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Questions tagged [man-in-the-middle]

A man-in-the-middle (MITM) attack is an active attack where the attacker is able to interpose himself between the sender and receiver. The attacker may monitor and/or modify some or all of the messages sent between the two endpoints.

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Is the MITM protection provided by BLE LESC passkey mechanism bidirectional?

I'm trying to understand whether the passkey mechanism described in BLE LESC pairing provides bidirectional MITM protection. As far as I understand, A and B will generate the same shared secret using ...
cheapjuice's user avatar
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Dealing with MITM attack in e-voting systems

I've read many e-voting papers that use El-Gamal scheme which I recall is vulnerable to man-in-the-middle attack, yet I find no discussion or even mentioning of it in those papers. -Does anyone knows ...
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Questions about TLS 1.3 inspection with commercial middleboxes

i'm trying to learn how commercial (for example PaloAlto or Fortigate) middleboxes intercept and decrypt TLS 1.3 traffic. To do that I started observing the TLS traffic between the client, middlebox ...
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How two secure elements can safely authenticate each other without a third party?

Assume there are multiple secure elements, and also multiple man-in-the-middle or malwares. How can any two secure elements authenticate each other without a third party and hard coding something in ...
MJay's user avatar
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How can I impersonate Bob without creating a new session

Good morning, I've been struggling with this protocol for the last few days and I'm out of ideas now. The goal is to impersonate Bob by just modifying or dropping packages. The attacker(me) is a Proxy ...
Goel77's user avatar
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Double Ratchet Algorithm: Active Man in the Middle Attack without Root-Key or Ratchet-Key

I am currently studying the Double Ratchet Algorithm from Signal (link to the documentation). I stepped over a security issue which I was not able to find that it was mentioned anywhere. I assume that ...
p_1092131280's user avatar
2 votes
1 answer
120 views

Does having more than one HMAC provide more information to the attacker?

Suppose $N$ many messages has been sent from $A$ to $B$ in this format: $\operatorname{HMAC}(K, C(i)) \mathbin\| C(i)$. Where $C(i)$ is some cipher-text encrypted with some secure algorithm using ...
CuriousCrypto's user avatar
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Can attacker eavesdrop on the user credentials during WPA2 (802.1X) handshake?

In a WPA2 (802.1X) scenario, there are 3 entities -> Supplicant (client), Authenticator (router) and Authentication server (Radius server). Radius server performs the authentication process and, as ...
hexHujer's user avatar
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1 answer
467 views

Defending MITM attacks during key exchange

As far as I know, key exchanging algorithms are vulnerable to an active MITM attack. Let A (Alice) and B (Bob) be parties with no secret information. An adversary C playing man-in-the-middle ...
imamangoo's user avatar
2 votes
3 answers
170 views

Can a man in the middle tell what kind of encryption you're using from a key exchange?

Encryption schemes typically are built on the idea that even if a man in the middle attacker knows exactly what kind of encryption you're using, they cannot decrypt your messages without the key. ...
Beefster's user avatar
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Can a MITM during Diffie-Hellman key exchange manipulate both sides to generate symmetric secrets?

Is it possible for an attacker on a Diffie-Hellman key exchange to manipulate both sides in a way so that the secret generated on each side is identical? Or put differently, would it be possible to ...
smatt's user avatar
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3 answers
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Public-key/asymmetric encryption where you can only leak the decrypted message by leaking your password

A bunch of friends are using public-key encryption to send encrypted messages to each other using an open public forum. I.e. each friend has a public key (which you can use to encrypt messages for ...
chausies's user avatar
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1 answer
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Proving you're from the year 2069

Just a question I thought of while playing an amazing game about time travel (13 sentinals aegis rim). What are the most bullet-proof cryptographic methods for proving you've come from beyond a ...
chausies's user avatar
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Version rollback attack prevention in TLS 1.2?

Are there any methods to prevent version rollback attack while using TLS 1.2 (apart from disabling lower versions)? I've read about how TLS 1.3 provides a downgrade protection mechanism which is ...
bobthebuilder's user avatar
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168 views

Can Bob and Alice do an authenticated Diffie–Hellman key exchange if Bob only knows the hashsum of Alice's key?

Tor vanilla bridges look like this: Bridge x.x.x.x:1234 9DD03662B50FEDBF6F8D5630CB86D7E8CE4F4432 It's only the IP/Port and a hash of the key. Can Bob and Alice do an authenticated Diffie–Hellman key ...
phantomcraft's user avatar
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2 answers
248 views

Encrypting with nonces in IKE

In IKE exchanges, first messages sent unencrypted and unauthenticated. For authentication, messages sent encrypted with nonces. If a man in the middle is eavesdropping this conversation, he/she will ...
hadz's user avatar
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Are PGP messages susceptible to man-in-the-middle attack?

Say Alice wants to send a PGP encrypted message to Bob. She generates a symmetric key, encrypts it with Bob's public key, and sends both the message and the encrypted symmetric key to Bob. Then Bob is ...
Lee's user avatar
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2 answers
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Understanding MITM in an example authentication protocol

Imagine that we have a protocol like this: B -> A: RB A -> B: {RB,B}K Goal: authenticate A to B K: a shared key between A and B {}K: encrypting by K After receiving {RB, B}K by B, B is able to ...
Hedeesa's user avatar
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Proof that exchanged variable was not modified with MITM

If I understand correctly, the core of man in the middle attack is in being able to replace an exchanged variable (public key) with another. Hence to detect a MITM one needs to check if the exchanged ...
user369070's user avatar
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Simple Key Exchange, One Server

I am trying to better understand how TLS works. I understand in the normal use case you need various random values generated and used in the key exchange, to prevent some MITM reusing a previous ...
Bondolin's user avatar
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Read ECDHE traffic with Wireshark or the like

There is some https traffic from a specific server (which I have the certificate and private key) that I need legitimately be able to read. This traffic doesn’t come via browser so besides the ...
Nacionarte's user avatar
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1 answer
60 views

Domain Keys Identified Mail (DKIM)

If a company uses Domain Keys Identified Mail ("sender adds a special signature which includes author name / date signed by RSA Private Key. Receiver verifies the signature by looking up the ...
James's user avatar
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2 votes
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Why is DH key exchange still useful, if a public key certificate is used?

EDIT: According to Gilles's comments and fgrieu's answer below, I would like to summarize what I have learned, and what's still needs explanation: DHKE is necessary for forward secrecy even when PKI ...
xrfang's user avatar
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Method to mitigate MitM attack for DH key exchange

Plain DH key exchange protocol is vulnerable to MitM attack. I checked the SRP (RFC 2945) but did not fully understand why it can help. I thought of a fix to mitigate MitM problem by using a pre-...
xrfang's user avatar
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TLS 1.3 Handshake - Usage of MAC and Digital Signature for CertificateVerify and Finished Message

I was wondering, why the TLS 1.3 handshake employs two different 'messages' that compute an authentication code over the whole handshake. As far as I understand, the CertificateVerify "message&...
Bastian's user avatar
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2 votes
1 answer
171 views

Dishonest verifier running a concurrent zero-knowledge protocol

Suppose Alice and Bob are engaged in the graph 3-colorability Zero-knowledge protocol in which Alice permutes a coloring $\varphi:V\rightarrow \{1,2,3\}$ for a graph $G(V,E)$, and then sends a ...
Mateo's user avatar
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-1 votes
1 answer
97 views

Can X3DH algorithm implementation be avoided to thwart Man-in-the-Middle Attack during End-to-End Encryption with Diffie-Hellman Algo, When using SSL

For End-to-End Encryption in chats using Diffie-Hellman Algo the concept of Extended Triple Diffie-Hellman (X3DH) is used to prevent Man-in-the-middle attack (MITM) (courtesy: https://www.qed42.com/...
Alok Pabalkar's user avatar
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Does a man-in-the-middle attack apply in this scenario?

Disclaimer: I am aware that the question's title does not adequately describe what I am asking, but it is the best I could come up with. Any improvement is welcome. I am a university student studying ...
riverwastaken's user avatar
14 votes
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The backdoor of Telegram on Diffie-Hellman Key Exchange and possibly other examples?

Diffie-Hellman Key-Exchange (DHKE) should be used carefully during the end-to-end encryption. A man-in-the-middle (MITM) attack is possible. Standard DHKE The simple protocol on the multiplicative ...
kelalaka's user avatar
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2 votes
1 answer
98 views

MitM with regard to unauthenticated clients

I'm trying to understand how man-in-the-middle attacks are prevented during key exchanges, and am confused by this Wikipedia statement: Use of mutual authentication, in which both the server and the ...
Witness Protection ID 44583292's user avatar
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1 answer
410 views

Possibility of Man-in-the-Middle on X3DH

I'm reading about the security of the Signal protocol (used in WhatsApp) and in particular, the X3DH part used to establish authentication, all papers seem to gloss over Man in the Middle attacks. Is ...
CryptoCurious's user avatar
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237 views

Diffie-Hellman man-in-the-middle attack

Diffie-Hellman Key Exchange Basic Protocol: Let G be a cyclic group of order $n$ and generator $g$. Alice chooses $a \in \{0,\ldots,n-1\}$ and Bob chooses $b \in \{0,\ldots,n-1\}$. ...
Leafar's user avatar
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1 vote
1 answer
80 views

If two hosts are using a transparent IP level authentication and encryption, is their communication subject to both MITM or replay attacks?

Encryption process for any outgoing packet to the specified "remote IP": -original payload P is encrypted (the bytes after the IP header) using RC4 with the preestablished key ...
Koolz's user avatar
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0 answers
33 views

Can Alice encrypt a message to Bob without hiding anything from Eve? [duplicate]

I know that if Alice and Bob both have secret-public key pairs, they can use RSA for example. If we remove the possibility that Alice can know anything which Eve doesn't (ie Alice's secret key), is ...
zabop's user avatar
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1 vote
1 answer
1k views

Triple Diffie-Hellman and MITM

While reading about Triple Diffie-Hellman, I was wondering how it can prevent MITM if the server decides to spoof key sets. For example, Alice and Bob are connected using a server. Alice ----- ...
Rahul's user avatar
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1 vote
0 answers
94 views

attacks and defenses on multi party Diffie-Hellman protocol

I tried to create a 4 partied Diffie-Hellman implementation for 4 people using its cyclic group property. However, I am not sure regarding those 2 issues, and would appreciate if you could elaborate ...
Crypto123's user avatar
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0 answers
40 views

Server stored, encypted messaging app

For my personal research, I have to create a messaging app, but security is only important part of application, security from MITM (man in the middle attack), at device end, and at server level. (note:...
Jay seen's user avatar
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3 votes
1 answer
230 views

How is Diffle Hellman with RSA immune to man in the middle?

Alice and Bob want to exchange keys, Alice sends his half (the public key of the ephemeral key pair) signed with his private key and makes the public key available. Eve is bridging the connection so ...
Gaurav Pant's user avatar
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0 answers
237 views

How does DHE-RSA work and why is PFS guaranteed?

How does it work and why is forward secrecy guaranteed? I understood that it is not susceptible to a man-in-the-middle attack by using certificates in the beginning.
NightRain23's user avatar
0 votes
1 answer
92 views

Observing cipher suites and certificate algorithms without man-in-the-middle

I manage a proxy server. Is it technically possible to observe and determine which cipher suite is selected between end points (client and server) without changing their SSL certificate, without ...
Kibele's user avatar
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0 votes
1 answer
46 views

Is it necessary to have a certificate when we use TLS

When we say a communication is secured by the latest version of TLS, can we say that Man-in-the-Middle attack is not possible? Do not consider the situations that we can down grade the communication ...
Reza's user avatar
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1 vote
1 answer
246 views

Prevent a Man-In-The-Middle attack whilst transmitting a PSK for first time

I'm developing a network where two parties that want to join both compute ephemeral ECC keys for a key exchange, to create an encrypted connection. I plan to authenticate these keys by signing them ...
SamG101's user avatar
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5 votes
3 answers
7k views

Diffie-Hellman algorithm and MITM attack

How does the Diffie-Hellman algorithm prevent MITM attack? I have tried to search about it but i couldn't find any understandable reasons.
Mas HJ's user avatar
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0 votes
1 answer
1k views

How is STS more secure than regular DH

I'm trying to understand the STS protocol (using the wikipedia page as source), but I don't see how this protocol is any more secure than DH regarding man in the middle attacks. If Alice and Bob don'...
Vlaya's user avatar
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1 vote
1 answer
309 views

How are public keys securely and reliably obtained across the internet?

I've just decided to start learning all about PKIs, and I have come across what seems like a paradox. When fetching a public key from either a server or a CA, how can we be sure that the public key ...
invertedPanda's user avatar
0 votes
1 answer
231 views

Entity authentication protocol by encryption

I'm not a cryptography expert, so excuse me if the question seems very trivial. I need to know if this protocol is secure against a MiTM attacks and ensure a safe entity authentication method. We ...
thinker.92's user avatar
0 votes
1 answer
172 views

Is this man in middle atack possible in quantum cryptography? [duplicate]

Lets consider there is channel between Alice and Bob, sequered with quantum cryptography. To put it simple, Alice is left, Bob is right and the quantum states are 'up' ~ U and 'down' ~ D. Alice ...
user8426627's user avatar
2 votes
1 answer
339 views

Man-in-the-middle attack on text-book RSA PKE

I am attempting to solve the following problem: I know the following: 3 messages are being sent between Alice and Bob, all messages are encrypted with the known public key $(d,N)$: Alice sends ...
Gal Sheldon's user avatar
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1 answer
350 views

Needham–Schroeder fix by adding opponent's identity to the first message

Recap: Needham–Schroeder is as follows: $A \rightarrow B : \{A, N_a\}_{pk_B}$ $B \rightarrow A : \{N_a, N_b\}_{pk_A}$ $A \rightarrow B : \{N_b\}_{pk_B}$ Then, there is a MITM attack by Lowe ...
iesiyok's user avatar
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0 answers
161 views

How to decrypt plain text x using man in the middle attack

Suppose Alice want to share a plain text $x = 5$ to Bob; using RSA, DHKE, and El-Gamal. My question is if Man-in-the-middle attack is applied then weather oscar can compute/decrypt plain text in all ...
Hafiz Siddiq's user avatar