashes<br /> * http://www.gerv.net/security/link-fingerprints/</div>

Elie https://wiki.mozilla.org/index.php?title=Security/Features/Content_Hashing/Spec&diff=330242 2011-07-15T22:12:08Z

<p>Elie: </p> <hr /> <div>=Specification=<br /> <br /> The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external resources.<br /> <br /> <br /> =Use cases=<br /> <br /> <br /> = Technical issues =<br /> <br /> == External elements update ==<br /> <br /> <br /> =Potential security issues=<br /> <br /> == Second image collision attack ==<br /> An attacker can potentially create a hash collision between a specially crafted file and a well known file if the hashing algorithm is weak.<br /> MD5 must be avoided at all cost.<br /> <br /> == Integrity ==<br /> Using the hash as an integrity mechanism is tricky because it can be delivered over HTTP. In this case a Man in the Middle attack can be performed.<br /> Communicate this limitations to user and developer is tricky. <br /> <br /> <br /> = Previous work ==<br /> <br /> Previous work on the subject:<br /> <br /> * http://wiki.whatwg.org/wiki/Link_Hashes<br /> * http://www.gerv.net/security/link-fingerprints/</div>

Elie https://wiki.mozilla.org/index.php?title=Security/Features/Content_Hashing/Spec&diff=330240 2011-07-15T22:03:03Z

<p>Elie: </p> <hr /> <div>=Specification=<br /> <br /> The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external resources.<br /> <br /> <br /> =Use cases=</div>

Elie https://wiki.mozilla.org/index.php?title=Security/Features/Content_Hashing/Spec&diff=330239 2011-07-15T22:02:31Z

<p>Elie: Created page with &quot;=Specification= The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external reso...&quot;</p> <hr /> <div>=Specification=<br /> <br /> The content hashing mechanism aims at improving the browser caching performance and providing a means for website to enforce the integrity of their external resources.<br /> <br /> <br /> == Use cases==</div>

Elie