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Jul
5
comment What informal indicators exist for estimating the computational infeasibility of cryptographic problems?
Related question How can we reason about the cryptographic capabilities of code-breaking agencies like the NSA or GCHQ?
Jul
5
revised Where is SRP-Z from?
deleted 6 characters in body; edited tags
Jul
5
comment What are the advantages of using OFB (Output Feedback Mode)?
Could you add a reference for CTR having better security bounds?
Jul
5
reviewed Approve What are the advantages of using OFB (Output Feedback Mode)?
Jul
4
comment What are the advantages of using OFB (Output Feedback Mode)?
CBC and CFB decryption are parallelizable, so the speed advantage of CTR should only apply to encryption, not decryption.
Jul
4
comment Logjam-style attack on Factoring?
There is an technique called Batch NFS but I don't know about the details.
Jul
4
comment Parallel authentication of encrypted data. What AE type to choose?
If you have large files, why don't you split the file into chunks and encrypt these independently? That has the added advantage that you don't need to decrypt terabytes of data, only to throw them away at the end if the MAC doesn't validate.
Jul
3
comment Does XTS provide random write access?
@elisae__ The attacker learns which blocks (at the same position) changed between versions. If blocks consist of a single bit (xor based streamciphers, including CTR mode), they learn which bits are identical, which is often enough to recover the message. If you use AES-XTS they learn which 16 byte blocks are identical. If you use some kind of wide block cipher construction to get 4096 byte blocks, they only learn if such a large block changed. But since you need to rewrite a whole block at once, larger blocks limit random access operations.
Jul
3
revised Does XTS provide random write access?
added 307 characters in body
Jul
3
comment Can passwords be stored securely so that a similarity comparison can be made?
But it doesn't prevent somebody from alternating between two dissimilar passwords.
Jul
3
reviewed No Action Needed Can passwords be stored securely so that a similarity comparison can be made?
Jul
3
comment Can passwords be stored securely so that a similarity comparison can be made?
Of course this only works for the immediately prior password and not for comparing with older passwords.
Jul
3
comment Does XTS provide random write access?
How are you protecting integrity? A merkle tree of hashes/MACs?
Jul
3
answered Does XTS provide random write access?
Jul
2
comment How often does RSA-OAEP have a leading zero?
@TBridges42 Depends on the most significant byte of the public key. The probability should be approximately p(MSB(ciphertext)=0) = 1/MSB(public key).
Jul
2
reviewed Reject Is One Time Pad something like this?
Jul
1
comment How often does RSA-OAEP have a leading zero?
If this is about the most significant byte of the ciphertext being zero, it's possible. Padding affects the plaintext.
Jul
1
reviewed No Action Needed Is this client-side password hash scheme secure?
Jul
1
reviewed Reviewed Is this client-side password hash scheme secure?
Jul
1
comment Is this client-side password hash scheme secure?
For code spanning several lines, I recommend indenting it with 4 spaces, instead of using a <code> html tag.