From e541673fbadf1cac234ded9f015114436f823341 Mon Sep 17 00:00:00 2001
From: davidsarah <>
Date: Sun, 11 Oct 2009 01:18:11 +0000
Subject: [PATCH] add attack on verify cap

[Imported from Trac: page NewCaps/WhatCouldGoWrong, version 7]
---
 NewCaps/WhatCouldGoWrong.md | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/NewCaps/WhatCouldGoWrong.md b/NewCaps/WhatCouldGoWrong.md
index 16921bd..80baf21 100644
--- a/NewCaps/WhatCouldGoWrong.md
+++ b/NewCaps/WhatCouldGoWrong.md
@@ -9,11 +9,13 @@ This is about What Could Go Wrong with the "Elk Point 2" immutable file caps: <h
 |4|roadblock or speedbump [2]footnote|generate (*K1enc*,*Dhash*,*V*) that hash to someone else's *T*, and copy their *S*|anyone|any one file|the hash function's and cap format's collision resistance on *T*|2^*t*^|
 |5|unauthorized read|attack the encryption of the plaintext with *K1*|anyone|any one file|the cipher's security and the secrecy of the encryption key *K1*|2^*k*^|
 |6|unauthorized read|figure out the input to the hash function that generates *S*|anyone|any one file|the hash function's pre-image resistance on *S*|brute force on *R* is !#2|
-|7|unauthorized deletion|brute force KD|anyone|any one file|secrecy of *KD*|
-|8|unauthorized deletion|figure out the destroy key KD from Dhash|anyone|any one file|the hash function's pre-image resistance on *Dhash*|
-|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|
+|7|unauthorized deletion|brute force KD|anyone|any one file|secrecy of *KD*|2^*d*^|
+|8|unauthorized deletion|figure out the destroy key KD from Dhash|anyone|any one file|the hash function's pre-image resistance on *Dhash*|brute force on *KD* is !#7|
+|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*^|
 
-where *k* = bitlength(*K1*), *n* = bitlength(*R*), *t* = bitlength(*T*), *d* = bitlength(*KD*).
+where *k* = bitlength(*K1*), *n* = bitlength(*R*), *t* = bitlength(*T*), *u* = bitlength(*U*), *d* = bitlength(*KD*).
 
 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