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Apr
29
comment Secure order preserving hash function
Right because they can't prove that in semantic security game INT-CPA then they look at left or right in which extra restrictions are made, they stipulate that even LoR game is not enough and then they describe the ideal OPE and they compare it with a real one.
Apr
29
comment Secure order preserving hash function
if breaking means not semantically secure that implies indistinguishability which if you can recover plaintext obviously doesn't hold then it's broken...(?)
Apr
29
comment Secure order preserving hash function
Then through that attack i can break any Order preserving "encryption" scheme once i have access to an oracle that is encrypting for me... OPE
Apr
29
comment Secure order preserving hash function
what if the hash function is not publicly available and it's keyed
Apr
29
comment Secure order preserving hash function
@fgrieu Is it possible to fix a keyed hash function then that is order-preserving and first-preimage resistant?
Apr
29
comment Secure order preserving hash function
@fgrieu i am wondering if this is the only way to preserve the order. Just by prepending the value before a crypto hash...
Apr
29
comment Secure order preserving hash function
But the same approach can be applied to reserve the encryption scheme, with a binary search, given many e encryptions of ciphertexts or i am wrong...?Would a keyed order preserving hash function sounds feasible?
Apr
29
comment Secure order preserving hash function
I want a representation of plaintexts such that: 1) order of plaintexts is preserved into their scrambed representation (digest if hash ciphertext if encryption), 2)I want this to be one-way with no inversion. These requirements seem to me to resemble into a hash and not an encryption scheme. Am i wrong on that?
Apr
29
comment Secure order preserving hash function
I mean for the same reason order preserving encryption is not considered as secure encryption OPHF wouldn't considered as secure hash...
Apr
29
comment Secure order preserving hash function
Why can't be a hash? I was thinking of a hash as i don't care about decryption. I do only care for preimage resistance. In CryptoDB paper they don't say how they apply order preserving encryption. This paper "An Ideal-Security Protocol for Order-Preserving Encoding" claims to achieve the best security we can gain for order preserving encryption by mutable ciphertexts.That is ciphertexts periodically are deleted in the db. Still in the paper the way OPE as a crypto primitive is constructed is not not described in technical detailsv.Is it just multiple encryptions(AES) until order is preserved?
Apr
29
asked Secure order preserving hash function
Apr
21
comment How strong is the ECDSA algorithm?
Since supersingular curves are vulnerable to some attacks(MOV) why people still use them?
Apr
21
comment Why would anyone use an elliptic curve with a cofactor > 1?
then why we do care about even characteristic curves that imply even number of points since they are not secure?
Apr
19
comment How does order-preserving encryption work?
That approach is not secure if the same key is being used for all values. Suppose $c_1=OPE(a)=a+x$ and $c_2=OPE(b)=b+x$. Then the attacker obtains k=c2-c1 = a-b. So he knows that $a$ will in a range $[a-b,OPE(a)]$ . If $X$ is not big enough then the attacker with brute force can try all values in the range.
Apr
15
comment Recovering SHA1 knowing 2/3 of the hash generated
What is the today safe $n$ that make it impossible for an attacker to brute force in a "reasonable" time?Something greater than $80$ ?
Apr
12
accepted Why unit vectors should be encrypted bit per bit in that case?
Apr
11
revised Why unit vectors should be encrypted bit per bit in that case?
deleted 1 characters in body
Apr
11
revised Why unit vectors should be encrypted bit per bit in that case?
added 90 characters in body
Apr
11
comment How to implement order preserving encryption or order preserving hashing
I looked at the code and still it gets very complex when it comes in OPE. What they do is that they choose random numbers from a distribution and then they check for the order?Or this is the naive approach?
Apr
11
asked Why unit vectors should be encrypted bit per bit in that case?