Changes between Version 7 and Version 8 of NewCaps/WhatCouldGoWrong

Timestamp:

2009-10-11T01:34:51Z (15 years ago)

Author:

davidsarah

Comment:

fix undeletion attacks

NewCaps/WhatCouldGoWrong

@@ -12 +12 @@
 ||9||denial of service||prevent access to servers holding sufficient shares (by controlling some of them, or by attacking them)||anyone||any file||not prevented by crypto||n/a||
 ||10||cause invalid share to verify||generate (''K1enc'',''Dhash'',''V'') that hash to someone else's (''T'',''U''), and copy their ''S''||anyone||any one file||the hash function's second-pre-image resistance on (''T'',''U'')||2^''t''+''u''^||
-||11||undeletion||undelete a file (making it readable by existing read caps) by restoring its shares||anyone||any one file||assuming a "tombstone" is present on all relevant servers: same as !#10||2^''t''+''u''^||
+||11||undeletion [footnote 3]||restore the file's shares by controlling the relevant servers||anyone||any one file||not prevented by crypto||n/a||
+||12||undeletion [footnote 3]||generate matching (''R'',''T'',''U'') for a deleted file||anyone||any one file||the hash function's and cap format's second-pre-image resistance on (''R'',''T'',''U'')||2^''n''+''t''+''u''^||
 
 where ''k'' = bitlength(''K1''), ''n'' = bitlength(''R''), ''t'' = bitlength(''T''), ''u'' = bitlength(''U''), ''d'' = bitlength(''KD'').
@@ -18 +19 @@
 1. ''shape-shifter immutable file'': creator creates more than one file matching the immutable file readcap
 2. ''roadblock'': attacker prevents uploader (including repairer) from being able to write a real share into the right storage index; ''speedbump'': attacker adds his bogus share into the list of shares stored under the storage index by the same method; downloader has to download, examine, and discard the bogus (''K1enc'',''Dhash'',''V'')'s until it finds the real one
+3. ''undeletion'': attacker makes a deleted file (for which it need not have had a read cap) accessible at its previous storage index, and readable by previous read caps
 
 http://allmydata.org/pipermail/tahoe-dev/2009-October/002959.html