# Questions tagged [diffie-hellman]

The Diffie–Hellman key agreement is an anonymous, non-authenticated key-agreement protocol.

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### Encrypt messages for two-participants chat

I need a chat between two users and I obviously want to make it as secure as possible. I am, by no means, a cryptography expert, so I turn to you guys for some advice. Because I like the idea of ...
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### Finding $a$ in $g^a\bmod p$ in Diffie-Hellman [duplicate]

This might be a silly question but I am unable to wrap my mind around it. In Diffie-Hellman can we find $a$ when $A = g^a\bmod p$, given we know $A$, $g$ and $p$?
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### How does this libgcrypt elgamal decryption work?

Update: The question below was asked before I realized that this is being done to prevent a side channel attack: https://github.com/advisories/GHSA-5p8v-2xvp-pwmc What I am still curious about, is the ...
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### Trying out the small subgroup attack on a group of non-prime order using a simple additive group instead of an Elliptic Curve Group?

This is the attack I am talking about - Why are the lower 3 bits of curve25519/ed25519 secret keys cleared during creation? An elliptic curve group of order $8p$ where $p$ is a prime. Let $G$ be the ...
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### In a Diffie-Hellman key exchange Find this key and compute the shared secret key k

Hi I struggling to find the answer of my schhol exam, can anyone help me . In a Diffie-Hellman key exchange the multiplicative group of integers modulo p is used with the parameters p = 59, g = 3 mod ...
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I have a need for the following encryption properties: $f(g(v_\text{plaintext}) = v_\text{ciphertext}$ needs to be decryptable by $f^{-1}(g^{-1}(v_\text{ciphertext}))$ and $f$ and $g$ need to be ...