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[Imported from Trac: page NewCaps/WhatCouldGoWrong, version 13]
davidsarah 2009-10-11 02:07:43 +00:00
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NewCaps/WhatCouldGoWrong.md

@ -5,19 +5,19 @@ This is about What Could Go Wrong with the "Elk Point 2" immutable file caps: <h
|#|*what bad thing could happen*|*how*|*who could do it*|*what could they target*|*what crypto property prevents it*|*how expensive to brute force* [5]footnote| |#|*what bad thing could happen*|*how*|*who could do it*|*what could they target*|*what crypto property prevents it*|*how expensive to brute force* [5]footnote|
|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^| |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^*n*^| |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^*n*+*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*). This also depends on the encryption of *K1* being deterministic and correct.|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 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 on *R* is !#2|
|7|unauthorized deletion|brute force KD|anyone|any one file|secrecy of *KD*|2^*d*^| |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| |8|unauthorized deletion|figure out the destroy key KD from Dhash|anyone|any one file|the hash function's pre-image resistance on *Dhash*|2^min(*d*,*dh*)^|
|9|denial of service|prevent access to servers holding sufficient shares (by controlling some of them, or by attacking them or the network)|anyone|any file|not prevented by crypto|n/a| |9|denial of service|prevent access to servers holding sufficient shares (by controlling some of them, or by attacking them or the network)|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*^| |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 [3]footnote|restore a deleted file's shares by controlling the relevant servers|anyone|any one file|not prevented by crypto|n/a| |11|undeletion [3]footnote|restore a deleted file's shares by controlling the relevant servers|anyone|any one file|not prevented by crypto|n/a|
|12|undeletion [3]footnote|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*^| |12|undeletion [3]footnote|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*^|
|13|accidental collision|storage indices (*S1*,*T1*) and (*S2*,*T2*) collide accidentally|n/a|any two files|approximately random distribution of hash function outputs|[4]footnote| |13|accidental collision|storage indices (*S1*,*T1*) and (*S2*,*T2*) collide accidentally|n/a|any two files|approximately random distribution of hash function outputs|[4]footnote|
where *k* = bitlength(*K1*), *n* = bitlength(*R*), *t* = bitlength(*T*), *u* = bitlength(*U*), *d* = bitlength(*KD*). where *k* = bitlength(*K1*), *n* = bitlength(*R*), *t* = bitlength(*T*), *u* = bitlength(*U*), *d* = bitlength(*KD*), *dh* = bitlength(*Dhash*).
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