Questions tagged [diffie-hellman]
The Diffie–Hellman key agreement is an anonymous, non-authenticated key-agreement protocol.
278
questions
-1
votes
1
answer
621
views
DH cipher suites and DH OpenSSL Generated
I need a openssl generated diffie-hellman params for work with ECDHE or DHE cipher suites on TLSv1.2 nginx server?
0
votes
1
answer
726
views
Why is the Diffie-Hellman exchange not enough to authenticate the communication partners in IKE_SA_INIT?
The IKE_SA_INIT does create a key seed SKEYSEED from the Diffie-Hellman values and nonces. Since the exchange does sharing the secret between the communication partners, I do not understand why it is ...
1
vote
2
answers
463
views
Command to check a website is vulnerable to Logjam
I am referring this post https://www.openssl.org/blog/blog/2015/05/20/logjam-freak-upcoming-changes/ and trying to see a website is vulnerable to Logjam or not.
I try with www.google.com:443 but I am ...
- 111
0
votes
2
answers
168
views
Is there any way to send data securely from multiple As to B in the presence of eavesdropper, without losing anonymity like in a public key exchange?
Suppose I have n subordinates at work. Any subordinate should be able to submit his or her report anonymously to me via digital means.
Also suppose that I have no means of broadcasting any form of ...
2
votes
1
answer
848
views
Is there a benefit to Diffie-Hellman parameter rotation?
When setting up a web server with TLS support I've generated my dhparams with openssl dhparam -C 2048 some.pem. I understand that the output in some.pem are the parameters by which DH key exchange ...
- 145
2
votes
0
answers
209
views
ECDSA ECDH Man In The Middle Attack
We have a long-term key used for signing/verifying the ephemeral keys. The problem is we have to first share the long term public key with the other party. Is it possible to avoid a man in the middle ...
- 21
0
votes
0
answers
145
views
Is client-side password hashing still useful when using TLS? Is TLS crackable? What about PFS? [duplicate]
Is client-side password hashing still necessary / useful when using TLS? What about TLS protocols with PFS (perfect forward secrecy) like Diffie-Hellman?
Let’s say that I’m running a web application ...
- 113
2
votes
1
answer
989
views
Why do predefined FFDHE parameters containt '///////////'?
Recently, Mozilla published a new and excellent version of its SSL Configuration Generator. One of the changes compared to previous versions was to use predefined FFDHE (Finite Field Diffie-Hellman ...
- 405
1
vote
1
answer
420
views
Diffie–Hellman key exchange questions [closed]
at the moment I am working on a chat application, where more than two clients can communicate at the same time.
I just got started with the encryption so please be bear with me.
My goal is to ...
- 111
1
vote
1
answer
259
views
how are symmetric keys generated in TLS [duplicate]
My confusion stems from reading that TLS handshake uses some kind of Diffie-Hellman, when I was certain that the symmetric key was generated by a digest of earlier packets encrypted with clients ...
- 113
5
votes
1
answer
2k
views
How to decrypt Diffie-Hellman encryption in WebRTC?
I have installed a WebRTC server application, which is designed for Contact Center solutions: communicates with internal PCs in pure RTP (agents), and with external PCs (customers) using encrypted ...
- 151
1
vote
1
answer
2k
views
TLS-Handshake, Server Key Exchange, Diffie-Hellman: Where does key length come from?
Where does the key length come from?
In this example it is 2048 bits long:
Secure Sockets Layer
TLSv1.2 Record Layer: Handshake Protocol: Server Key Exchange
Content Type: Handshake (22)...
- 135
1
vote
1
answer
222
views
Self-signed certificates and ephemeral Diffie–Hellman key exchange protocol
If we use a self-signed certificate, is ephemeral Diffie–Hellman key exchange protocol vulnerable to a man in the middle attack?
- 111
6
votes
2
answers
2k
views
Diffie-Hellman with non-prime modulus
When using the Diffie-Hellman key-exchange, it is said to be important to use a safe prime. However, if a non-prime modulus with sufficient bit-length is generated, is there an attack that can be used ...
- 172
0
votes
1
answer
169
views
Public key encryption confusion
I'm learning Linux, and currently SSH. But there are details that I don't really understand.
I've seen and understood how Diffie-Hellman key exchanges work from a mathematical point of view, but what ...
0
votes
3
answers
5k
views
How to find the DH prime value (if 1024 or 2048) from Internet?
I have to ensure that the server when communicating on the Internet needs to have DH prime value of 2048 bits or greater.
I can find out the cipher suites that are used but cannot derive the DH ...
0
votes
1
answer
1k
views
OpenSSL - 2040 bit temporary key size, 2048 bit private key
Recently, I had an OpenVAS scan report that a TLS connection to Postfix used a temporary key size of 2040 bits, instead of the 2048 bits that I have set for my key size, and I have perfect forward ...
- 125
2
votes
1
answer
636
views
Perfect forward secrecy in Instant Messaging with multiple devices
I have read multiple sites online about PFS and DH but I still have a few questions.
I understand that in order to have PFS you must use different keys to encrypt messages. So your IM client could be ...
- 21
4
votes
2
answers
4k
views
How to verify Diffie Hellman uses a "Safe" prime
I'm the developer for a web application that was recently pen tested. One of the vulnerabilities reported from the pen test is that our server uses an unsafe Diffie-Hellman prime in our key exchange. ...
9
votes
1
answer
10k
views
How does TLS work (RSA, Diffie-Hellman, PFS)?
I know "How TLS works" has been discussed numerous times here and crypto, but I am still somewhat confused and would like to summarize what I know so far 1 in this giant blob of text with ...
- 219
0
votes
1
answer
168
views
Usage of SSL_CTX_use_certificate
While building a context through openssl, if I do not provide a certificate by using the function SSL_CTX_use_certificate, would all the connections from that context default to anonymous diffie-...
- 113
0
votes
1
answer
249
views
Can a DH param .pem file force the usage of only a single type of diffie-hellman exchange
Is it possible to create a diffie-hellman param .pem file to force the openssl ctx to use only a certain type of dh exchange. For example, I know that it can be used to set the length of the dh key, ...
- 113
1
vote
0
answers
895
views
Understand DHE security in TLS
SSL Labs says that a website I control supports weak ciphersuites because they have DH 1024 bit, e.g. this one: TLS_DHE_RSA_WITH_AES_256_GCM_SHA384 (0x9f).
I tried to connect to the website from my ...
- 121
4
votes
1
answer
2k
views
ECDH and static key encryption
It's been a while and I'm still trying to figure out if my understanding of ECC crypto is correct.
Basically from what I understood a purely asymmetric encryption is never used. Usually the ...
- 143
1
vote
2
answers
685
views
How to optimize the diffie hellman key exchange algorithm
I am making a chat feature in my app where I want to encrypt it E2EE, but the problem is when I start to calculate the public key (public key = g^private % n) it takes a decade to get it done. I need ...
- 13
3
votes
1
answer
792
views
BouncyCastle and Microsoft Cng ECDH secret key mismatch
I'm trying to refactor some client-side code from BouncyCastle to Microsoft Cng. I've figured out how to convert key format(ECC key blobs) between them, but I couldn't calculate the same secret.
...
- 151
2
votes
0
answers
102
views
Why Diffie-Hellman instead of just share the secret [duplicate]
I read that D-H is used to make a shared secret between parties that then they use to encrypt the messages.
This is used in TLS, for example, after the server has authenticated itself with a ...
- 163
2
votes
1
answer
843
views
Signal Protocol: How is identity exchanged if a key exchange hasn't happened yet?
On Signal's blog they mention that keys for accessing your profile are exchanged normally with your contacts using the Signal Protocol just like messages are (implying they are already contacts and ...
- 125
2
votes
0
answers
142
views
WPA technical doubts (3)
This is the third post about the set of doubts that came up when I tried to understand WPA3. I am new to this world of cyber-security so every bit of help is welcome!
Someone told me that in WPA2 ...
- 109
1
vote
1
answer
225
views
Different Diffie–Hellman key per site?
I recently put each of my sites through the ssl labs analyzer and now have them all running with an A+ getting perfect scores with every metric except Key Exchange at 90.
As part of this I have ...
- 163
1
vote
0
answers
254
views
Advantage Of ECDH-RSA over RSA Ciphersuites In TLS
If ECDH-RSA is used for key exchange, this is what happens:
The server has its public ECDH parameter embedded within its certificate. The client generates its public ECDH parameter, extracts the ...
3
votes
2
answers
1k
views
Diffie-Hellman protocol CA, confusing
In the Diffie-Hellman protocol, if the participants have their own private key and a generated public key. How can we determine whether or not they have a trusted CA for authentication or just the ...
- 31
0
votes
1
answer
329
views
understanding MITM attack [duplicate]
hi Everyone please correct me if im wrong for my understanding for the man in the middle attack used in a variant of diffie hellman key exchange .
am i right to say that a protocol is susceptible to ...
- 1
0
votes
1
answer
291
views
Why use a separate key exchange method like DH during the TLS handshake [duplicate]
Ok first off I'm very familiar with the TLS handshake, the purpose of PKI and key exchange methods.
My question is why use a complicated key exchange method like Diffie Hellman when the client could ...
- 101
3
votes
2
answers
2k
views
Is server public key and Diffie Hellman public are the same?
I am trying to understand the working of TLS. I understand that there are various way to generate the master secret used to encrypting the data. Such as DH (Ephemeral DHE) and RSA. I understand that, ...
- 1,452
2
votes
1
answer
4k
views
diffie-hellman size 2048 and key with size 1024
I want to increase the security of my Tomcat and to configure diffie-hellman module size 2048.
I want to add to my CATALINA_OPTS -Djdk.tls.ephemeralDHKeySize=2048
What happens if I have configured it ...
- 1,479
1
vote
0
answers
195
views
Diffie-Hellman in Android File Transfer application [closed]
I'm working on the famous android app to transfer files using WiFi-Direct technology:
https://github.com/Miserlou/Android-SDK-Samples/tree/master/WiFiDirectDemo
I want to implement a key exchange ...
5
votes
1
answer
3k
views
How can disabling Diffie-Hellman cipher for packet inspection be secure?
I have noticed that a number of network packet monitoring tools on the market today seem to have roughly the same recommended configuration parameters as described below:
Disable Diffie Hellman in ...
- 1,092
2
votes
1
answer
229
views
Exchange of public keys with DHE-RSA
The paper "Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice" by Adrian et al claims that the NSA might be able to eavesdrop on a large percentage of TLS connections, because they ...
- 23
1
vote
0
answers
653
views
How to perform a MITM attack on SSH exploiting the Diffie Hellman key exchange
I have an open-ended project for a class and I picked to make a tool/use existing tools and applications to exploit the Diffie-Hellman key exchange to be able to inject, modify and delete messages ...
- 11
3
votes
1
answer
10k
views
Is Diffie–Hellman key exchange protocol vulnerable to man in the middle attack?
Diffie–Hellman key exchange protocol vulnerable to man in the middle attack? If yes, then what type of MITM is that? I believe that is a replay attack or a relay attack, not sure though.
- 527
3
votes
1
answer
3k
views
Setup Wireshark to decrypt TLS_DHE
I have a passively sniffed traffic dump of client/server were packets are encrypted with cipher suite
Cipher Suite: TLS_DHE_RSA_WITH_AES_128_GCM_SHA256 (0x009e)
With a Logjam attack I managed to ...
- 33
0
votes
1
answer
251
views
Does LoraWan protocol's Over The Air Activation run Diffie Hellman?
I am looking at the LoraWan protocol specification and I want to capture the over the air activation of a device. So far I have seen the:
https://zakelijkforum.kpn.com/lora-forum-16/over-the-air-...
0
votes
2
answers
1k
views
OpenSSL Base64 output has wrong length
I try to generate an ECDH P-256 key pair as required for web push messages.
openssl ecparam -name prime256v1 -genkey -noout -out priv_key.pem
... generates the keys.
openssl ec -noout -text -in ...
- 103
10
votes
1
answer
2k
views
Why does TLS 1.3 deprecate custom DHE groups?
According to the second draft of the TLS 1.3 specification, custom DH groups have been deprecated. As we all know, hardcoded DH groups are vulnerable to a precomputation attack that allows retroactive ...
- 66.5k
2
votes
3
answers
1k
views
RSA relation to SSH key exchange
I do not fully understand SSH. I was hoping someone could fix my confusion.
When you generate an ssh key pair, you create four files.
authorized_keys, id_rsa, id_rsa.pub and known_hosts
My ...
- 23
0
votes
1
answer
647
views
Limitations of TLS Inspection when using Diffie-Hellman
It is my understanding that TLS Inspection can be carried out of two different ways:
1st Approach: Using a proxy server which negotiates TLS with both ends.
In this scenario, there would be 2 ...
- 209
0
votes
1
answer
98
views
Visual verification of DH parameter hashes vs derived password hashes
Let us assume the following: Alice and Bob are performing Diffie-Hellman key exchange over an unprotected channel. Eve is an active attacker (capable of dropping, modifying and constructing packets on ...
- 132
3
votes
1
answer
490
views
How can one guarantee that a Diffie-Hellman initial key exchange is not stored? [duplicate]
I might have missed parts of the technicality when it comes to the initial state of the key exchange. However, If I'm not wrong, if the initial key exchange is done over an insecure channel, how can ...
- 185
0
votes
1
answer
276
views
Diffie Hellman master secret TLS1.2
I have been trying to calculate the master secret used to encrypt some data using the client public key B, the server private key a and the client and server random values. I have calculated k=B^a, ...
- 159