Mar
11
awarded  Popular Question
Feb
25
awarded  Popular Question
Jun
7
comment Why should I use an Initialization Vector (IV) when I have unique keys?
Related: Does AES-CTR require an IV for any purpose other than distinguishing identical inputs?
May
12
awarded  Yearling
Apr
22
comment How is CipherCloud doing homomorphic encryption?
Official response: Responding to the Myths about CipherCloud’s Encryption Technology (and Hacker News discussion)
Sep
7
awarded  Critic
Mar
17
comment What is the purpose of using different hash functions for the leaves and internals of a hash tree?
Oops! Thank you for the clarification. New interpretation: The trees are secure in the context of BitTorrent because it already knows the total length of the input, so it's impossible for an attacker to add or remove leaves as would be necessary.
Mar
17
accepted What is the purpose of using different hash functions for the leaves and internals of a hash tree?
Mar
17
comment What is the purpose of using different hash functions for the leaves and internals of a hash tree?
I realized that the reason BitTorrent's Simple Merkel Trees aren't vulnerable to this is that they're padded full by adding 0-leaves (until the number of them reaches a power of two). On the other hand THEX allows unpaired leaf hashes to "float up" the tree into a spot where an internal hash would otherwise be expected.
Mar
17
comment How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
I have inquired further about this point here: What is the purpose of using different hash functions for the leaves and internals of a hash tree?
Mar
17
asked What is the purpose of using different hash functions for the leaves and internals of a hash tree?
Mar
16
revised How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
added section 2.1 from document: I haven't seen the behaviour of using different hashes for leafs and internals in other hash tree descriptions.
Mar
16
suggested suggested edit on How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
Mar
16
accepted How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
Mar
15
comment How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
@HenrickHellström Edited a bit to clarify my meaning; I'm asking about the implementation called "Tiger Tree Hash"/TTH in peer-to-peer protocols, not about Tiger-based hash trees in general.
Mar
15
revised How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
added 175 characters in body; edited title
Mar
15
revised How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
added 4 characters in body
Mar
15
asked How does a “Tiger Tree Hash” handle data whose size isn't a power of two?
Feb
13
asked Why not use CTR with a randomized IV?
Jan
4
comment Does AES-CTR require an IV for any purpose other than distinguishing identical inputs?
My tentative understanding is this: NIST SP800-38A Appendix B warns that "The initial counter blocks for each message that is encrypted under the given key must be chosen in a manner than ensures the uniqueness of all the counter blocks across all the messages". It also defines that the standard way of incrementing the counter value as what seems to be ordinary unsigned binary addition, so an IV of 0 in one message would result in its first block being ciphered in the same way as the second block of a message with an IV of 1.