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Ace:TokenStore

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Several versions of the ACE token store format exist to allow the export and interchange of tokens between the ACE Audit Manager and command line tools.

  • UNDER DEVELOPMENT*

The token store serves two purposes, first it stores a list of tokens which can used to certify the integrity of an object. Second it stores linking information that links some external identifier to a token. While the token issued by an IMS contains a name used by token requesters in order to identify token responses, this may not be adequate to identify token/file pairing as files move between systems.

The proposed format is based on a modification of the arc file format.

[token-store] ::= [token-entry] | [token-store]
[token-entry] ::= [entry-header] [identifier-list] [newline] [proof]
[entry-header] ::= [digest-algorithm] [token-class] [round] [timestamp] [length] [newline]
[identifier-list] ::= [file-identifier] [newline]| [identifier-list]
[proof] ::=
  • newline - carriage return \n
  • round - from IMS token result, round number in which this token was generated
  • digest-algorithm - from IMS token result, algorithm used to calculate hash tree.
  • token-class - from IMS token result, name of token service on IMS which issued this token
  • timestamp - from IMS token result, timestamp token was issues
  • length - length of entry starting after newline containing identifiers and proof. Users should be able to seek(length) and be positioned at the next token-entry
  • file identifier - url, unix pathname, windows structure, PURL, which an external system may refer to this file as. When packaging token stores for inclusion in a zip or tar-like package, the identifier should the path to the file relative to the token store.

Sample Entry

SHA-256 SHA-256-0 953886 2009-04-28T11:18:49.570-0400 555
/fatcat.jpg
http://www.myserver.com/fatcat.jpg

Please note, the timestamp is just for metadata purposes and should be considered trusted as it is not cryptographically linked to the proof. ACE only allows time assertions against a witness value.