Linked Questions

3 votes
2 answers
489 views

Are the following ciphersuites vulnerable? if so, what are the vulnerabilities?

Following ciphersuites found to be weak in Qualys(https://www.ssllabs.com/ssltest/analyze.html) tool: TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (0xc027) ECDH x25519 (eq. 3072 bits RSA) ...
user105523's user avatar
3 votes
2 answers
401 views

Is disabling padding integrity check in CBC implementations a good way of overcoming / mitigating padding oracle attack?

Given that CBC mode has a padding oracle attack, would disabling the padding integrity check be a good way of overcoming the vulnerability (this may result in frustration among existing users with ...
Ravindra HV's user avatar
3 votes
2 answers
280 views

Robust authentication and integrity for short OTP message

Using any of the wonders of modern cryptographic technology, how is it possible to package a tweet-sized plaintext, which is to be encrypted with a proper one-time pad, to ensure its integrity and ...
Patriot's user avatar
  • 3,132
3 votes
1 answer
2k views

New to cryptology, studying Message Authentication Codes

I understand the basic operational theory behind MAC, but I'm getting tripped up on some of the finer details. Also the differences between MAC, HMAC and MIC are getting lost on me, including the ...
Brandon's user avatar
  • 31
3 votes
2 answers
2k views

Private RSA key for HMAC key

I am creating software tokens for future request authentication, and I want to use an HMAC for the token to make them tamper-resistant. To ensure I can check the HMAC later I need a secret, persistent ...
Kyeotic's user avatar
  • 133
3 votes
1 answer
6k views

AES-CBC then SHA vs AES-GCM for encrypting and authenticating a web token

I am trying to have something like JWT but kinda ad hoc and encrypted. The token itself is simply a stringified JSON that contains the user ID and Unix timestamp. Now, I tried to use AES-128-GCM, ...
pls no's user avatar
  • 919
3 votes
1 answer
2k views

Is encrypt-and-MAC secure for AES-CTR + UMAC?

OpenSSH will (especially in older versions) use AES-CTR plus a MAC in encrypt-and-MAC. This is not secure in general (meaning that there exist secure ciphers and secure MACs such that using them in ...
Demi's user avatar
  • 4,793
3 votes
1 answer
116 views

Is it possible to add error propagation to OTP?

What would be the recipe to add error propagation to a one time pad? I.e. if I change a single letter in the clear text message, I want the encrypted message to change starting from that letter and up ...
daruma's user avatar
  • 385
2 votes
3 answers
2k views

How does one provide a secure and authentic communication channel?

Let assume two participants Alice and Bob who perform a given protocol which is a sequence of messages exchange between them. My question is: How can I provide a secure and authentic communication ...
Hamouid's user avatar
  • 149
2 votes
2 answers
410 views

Is E_k(M)||H(m) form of MAC secure?

Would this encryption and signing scenario be considered tamper-proof? ...
Evan Su's user avatar
  • 449
2 votes
1 answer
471 views

Is predictable ciphertext/plaintext bad?

I have a cryptosystem that I'm using for secure chat. It is using AES 256 (with RSA 2048 for key exchange). Would a predictable, and repetitively sent ciphertext plaintext compromise the ...
kys111's user avatar
  • 21
2 votes
1 answer
654 views

Should I be concerned about padding oracle attacks if the lifespan of my key is ~1 minute?

I'm using 4096-bit RSA to encrypt a 256-bit AES key generated client-side. The RSA ciphertext is then sent to the server, and the server decrypts the RSA ciphertext to acquire the AES key. ...
Luke Park's user avatar
  • 562
2 votes
2 answers
3k views

Encrypt-then-MAC paradigm

I read that the Encrypt-then-MAC paradigm is provably secure. From what I understand, when using for example AES for encryption and HMAC_SHA256 for MAC generation (and the keys $K_1 \neq K_2$), this ...
Martin Lundberg's user avatar
2 votes
2 answers
1k views

Avalanche noise RNG for one-time pad use

I came across this little HRNG widget and was really intrigued as I have been looking for a decent but afordable source for truly random bits to use in a one-time pad. The question is, would a HRNG ...
youjustreadthis's user avatar
2 votes
1 answer
467 views

CPA secure to CCA secure encryption

Can we use a MAC to transform a CPA secure encryption scheme into CCA secure one?
user104304's user avatar

15 30 50 per page
1 2 3
4
5
8