Questions tagged [handshake]
The handshake tag has no usage guidance.
78 questions
1
vote
0
answers
42
views
Why in this TLS handshake, the ClientHello,ServerHello, etc are not Piggybacked in the ACKs packets? [closed]
In the TLS handshake, I noticed that key messages like ClientHello and ServerHello aren't piggybacked onto ACK packets and are instead sent as separate packets. From a networking perspective, this ...
- 197
1
vote
1
answer
119
views
Wifi Handshake Hijack
In a normal wifi network, after authentication we associate and then perform a handshake (WPA2: 4-way handshake, WPA3: dragonfly handshake) with the AP. How does a client now know that the frames ...
- 13
2
votes
1
answer
493
views
server negotiating TLS1.3 but sent TLS1.2 ciphersuite
I sent a client hello indicating TLS1.3 support, and it contains a list of all ciphersuites that support TLS1.3, TLS1.2 and TLS1.1
And consider server negotiated TLS1.3 indicating serverHello....
- 51
1
vote
1
answer
118
views
In TLS1.3 can the client hello have the extensions which were not sent as part of HelloRetryRequest
I am having a Handshake session of PSK_only mode in TLS1.3 , where I use PSK's established out of band.
consider, client Hello is sent with the extensions of supported_versions, PreSharedKey, ...
- 51
2
votes
1
answer
63
views
Why is the "intermediate" challenge needed in Bluetooth ECDH since the "real" verification is performed at the end with code comparison?
Why is step 4 needed? What does it protect in terms of security? Doesn't the protection arrives from the last step so when Va and Vb (so called TK, Temporary Keys) are compared?
Other thing: I read ...
- 197
1
vote
0
answers
288
views
aireplay-ng --deauth never finds BSSID available
I've been trying to crack wifi wpa2 handshake using airodump-ng and aireplay-ng.
I'm using alfa awus-036acs adapter.
sudo airodump-ng wlan0
sudo airodump-ng --bssid MAC ADDR of AP --channel 1 -w ...
4
votes
1
answer
2k
views
What purpose do nonces serve in the TLS 1.3 handshake?
In general, I understand that nonces are used to prevent replay attacks, but in the case of a TLS 1.3 handshake, the Client/Server Hello message contains their public keys. Considering that keys are ...
- 43
1
vote
0
answers
100
views
What is sequence number and why is it used as the ACK number for the next ACK packet? [closed]
I am currently trying to learn the TCP session creating (3 way handshake) process in detail. I was wondering what the sequence number means and also why is the ack num for the next ACK packet always ...
- 11
1
vote
0
answers
2k
views
SSL handshake failure | Client hello(success) -> Server ACK (success) -> server RST (connection closed)
I was running MQTT broker in my pc and tried to connect to it via mqtt client in same PC. using x509 cert for mutual tls. SSL Handshake was failing with RST from server. This was happening only in my ...
- 11
0
votes
2
answers
124
views
Web request TLS
What version of TLS would be required for a router that separates client requests from a web server behind a router?
Let's say the supported TLS client is 1.2 and so is the web server, BUT the router ...
- 3
4
votes
1
answer
1k
views
Is brute force for SSH similar to cracking WPA2 handshake?
I heard recently that WPA2 passwords can be brute forced if somebody captures handshake (which is not very difficult). Can somebody tell if a similar method exists for cracking SSH traffic? I mean ...
- 143
0
votes
1
answer
698
views
Who starts with change cipher spec in a TLS handshake?
After looking at many explanations about the TLS handshake I noticed that sometimes the server starts with the change cipher spec command and sometimes the client starts with it.
I'm wondering why. Is ...
0
votes
0
answers
28
views
Which Keys TLS uses? [duplicate]
I know that in TLS 1.2 the client generates PMS (Pre Master Secret) which is used to get master_secret and Key_Block.
Where Key_Block combined with clinet_random and server_random gives us: clientMAC, ...
- 19
0
votes
2
answers
2k
views
TLS1.3 handshake encryption
I was reading about TLS1.3 and my question is that are the server hello extensions encrypted? Why is it so and how are they encrypted?
- 3
1
vote
2
answers
3k
views
How browsers know which TLS handshake to use (1.2 vs. 1.3)
TLS 1.3 has a bit different handshake messages than 1.2 (and older) had. The client is supposed to send DH parameters directly in the first Client Hello message. How do browsers know if that's what ...
- 459
0
votes
0
answers
224
views
Mutual TLS on OpenSSL - When does the server generate the CertificateVerify message?
When I am testing mutual TLS handshake performance on TLS1.3 using OpenSSL, I find a very wired thing:
I created two groups of servers and clients:
Server1 has a certificate signed using RSA3072, and ...
- 11
1
vote
1
answer
627
views
Block inbound TCP segments with ACK=0 vs Block inbound TCP segments with SYN=1, how are they same?
Blocking inbound TCP segments with ACK=0
Blocking inbound TCP segments with SYN=1
Both prevent external clients from making TCP connections to internal clients, but allow internal clients to connect ...
- 11
1
vote
1
answer
4k
views
How is the MIC (message integrity code) generated in WPA2?
We know that in WPA2's four-way handshake, a MIC is generated in order verify the supplicant (client). But how it is generated? Is something hashed to get the MIC? The PTK (pairwise transient key) ...
- 13
0
votes
0
answers
459
views
symmetric key generation in TLS 1.3
Am trying to understand the phase where the symmetric key is getting generating. From what I am understanding Diffie-Hellman is used to derive the symmetric key in TLS1.3
I am reading this tls ...
- 71
2
votes
1
answer
3k
views
What is the relation between "signature_algorithms" handshake extension and TLS ciphersuite
I am learning TLS handshake and find client/serve will negotiate a cihpersuite during client/server hello.
Usually, the last part of a ciphersuite is a hash algorithm, like SHA256 in ECDHE-ECDSA-...
- 125
1
vote
0
answers
514
views
SSL Handshake in Android via Bluetooth Classic [closed]
I am working on implementing an Android App (client) which will be connected to Raspberry Pi (server) via Bluetooth Classic.
To make data transfer securely, I want to implement SSL encryption between ...
- 11
3
votes
1
answer
453
views
Why can SSH negotiatie two different encryption and authentication algorithms?
I recently found out, that according to the RFC, SSH can negotiate two different cipher (and MAC) algorithms for server-to-client-encryption and for client-to-server-encryption (check section 7.1. for ...
- 1,282
-1
votes
1
answer
175
views
Strong TLS parameters even though MITM is being performed
I am performing a MITM attack against my own network using bettercap and https proxy.
On my client-side I use the Google Chrome browser and navigate to https://webs.com
At the same time I use a script ...
- 1
1
vote
1
answer
462
views
TLS- Key exchange for session keys. Why?
I have a question about the Key Exchange Algorithm used in TLS process.
I have read that the Key Exchange algorithm is used by client and server to exchange session keys.
Do the client and server ...
- 11
1
vote
1
answer
157
views
Is it possible that a single handshake can have 2 TLS versions included?
I am seeing different TLS versions (1.3 and 1.2) in the handshake and intermittently it fails with this error:
TLSv1.3 (OUT), TLS handshake, Client hello (1):.
2020-05-28T14:44:00Z.664 [thread-...
2
votes
1
answer
2k
views
Not able to capture 4 way handshake using airodump-ng
I am not able capture 4 way handshake, I also tried manually disconnecting and reconnecting my device to the network in hope that airodump-ng will capture the handshake but no luck. I checked the ...
- 21
0
votes
1
answer
1k
views
How does client verify the certificate provided by the server which is signed by different intermediate CA
I am creating a c++ secure client-server application using openssl library. I am still not clear about some aspects of the SSLHandshake procedure
I have enabled Mutual TLS in-order verify the both ...
- 147
1
vote
0
answers
230
views
How does BLE secure connection ensure man in the middle protection?
I understand BLE secure connection pairing mode is improvement over Legacy Pairing. The issue with legacy pairing was intial TK value can easily be bruteforce by an attacker.
In contrast, in secure ...
0
votes
1
answer
2k
views
What is the role of leaf certificate private key In TLS handshake [duplicate]
What is the role of leaf certificate's private key if this certificate is signed by the intermediate certificate's private key and the certificate signature will only be validated using its public ...
- 459
1
vote
0
answers
128
views
How are symmetric encryption algorithms tracked once handshake is complete in common secure communication protocols?
My understanding is that most secure web communication protocols ultimately want to agree on a symmetric encryption algorithm to use for sending and receiving data. Once an algorithm is agreed upon by ...
- 11
0
votes
0
answers
38
views
Where the certificate public and private keys take a place? [duplicate]
I was reading this topic which talks about the handshake process and key exchange
https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_7.1.0/com.ibm.mq.doc/sy10660_.htm
The article says that the ...
- 459
2
votes
0
answers
125
views
Which messages are included in (D)TLS Finished message's verify_data field for session resumption
The https://www.rfc-editor.org/rfc/rfc5246#section-7.4.9 states which messages are included for PRF computation that is included in Finished messages
It is clear for 'regular' (initial) handshake
But ...
- 121
2
votes
0
answers
335
views
TLS 1.2. Handshake: Where do Client and Server negotiate how the master key is built from randoms and pre?
I am currently trying to solve an exercise where I should look at a TLS 1.2 handshake trace while having access to pre and both randoms (server random and client random).
In order to decrypt ...
- 175
3
votes
1
answer
528
views
TLS 1.2 Handshake: Does the server have to take all extensions sent by the Client?
I am unsure about how extensions are handled in TLS v1.2.
During the handshake, the client is able to add some extensions during ClientHello. As far I understood, the server can pick arbitrary ...
- 175
0
votes
1
answer
265
views
Is Certification path construction algorithm needed for SSL/TLS?
In the TLS Handshake a Certificate message is sent. This message contains the (chain of) certificates needed to validate the provided certificate of the communicating party.
However, I have also ...
- 15
0
votes
1
answer
993
views
SSL server sends wrong certificate when accessed via Java
In my project I have to integrate with another system which uses quite specific SSL (and also specific cipher suite).
Here's what I mean.
Whenever I try to access the server with Java (send a request)...
- 15
2
votes
1
answer
461
views
Does the SSL record protocol encrypt the handshake protocol too?
As I know the first communication protocol which establishes between client and server in SSL is handshaking protocol and as this site says:
The SSL record protocol is used to transfer any data ...
- 121
1
vote
1
answer
524
views
Does a TLS client needs to support one of the named groups (curves?) supported by the server for TLS handshake to succeed?
Does a TLS client needs to support one of the named groups (curves?) supported by the server for TLS handshake to succeed?
Longer version:
I'm running a web site using Windows Server 2016. The web ...
- 93
1
vote
2
answers
235
views
Handshake without asymmetric encryption
One of my teacher said "Without asymmetric encryption, we would be forced to use third-party to initiate any connection".
I don't understand how it can be possible, what if an attack occur during the ...
- 91
0
votes
0
answers
19
views
Which part/step of the TLS handshake is essential for providing PFS? [duplicate]
I would say the key exchange part, because PFS is used only during the key exchange of server and client.
Am I right or have I overlooked something?
- 1
2
votes
1
answer
366
views
TLS handshake random bytes reused
What would happen if the random bytes provided by the client and the server in the first two messages would be reused by one peer/by both peers?
I think it would highly reduce the provided security, ...
- 123
0
votes
1
answer
700
views
Why is there only two packets in a TLS handshake?
I captured my network traffic to a web server and the SSL Handshake consists only of two packets.
Why does that happen and why aren't there all the other packets?
- 1
1
vote
2
answers
7k
views
SSL handshake not visible in Wireshark
In my organization we have a cloud proxy that work on a loopback address. The vendor of this proxy has deployed an app on our machine which listens on the loopback address.
I have captured the apps ...
20
votes
3
answers
7k
views
Can attackers change the public key of certificate during the SSL handshake
The communication is not encrypted during the SSL handshake. If an attacker conducts a man in the middle attack between server and client to capture the certificate, and change the public key in the ...
- 363
2
votes
0
answers
3k
views
Airgeddon-ng Handshake fail [closed]
I've followed the following instructions below. This is a freshly installed Parrot OS, not using VirtualBox and etc. I am also using Alfa AWUS036NHA wifi adapter.
ifconfig
sudo airmon-ng start wlan1 (...
- 21
1
vote
1
answer
330
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
0
votes
1
answer
276
views
Do wifi access points and routers get some kind of data from devices when a device is able to see them?
I was wondering if when a router is broadcasting its signal, it is able to handshake with devices that are wifi enabled and looking for a wifi network to connect and get some info from them?
1
vote
1
answer
645
views
Is it possible to setup 1-way TLS client authentication without server certificates?
Is it possible with TLS to only authenticate the client? In other words can one-way TLS be setup in such a way that only the host initiating the connection uses a client certificate and the second ...
- 11
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
3
votes
1
answer
903
views
Authentication handshake between two independent apps
I need help on a solution for below scenario from a security perspective.
Scenario:
There are two independent web applications App1 and App2.
User will log in to App1 by performing authentication ...
- 31