All Questions
Tagged with secure-channel or transport-security
66 questions
0
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1
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70
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Is ECDH still secure if I embed the server public key?
I'm pretty new to the concept of key exchange.
Diffie-Hellman does not have authentication, so it makes no guarantees on who is the other party of the connection.
Both key pairs (client/server) need ...
- 103
0
votes
0
answers
29
views
Signal's X3DH Protocol - what is Alice's ephemeral key? Is the previous ephemeral key used in the next message's run? Are one-time prekeys signed?
In the Signal Protocol and X3DH Protocol:
https://signal.org/docs/specifications/x3dh/
I have a few questions:
1. In section 3.3. "Sending the initial message", it says:
Alice verifies the ...
1
vote
0
answers
69
views
secure channel for sending partial private keys!
In certificateless cryptography, the KGC must ensure that the partial private keys are delivered securely to the correct entities.
So my question is how KGC can send these keys secretly?
In the other ...
- 31
5
votes
0
answers
113
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Most simple transport encryption for link-constrained environments
What is the most simple, but yet well-known "protocol" to protect a unidirectional channel over air?
Requirements
The protocol should provide common properties like privacy, integrity and ...
- 576
1
vote
2
answers
163
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Is this self algorithm made private key for Diffie-Hellman key exchange secure
i created a function in javascript that creates my a for the DH exchange like this:
...
1
vote
1
answer
51
views
Security of keys that are as long as the data
If both communicating sides end up with the same secret 3000-bit key, is it enough to XOR each byte of the messages with each byte of the secret key to make it secure?
Wikipedia says it is, but I ...
- 159
4
votes
1
answer
251
views
Secure channel: Is there a assumption in an MPC protocol that the communication between different parties is secure?
If we should consider that in an MPC protocol, the confidential messages communicated between two parties can be eavesdropped on by adversaries? If so, should we build a secure channel for that?
- 137
0
votes
1
answer
54
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Does TLS convert individual messages to ciphertext? If the network is breached, is the data exposed?
As far as I understand it, TLS creates a tunnel or channel or secure connection between the parties right? Where everything is protected? But hypothetically if the network gets breached, would the raw ...
- 35
2
votes
1
answer
304
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Is there a benefit to "double encryption" when it comes to attacks analyzing attempted decryption results?
This is a beginner's question related to general security, but it fits cryptography exchange because it's more specific to the action of cryptographic attacks and how they work.
Assume the following ...
- 199
-1
votes
1
answer
94
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How much security does using TLS provide?
If someone tells me their service uses TLS 1.2 or higher, how much 'guaranteed' security does this provide?
Is it possible to correctly claim to be using TLS 1.2 or 1.3 and still be insecure? For ...
- 125
1
vote
1
answer
94
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5bit ASCII armor with FEC?
For transmitting a ciphertext (or any other binary data) over means which only support 5bit ASCII/Baudot characters (for example morse code or RTTY) I am looking for a way to armor my data and have it ...
- 163
1
vote
0
answers
21
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Technological based solution needed for a real world problem of transferring a physical object between two untrusted parties [closed]
Suppose I have a physical object A. Another person also has some rights over the object A. After some litigations, a schedule has been made under which object A will be passed for some time to the ...
- 111
0
votes
0
answers
74
views
Securely transmit signed token (e.g., JWT) over insecure channel
Apologies if this is already answered somewhere, but I could not find it.
I have a setup where a client has a JWT (RSA- or ECDSA-signed), and needs to prove that fact to the peer which issued the ...
- 1
1
vote
1
answer
2k
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Zerologon question - AES-CFB8
I was reading the zerologon whitepaper by secura named:
Unauthenticated domain controller compromise by subverting Netlogon
cryptography.
I'm trying to understand the zerologon attack. The issue is ...
- 23
3
votes
1
answer
544
views
Does using Noise asynchronously weaken its security properties?
Can Noise be used asynchronously without weakening its security properties?
Specifically, there are two users, A and B, who communicate asynchronously by leaving messages for each other on an ...
- 105
-1
votes
1
answer
74
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Strangers cryptographically agree on secure video channel using information over insecure channel
Alice and Bob know nothing about one another, and talk for the first time on a video channel that they are not in control over and that might be compromised. They want to create a new secure channel, ...
- 1
3
votes
1
answer
1k
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SCP03 - Does it always to depend on pre-provisioned static keys?
I am trying to understand Secure Channel Protocol 03 from specified by Global Platform and have seen a few implementations. From the standard:
Session keys are generated to ensure that a different ...
1
vote
0
answers
42
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How does one ensure that a handshake protocol is secure assuming all underlying cryptography used are secure
Suppose one have to design handshake protocol using known secure cryptographic algorithm. The designer of implementer can assume that crypotography is secure but how would they ensure protocol itself ...
0
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0
answers
98
views
Interactive ECDHE Authentication With Numeric Code
Trying to simplify my question, keeping only core concepts.
Proposed solution:
Both user devices generates ECDHE key pairs. Send pub keys to each other. Generate shared secret.
Device that requests ...
0
votes
0
answers
37
views
How to protect traffic metadata from a malicious cloud provider?
What can be a theoretical and efficient way of protecting traffic metadata (packet size, timestamps, packet count) of enterprise when traffic is redirected to the SGX enclave residing in a cloud ...
- 21
0
votes
1
answer
47
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TLS handshake with client later on acting as a server
Is it possible that a client which gets the Digital certificate of the Server during the TLS handshake then acts as a server? Because a server only needs to have a valid digital certificate which it ...
- 3
1
vote
0
answers
49
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Does SET in any way use SSL?
I just started a course in web security, and I was just wondering quickly if SET in any way would use SSL? I noticed it was developed in part by Netscape. But all I can find is comparisons between the ...
5
votes
3
answers
1k
views
Nonce-misuse-resistance scheme applied after the fact to AES-GCM for defense in depth?
This is a follow-up to a previous question about encrypting IV/MAC results from AEAD ciphers.
I have a system I'm working on that needs to use standard (NIST/FIPS) cryptography, at least for its ...
- 906
1
vote
1
answer
91
views
Secure Communication
Focus:
I have to design a secure keep alive communication protocol and was wondering if it was necessary to sign the ciphertext after the session key has been generated as an attacker will not know ...
- 13
1
vote
1
answer
353
views
What is the "single-letter characterization of the secrecy capacity"?
I'm reading a paper [1] in which secrecy capacity are being discussed under the following terms:
A single-letter characterization of the secrecy capacity that holds for the general case remains ...
- 121
0
votes
1
answer
61
views
Security of HOTP over an unencrypted channel for controling an actuator
I have a simple on/off actuator that I want to control remotely. I want to use available hardware: a pair of microcontrollers connected to a pair of wireless transceiver modules.
Can HOTP algorithm ...
- 623
0
votes
1
answer
510
views
Understanding hybrid cryptography's concepts: signing and CA
After learning about symmetric encryption, public-key encryption, one-way hash, digital signature and digital certificate, I was tasked to think of an imaginary hybrid cryptosystem. I was thinking ...
- 103
2
votes
1
answer
154
views
Generate a per data shared secret vs per session
I have read about SSL that they persist the shared-secret for the entire session. However, someone in stackoverflow suggested a way of generating a shared secret for each data to send and then send ...
- 123
0
votes
1
answer
262
views
What attacks does future secrecy protect against?
Consider messaging between 2 parties. A sequence of messages are exchanged between the parties using encryption. We consider an attacker that has at a minimum a log of all the (encrypted) messages ...
- 115
2
votes
1
answer
226
views
why do we asume that in the registration process communication is over the secure channel?
I was reading some research papers and saw that in Registration phase/process it is always assumed that communication is over the secure/private channel, whereas, all of the phases communication is ...
- 21
1
vote
1
answer
3k
views
What is Perfect forward secrecy?
I have read that when a user contacts an entity like a bank, it creates a pre-master key and then selects a master key for subsequent communications.
Can the lack of PFS, create a security flaw if ...
- 247
4
votes
1
answer
442
views
Does it make sense to have long SSH Key with shorter Passphrase?
If we encrypt our data with a longer SSH key which is protected by a shorter passphrase (with a decent entropy), then the limiting factor is entropy of the passphrase. So why do we use a longer key at ...
- 143
3
votes
1
answer
2k
views
Key transport vs key encapsulation?
What exactly is the difference between key transport and key encapsulation? Either they seem to be used interchangeably or I'm mixing stuff up.
- 357
0
votes
1
answer
173
views
Secure communication channel recommendations
I'm working on a cryptography-related project, which uses ECC (elliptic curve cryptography). And one of the things that I need is a "secure" communication channel for two entities.
I need someone to ...
- 359
3
votes
1
answer
641
views
Establishing a shared secret over a unsecure channel
Is it possible to establish a shared secret between two devices if the devices have no prior knowledge and no secondary secure channel to exchange information?
Assume a Dolev–Yao model for the ...
- 133
4
votes
1
answer
1k
views
TLS: Risks of using a NULL cipher with encryption implemented in application?
We have a browser-launched JNLP/WebStart application that is no longer able to establish client-server CORBA/IIOP communications across TLS 1.0/1.1 due to relying on a cipher suite that uses an ...
- 41
18
votes
8
answers
23k
views
4
votes
2
answers
1k
views
Signal Double Ratchet - How can Alice send 2+ messages in the beginning of the Signal Protocol?
I'm studying about Signal Protocol and I had a doubt in Double Ratchet Algorithm. This section describes how to derive the receiving and sending key messages.
Alice is initialized by Bob public ...
- 159
3
votes
1
answer
572
views
X3DH Protocol - How can the receiver calculate the Shared Key?
I'm reading about Signal Protocol and X3DH Protocol. In the X3DH Protocol, Alice sends a initial message to Bob encrypted with a Shared Key(SK). This SK is calculated using (this section):
...
- 159
1
vote
1
answer
282
views
There is a protocol similar to SRP but where a part of the secret is stored on the client side?
SRP is very useful but if our DB is leaked, an attacker could brute force a user's password with his associated salt/verifier found in the DB. I'm searching a solution to prevent this.
My first idea ...
- 51
5
votes
2
answers
3k
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X3DH protocol - What are One-time prekeys for?
I'm reading about Signal Protocol and this protocol uses the X3DH Protocol to establish a shared secret key between the two parties but I couldn't understand why we use one-time prekeys in the flow. ...
- 159
1
vote
1
answer
114
views
Is there an escrow-like mechanism that doesn't involve a trusted 3rd party?
We know that escrow mechanisms are easy to implement when it involves a trusted 3rd party. For example if A and B don't trust each other they can simply send their goods to C whom they both trust. ...
- 461
2
votes
0
answers
96
views
What's a good security schema for many to many communication?
Assuming you have a "typical" group chat-room, with n participants connected together by a server (the server handles message routing).
Would be a good security schema which would allow for encrypted ...
- 121
2
votes
2
answers
2k
views
TLS Finished message: is it MAC or HMAC
In several academic literature, the term Finished MACs is used frequently. I wonder, is it really a MAC or HMAC? I am looking at literature in TLS 1.2 vs. TLS 1.2 specs. The specs of TLS 1.2 Finished ...
- 503
5
votes
1
answer
2k
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TLS1.3 encrypted handshake
I read that TLS 1.3 supports encrypted handshake. Is it achieved using encrypted_extensions?
Does it mean that the records which contains handshake messages are encrypted/protected from the point of ...
- 425
3
votes
1
answer
647
views
What's dh-composite test on badssl.com?
The site badssl.com provides examples of bad (red icon) and good (green icon) uses of TLS for the purpose of testing TLS implementations. I'm a bit confused by the test called dh-composite. This ...
- 41
15
votes
4
answers
14k
views
Best choice out of these six TLS cipher suites
I have a small embedded platform that supports 6 TLS ciphers. Is there a good/better/best one to chose?
I was looking around on the web for some kind of rating system or list of ciphers that have ...
- 153
2
votes
1
answer
296
views
Any case that can require to encrypt a certificate revocation list before distribution
As far as we know certificate revocation lists (CRLs) include public information so they do not have to be encrypted before distribution.
Is there a case that can require to encrypt it before ...
- 181
3
votes
3
answers
258
views
DIY message level security?
This might be in danger of being too elementary a question for this community but I'm hoping for expert help:
Assuming that TLS is not enough to protect messages transmitted between a client and a ...
- 139
2
votes
1
answer
133
views
Insecure third party connection
My organization processes some PII data and shares it with an outbound connection (outflow only) that is a third party. The data transfer transactions occur without human intervention. That outbound ...
- 21