Questions tagged [key-exchange]
For questions relating to protocols for distributing public keys, and / or establishing session keys with another party. Examples of key exchange protocols include Diffie-Hellman and IKE.
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does a public key work with all encrypted programs
let us say, I use program "x" for my e-mail security. through them I have a public key and a private key. My friend uses program "y" for their e-mail security and consequentially have a public key and ...
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How would I give an encryption key to only one person?
Let's say I have an encrypted message. I want to make it so that someone is able to decrypt it. The only way of giving it to them is online. For the purposes of this question, I can't call, mail or ...
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Any Suggestion Exchanging shared key between process via port in untrusted machine (infected my malware)?
I am trying to get shared key between Firefox extension and a java program running in same machine. I am communicating both application via socket.
My assumption is that malware is running in ...
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Why Qualys SSL Server Test is giving me 80 and not 100 in Key Exchange?
My openssl ciphers -v 'CIPHER' output is the following:
ECDHE-ECDSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=ECDSA Enc=AESGCM(256) Mac=AEAD
ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx=ECDH Au=RSA Enc=...
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Optimal variable sizes in the Secure Remote Password protocol
I am implementing the Secure Remote Password protocol:
U = <username> -->
<-- s = <salt from passwd file>
a = random()
A = g^a %...
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Implementing Secure Remote Password: Constructing the verifier
The SRP protocol as described in RFC 2945 generates the password verifier:
x = SHA(<salt> | SHA(<username> | ":" | <raw password>))`
v = g^x % N
I have three questions: ...
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Using Secure Remote Password without sending the username in the clear
To initiate a key exchange using the SRP protocol the client sends the username so the server can look up the salt and password verifier. Is there a simple way to change this so that an evesdropper ...
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Using Secure Remote Password without embedding the modulus
The SRP protocol as described by the author assumes that the large safe prime modulus and generator are embedded into the client and server rather than being transmitted as part of the protocol. ...
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ECC Brainpool Standard Curves and Curve Generation with Bouncy Castle which seed to use?
I want to implement a ECC Key Agreement with a Brainpool curve brainpoolP512r1 or brainpoolP512t1.
I'm not clear about whichseed value to use (and how).
In this document http://www.ecc-brainpool.org/...
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Is there a way to negotiate a secret between 2 parties with no prior knowledge?
Is there a way for 2 parties to negotiate a shared secret (for example, a session key) without having a pre-shared knowledge?
SSL does this by using asymmetric encryption. Is there any other way to ...
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How do I share my S/MIME public key?
I have setup S/MIME encryption for my email address, and I'd like to allow people to download the public key from my website, rather than having to first receive an email from me.
I want the public ...
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Can manual hash verification defend against a DH MITM attack?
I understand how DH key exchange is vulnerable to a MITM attack.
When Alice sends Bob g, p and her public key, if she also sent a value H that was a hashing of the values g,p, and public key all ...
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Which authentication at the end of the Secure Remote Password protocol?
For the the client and server to prove to each other that they have the same premaster shared key, the original author suggests this:
M = H(A | B | K) -->
<-- H(A | M | K)
The ...
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How do key servers resolve conflicts?
According to the PGP network FAQ
While a number of key servers exist, it is only necessary to send your key to one of them. The key server will take care of the job of sending your key to all other ...
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Would a predefined shared secret key be good here
I'm a software developer working with hardware devices that are deployed on the field. Every now and then, I would need to update the hardware's firmware (upgrades, patches, etc)
I'm thinking of now, ...
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Why was ECMVQ dropped from NSA Suite B?
I've found two mentions on Wikipedia that Elliptic Curve Menezes–Qu–Vanstone (ECMVQ) was dropped from NSA's Suite B however they seem to imply different reasons. One mention is preceded by talk of how ...
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Is there a known vetted alternative to this key-exchange protocol?
I have three participants:
A client A in possession of the public key Kpub
A login server S in possession of the private key Kpriv
Game servers B (B1, B2 etc)
S and all B may share a finite number of ...
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Any obvious flaws in this protocol?
Are there any particular flaws in this protocol?
(Yes I know about SSL)
Three participants:
Login Server LS
Game Server GS
Client C
Asymmetric key-pair Kpriv Kpub
Shared 128bit secret key Ksec
...
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Which is better for SSL: TLS_EDH or TLS_SRP?
DH is vulnerable to a man-in-middle attack due to no server authentication; and RSA does not have forward secrecy.
People suggest used Ephemeral DH but what are the differences between Ephemeral DH ...
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Why should an IKE responder change the cookie secret 'frequently'?
IKEv2 has the concept of a COOKIE mode, to attempt to prevent state exhaustion from floods of initiation requests from non-existent IP addresses:
Two expected attacks against IKE are state and CPU ...
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Understanding a key establishment protocol
I'm studying a one-pass key establishment protocol.
Let be A client and B the Server.
A sends to B:
E_w(t,b,k)
where t is a timestamp requested for freshness, k is the ephemeral key that will be ...
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Key distribution and key exchange for simple secure FTP implementation
I'm developing a simple secure file transfer protocol for a University project using openssl.
I have a Client (let be C) and a Server (let be S).
C will send to S messages like get, put, cd, … and S ...
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The request was aborted: Could not create SSL/TLS secure channel Exception
Let me explain my situation.
I created a self-signed certificate and installed it in the Trusted Root Certification Authorities section in MMC.
I then created two certificates using the self-signed ...
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Diffie Hellman - how large should the random number be?
When using the Diffie Hellman exchange with the second Oakley group 1024 bit Prime per RFC 2409 (*), how large should the random numbers generated by both sides be?
In RFC 2631 this is called the ...
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Picking exponents for Diffie-Hellman
I'm taking a class on Cryptography and the professor mentioned that given mod N and base g with a certain order, you should pick powers m and n such that they create a certain property with the order ...
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Mutual Anonymity in key exchange
If Alice (sender) sends a private message embedded with public key of the Bob(recipient) through onion network, so in this key exchange, does Bob remains anonymous to Alice as Alice knows about the ...
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Cryptography key gathering tool [closed]
I am wondering if there exist a tools which can return the value of the one of the private key if the following are known:
1) Encryption Algorithm
2) Public key
3) Plain text
4) Cipher text
Or may be ...
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GPG advantages / disadvantages, is it useful or secure? [closed]
I thinking about GPG, is very widely used, but is secure? Why and where we using GPG?
I found an article from 2002, but is very old.
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Does the hash change the security of the Secure Remote Password protocol?
I'm implementing the Secure Remote Password protocol, and similar to this question, I'm wondering if I can use the SHA-512 hash function instead of SHA-1 currently being used. Would this help improve ...
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Secure Encrypted Chat Protocol [duplicate]
Possible Duplicate:
Is there a way to negotiate a secret between 2 parties with no prior knowledge?
Imagine two clients who want to establish a secure connection over a server. Both clients have ...
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Given a large enough sampling of public keys could one begin to identify a private key?
For example, an ISP or government capable of tracking millions of keys being exchanged. Would that provide a sample large enough to be able to identify the private key on either end?
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Are SSH packets encrypted even before new keys are sent?
What format does SSH use to exchange (encrypted / plain) packets before new keys are derived? SSH Document says that after key exchange, client and server use negotiated algorithm to encrypt the ...
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Are there flaws in this simple key exchange?
I'm reviewing for a computer security exam. Here is a simple scenario:
Suppose that someone suggests the following way to confirm that the two of you are both in possession of the same secret key. ...
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In the Diffie-Hellman key exchange, how is the shared base key 'p' known and how are A and B, protected from Eve?
I'm trying to wrap my head around Hellman, Diffie, and Merkle's key exchange design, but after reading the Wiki article about it, I can't figure out how the commonly known factor ('p', I think) comes ...
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Diffie-Hellman key-exchange: securing prime and base
As we know DH algorithm based upon 2 large prime numbers, which are used to be called as prime and base
I am writing app which implements DH key exchange algorithm. From security point of view should ...
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Secure device pairing protocol
I need to implement secure pairing between two devices based on a short shared PIN code with no trusted third party. If you think about the way bluetooth devices pair you won't be far off -- my ...
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Establish a secure channel with mutual authentication given pre-shared public keys
Suppose I have a system whereby parties are identified by their public key (with some pre-selected asymmetric key algorithm). Suppose I have a party PUB1 which wants to establish a secure channel with ...
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Inner Workings of Public Key Encryption
After watching this video explaining PKE with tennis balls (interesting), it left me with a few particular questions that I'm having trouble finding answers to:
I assume that they keys used to unlock ...
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TLS server key: possible to sign another TLS server key?
If I have a valid (verifiable) certificate C_K_s that links the server key K_s to "www.example.com", is it possible to :
use K_s to sign K_d, and let S_K_d be this signature
use K_d as the TLS ...
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Which cipher suites with AES cipher provide forward secrecy?
Does standard AES with RSA (reported by Opera as TLS v1.0 256 bit AES (1024 bit RSA/SHA)) provide perfect forward secrecy?
Which SSL3.0 and TLS1.0 ciphers do provide forward secrecy?
Which ciphers ...
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Is it possible to have a key for encryption, that cannot be used for decryption?
For example, a server might have some encrypted logs or storage or whatnot, that would only be used for reference later. This way even if the server is hacked, everything is still OK until the hacker ...
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Is 1024bit Diffie Hellman key exchange secure?
My system uses AES-256, 4096bit RSA CA key and 2048bit RSA keys for servers together with SHA-256 signing.
Does using 1024bit DH key exchange lower its security?
I read on one mailing list that ...
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Theorical question on encryption methods [duplicate]
Possible Duplicate:
Encryption strategies for multi users access in production systems
I would like to develop a service on wich clients would connect and retrieve informations. These ...
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Differing scrambling parameter generation methods in Secure Remote Protocol
RFC 2945 (The SRP Authentication and Key Exchange System) states,
The parameter u is a 32-bit unsigned integer which takes its value from the first 32 bits of the SHA1 hash of B, MSB first.
whereas ...
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How to exchange RSA public keys safely between two parties?
How to exchange RSA public keys safely between two parties via internet?
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distributing files to VPN partners
suppose i've created VPN certificates for a certain VPN-RoadWarrior-Client, expressed in the files VPN-RoadWarrior-Client.key and VPN-RoadWarrior-Client.crt*, however VPN-RoadWarrior-Client is ...
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