Linked Questions

1
vote
0answers
509 views

Is it still safe to use sha1 as an hmac hash function in 2018 [duplicate]

I'm curious if it's safe to use sha1 for an HMAC in 2018 in a platform product. A popular vendor (Twilio) uses an HMAC with sha1 with a shared secret to validate that messages they send are indeed ...
0
votes
0answers
18 views

Which SHA-1 attacks apply to TOTP tokens? [duplicate]

Update: it's actually hmac(secret, time). I'll leave the post as-is, in case someone is ever looking for the hash(secret+time) ...
27
votes
2answers
16k views

Is HMAC-MD5 considered secure for authenticating encrypted data?

I've read something to the effect that the HMAC construct is able to lessen the problem of collisions in the underlying hash. Does that mean that something like HMAC-MD5 still might be considered ...
7
votes
2answers
1k views

Could an HMAC be used as a hash?

MD5 is considered broken and SHA-1 is closely following, but HMACs built around either are still considered relatively secure. It makes me wonder if MD5 and SHA-1 HMACs can be used as secure hashes. ...
6
votes
1answer
3k views

Is PBKDF2/RFC 2898 broken because SHA1 is broken?

I was attempting to re-implement the ASP.NET Identity password hash algorithm in PHP. It uses RFC 2898, which uses HMAC SHA1. SHA1 has been broken by google. Does this mean that RFC 2898 in general ...
6
votes
2answers
215 views

What kind of attack could one perform if you generate private keys using SHA3(master_key || nonce)?

I'm aware HMAC is more appropriate than SHA3(master_key || nonce), but I do not understand what kind of attack could be performed against that strategy. How could ...
6
votes
2answers
249 views

Is the warning given by chrome warranted?

I went to a payment page on a site recently, and chrome was warning me that the page is possibly not secure, I have a very basic understanding of crypto but not enough to fully understand why this ...
1
vote
2answers
315 views

using hash function of (key||plaintext) instead of random value for IV

for a protocol which implements AES under CBC mode, an $IV $(initialization vector) is required for each encryption. Instead of picking the $IV$ randomly, is it advisable for us to set the $IV$ to be $...
3
votes
1answer
393 views

Is it a vulnerability (for message authentication) to have a variable iteration-count for PBKDF2?

The scenario: A user clicks on an encrypted file, and enters his password, in order to decrypt and authenticate it using HMAC (when its key is derived using PBKDF2). If the iteration-count is fixed, ...
0
votes
1answer
317 views

What order should these HTTPS ciphers go in to maximize security?

I want to set up a very secure-from-MITM-attacks server. I have these algorithms enabled in my nginx and I'm getting an A+ on ssllabs.com but it's complaining that my cipher strength isn't 100% and ...