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r -> n (r would have been more consistent, but n is what the diagram uses) 

[Imported from Trac: page NewCaps/WhatCouldGoWrong, version 5]
davidsarah 2009-10-11 00:50:00 +00:00
parent 51006cf958
commit 19f88c266b
1 changed files with 5 additions and 3 deletions
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NewCaps/WhatCouldGoWrong.md

@ -3,13 +3,15 @@ This is about What Could Go Wrong with the "Elk Point 2" immutable file caps: <h
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|---|---|---|---|---|---|---| |---|---|---|---|---|---|---|
|#|*what bad thing could happen*|*how*|*who could do it*|*what could they target*|*what crypto property prevents it*|*how expensive to brute force*| |#|*what bad thing could happen*|*how*|*who could do it*|*what could they target*|*what crypto property prevents it*|*how expensive to brute force*|
|1|shape-shifter immutable file [1]footnote|collide read-cap (*R*,*T*)|creator of a file|their own file|the hash function's and cap format's collision resistance on the read-cap (*R*,*T*). This also depends on the encryption of K1 being deterministic and correct.|2^(*r*+*t*)/2^| |1|shape-shifter immutable file [1]footnote|collide read-cap (*R*,*T*)|creator of a file|their own file|the hash function's and cap format's collision resistance on the read-cap (*R*,*T*). This also depends on the encryption of *K1* being deterministic and correct.|2^(*n*+*t*)/2^|
|2|unauthorized read|attack the encryption of *K1* with *R*|anyone|any one file|the cipher's security and the secrecy of the read-key *R*|2^*r*^| |2|unauthorized read|attack the encryption of *K1* with *R*|anyone|any one file|the cipher's security and the secrecy of the read-key *R*|2^*n*^|
|3|forgery of immutable file|generate a matching read-cap (*R*,*T*) for someone else's file|anyone|any one file|the hash function's and cap format's second-pre-image resistance on (*R*,*T*)|2^*r*+*t*^| |3|forgery of immutable file|generate a matching read-cap (*R*,*T*) for someone else's file|anyone|any one file|the hash function's and cap format's second-pre-image resistance on (*R*,*T*)|2^*n*+*t*^|
|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*^| |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*^| |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 attack on *R* is !#2| |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 attack on *R* is !#2|
where *k* = bitlength(*K1*), *n* = bitlength(*R*), *t* = bitlength(*T*).
1. *shape-shifter immutable file*: creator creates more than one file matching the immutable file readcap 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 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