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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 ...
2
votes
1answer
123 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 ...
1
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1answer
92 views

how are symmetric keys generated in TLS [duplicate]

My confusion stems from reading that TLS handshake uses some kind of Diffie Hellmann, when I was certain that the symmetric key was generated by a digest of earlier packets encrypted with clients ...
2
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1answer
166 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 ...
1
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1answer
135 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)...
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0answers
78 views

Is the server's private key needed in the Diffie Hellman key exchange? [duplicate]

I understand the Diffie Hellman key exchange. What I don't understand is the role the server's private key plays in it. I'm not talking about the servers generated secret. I understand that purpose ...
0
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2answers
373 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 ...
2
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1answer
522 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. ...
2
votes
1answer
542 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 the hope ...
1
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0answers
180 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 ...
2
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0answers
80 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 ...
1
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0answers
71 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 ...
0
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1answer
139 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 ...
3
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2answers
868 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
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1answer
1k 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 ...
3
votes
1answer
2k 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
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1answer
92 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 ...
10
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1answer
670 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 ...
0
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1answer
338 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 ...
0
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1answer
126 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, ...
1
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1answer
523 views

What's the usage of the signature algorithm in TLS_DH_* cipher suites?

According to RFC5246 A.5 there are cipher suites TLS_DH_RSA_* and TLS_DH_DSS_*. How / where does the signature algorithm RSA resp. DSA from the cipher suite come into play when using (non-ephermal) ...
1
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1answer
350 views

TLS - DHE_DSS: How does client know public DSS-server key?

I wonder where the public server key g^x for DSS authentication is communicated to the client when a DHE_DSS cipher suite is used in TLS 1.2. Precisely: A DSS certificate contains crypto parameters (...
2
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1answer
816 views

Will changing the TLS Diffie-Hellman key exchange bit length from 1024 to 2048 cause client/browser compatibility issues?

Recently discovered the need to upgrade our DH key exchange length (used for TLS) from 1024 bits to 2048 bits (due to Logjam exploit and other factors). The question is: How will making that change ...
3
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2answers
5k views

Why is the reuse of the Elliptic curve Diffie–Hellman (ECDH) public server param considered bad?

When reviewing the SSL/TLS configuration using Qualys SSL Labs, I've found that the reuse of the Elliptic curve Diffie–Hellman (ECDH) public server param was flagged. Why is the reuse of the Elliptic ...
0
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1answer
104 views

Logjam definition question

As I understand it, the Logjam TLS attack is an attack that downgrades the DHE cipher suite used by the server to DHE_EXPORT. Where the client thinks it is talking DHE 512 and the server things it's ...
10
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1answer
5k views

When exactly is Diffie-Hellman used in TLS?

I'm aware that Diffie-Hellman is a key exchange algorithm whereas RSA is an asymmetric encryption algorithm. I have the following questions: During TLS handshake, will both RSA and DH be used? (I ...
1
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1answer
373 views

Are public/private keys needed when using Diffie-Hellman with TLS

When using RSA for key exchange in TLS, the role of the public key embedded in the certificate is clear: for asymmetric encryption when sending the master key, which the server can decode using its ...
0
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0answers
90 views

How is DH and RSA used together in HTTPS? [duplicate]

I'm trying to get my head around how DH and RSA are used in HTTPS. I'm sorry if this is a duplicate. I've done research into what RSA and DH are, but I'm trying to figure out how they are used ...
2
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2answers
8k views

Understanding SSL man-in-the-middle and its limitations

I’m trying to develop a good sense of how an SSL man-in-the-middle(s) (MITM) works. As I understand it, MITMs do their work in one of two ways: Decrypt the SSL by having a copy of the server’s ...
0
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1answer
808 views

SSL/TLS - Certificate chain validation result in “Invalid authentication type: DHE_RSA”

I have an application that connects to a remote web service deployed on HTTPS. Our application uses FIPS-140 Level-1 for SSL/TLS connectivity, and is based on JCE providers of RSA (the company). com....
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0answers
686 views

Usage of Diffie Hellman key exchange in TLS [duplicate]

As far as I know, this is the process of establishing a TLS connection between a client and a web server: Client sends a TLS request (using a packet called Client Hello) to the server. Server answers ...
0
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2answers
246 views

Perfect forward secrecy using XOR

I understand that Perfect Forward secrecy is meant to prevent the data sent between the client and server being decrypted in case the private key is leaked some time after the data being sent. But ...
6
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2answers
1k views

What are the performance differences (for client and server) between DHE and ECDHE in TLS?

My question is about the client and server performance for (EC)DHE. I am having difficulties in understanding this picture (which is based on numbers from Ivan Ristic' book "Bulletproof SSL and TLS"). ...
17
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2answers
2k views

Why is Mozilla recommending predefined DHE groups?

In a revision dated 2016-10-31, Mozilla changed their Server Side TLS recommendation from generating a random DH group to the ones published in RFC 7919. Mozilla claims: These groups are audited ...
0
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1answer
557 views

How to sniff ECDH HTTPS traffic?

Our company currently sniffs encrypted RSA traffic using a network tap. Would this still be possible using ECDH? I guess not. Are there commercial alternatives, like placing an agent on the ...
1
vote
1answer
3k views

What does “Server Temp Key” mean in an openssl output?

I am using openssl 1.0.1e-fips. When I ran the following against my server, I get a line in the output that begins with Server Temp Key: $ openssl s_client -cipher DHE-RSA-AES128-SHA -connect ...
0
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2answers
3k views

OpenVPN: How safe is a 24-7 open port static key setup? With proper encryption used. (AES256)

In a normal setup (cert), you have a strong encryption - just like here - for example, AES256. But you also use dh and the tls params. Just to be absolutely secure. Now, if you use the static key ...
0
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1answer
118 views

Usage of the permanent RSA private key in ECDHE-RSA-AES scheme

I was wondering if in SSL/TLS negotiation process, there is another role for the RSA permanent private key in ECDHE-RSA-AES scheme besides signing the DH public key for authenticating the identity of ...
0
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1answer
324 views

How to enable DH_RSA instead of DHE_RSA?

I generated DH parameters and set at server side. it always select cipher suite DHE_RSA? Is there any reason that DH parameter have to set server side only. Ephemeral DH: what is changed P and g ...
1
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0answers
1k views

End-To-End encrypted calls over GSM transport (not data / VoIP)

As the issue stands, it should be (or could be) possible, to encrypt voice, that's being passed through GSM voice call in such way, so that it's end-to-end encrypted. Ideally in form similar to what ...
6
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0answers
93 views

Share diffie hellman group between servers [duplicate]

I'm deploying several servers with TLS. The servers are different but related and each having their own certificate generated by letsencrypt. To increase the security, I'm generating my own Diffie ...
1
vote
1answer
420 views

How to verify the signature of DHE_RSA server parameters (TLS 1.2)?

By reading the TLS 1.2 specs I have been able to manually decrypt/encrypt pretty much all the steps of a TLS connection (DHE_RSA_AES_CBC_128_SHA cipher suite). One of things I am missing is how to ...
20
votes
2answers
12k views

What is the difference between DH and DHE?

I have been reading Bulletproof SSL and TLS Diffie Hellman is a key exchange mechanism, in which each of server and client share secret i.e. gx and gy respectively with each other where g is ...
1
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0answers
91 views

DTLS and Ephemeral Diffie-Hellman [duplicate]

In the DTLS handshake, the two parties involved in the communication must authenticate each other by means of certificates, and after that they perform an ephemeral Diffie-Hellman key exchange, with ...
5
votes
1answer
742 views

Is OpenSSL generating Diffie-Hellman parameters that are safe for use in TLS or SSH servers?

I would like to generate Diffie-Hellman parameters on a Debian GNU/Linux "Jessie" 8 with OpenSSL. Lets assume the system CSPRNG was seeded with some real random data. On such a system, is the result ...
8
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2answers
5k views

In Ephemeral Diffie Hellman Key Exchange - what is actually ephemeral?

Just starting to learn about Diffie-Hellman, and it seems simple enough, but I am struggling to find any resources that explain in an Ephemeral Diffie Hellman Key Exchange, what it is that is actually ...
1
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3answers
1k views

Using a stolen certificate on a server

Yesterday I asked the following question regarding what would happen if you placed a stolen certificate on your own server and edited the 'host' file so that the DNS name matched: Could a stolen ...
10
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3answers
1k views

What DH Group size do TLS Ephemeral DHE ciphers use?

In SSL/TLS, the Client and the Server have the option to use an Ephemeral Diffie-Hellman exchange to establish a shared secret for which to seed the ensuing Master Secret and Session keys. In the ...
-4
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2answers
172 views

Does SSL doesn't work without a secondary Symmetric/Asymmetric session key?

I keep reading that Symmetric session key is used in SSL after handshake only for faster performance but isn't true a secondary session key either Symmetric or Asymmetric key generated by the client ...
1
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2answers
3k views

What algorithm should I use to avoid the error “ERR_SSL_WEAK_SERVER_EPHEMERAL_DH_KEY”?

I got a CA cert by submitting my CSR from GoDaddy, after applying a certificate to my Tomcat web server. When I access my website using Chrome or Mozilla I face the error: ...