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New answers tagged public-key

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If you read all of the RF 8032 you will see that there is a compression (endcodings) of the points. def point_compress(P): zinv = modp_inv(P[2]) x = P[0] * zinv % p y = P[1] * zinv % p return int.to_bytes(y | ((x & 1) << 255), 32, "little") Compression just stores the sign and restores it back with this information def ...

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Are there any cryptographic primitives/protocols allowing the sender to signal to the recipient faster that the message is intended for them, yet not reveal the true recipient to everyone else and allow them to quickly skip trying to decrypt the message? It doesn't appear that the problem of recognizing the message (without leaking who the message is for) ...

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How this general kind of thing is handled today is with hybrid encryption. A symmetric key is generated and the message is encrypted with that. Then the symmetric key is key wrapped (encrypted) using the public key of each intended recipient. (Keep in mind that RSA can only encrypt small amounts of data.) This only encrypts the data once. You can make it ...

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encrypt with the private key, and decrypt with the public key That statement, and the very name privateEncrypt, is incompatible with standard terminology: "public" means known to all and opposes to "private"; and "encrypt" implies transforming some information $X$ into $Y$ in a way such that if $Y$ becomes public, $X$ does not. ...

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More incentive-based than crypto-based (anyway proposing it just because it means you are using someone else crypto ;-) ): append to the text going to be encrypted a reward, for example the privkey of a rich-enough Bitcoin UTXO, then monitor that UTXO. Of course to be effective you have to correctly value (from attacker POV) the "secret decryption"...

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Give each stakeholder a part of the secret key so that no subset of all intereested parties can decrypt the message. They all have to cooperate and share their parts in order to decrypt and they all have control over when they release their part to the others.

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Not using El Gamal. For any given El Gamal public private key pair, every pair of group elements $(a,b)$ represents a legitimate El Gamal encryption of some message. In other words, for any given $C_2$ there exists some $P'_2$ that encrypts to $C_2$ under the same public/private pair used for $P_1$ and $C_1$. If a different key pair were used, we would have ...

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Q : "Is the ad encrypted with his private key ..." A : indirectly, yes After some more thought, I can demonstrate a hybrid scheme based on RSA asymmetric cryptography: What is RSA encryption and how does it work? Lake '21. This proposed solution has significant faults, so don't even think about using it! More: What specific padding weakness does ...

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Chaum-Pedersen protocol tweaked with Sigma AND composition should do. The high level intuition: using Chaum-Pedersen protocol for DH-triple, one can prove knowledge of secret witness $\alpha$ in the following relation in (honest verifier) zero-knowledge:  \mathcal{R}:=\left\{((x, y, z), \alpha)\in\mathbb{G}^3\times\mathbb{Z}_q: \quad y=g^\alpha \land z=x^\...

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Interesting premise. Q : "Is the ad encrypted with his private key ..." A : no, I don't believe so Edit - To clarify, I entertained the possibility that the author meant to say "private key" in item #4, but once you consider the subsequent paragraph in the source (excerpt below), I don't think the ciphertext that describes the crime in ...

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Since Blockchain is a decentralized system, it has to stop malicious behaviour [which may just be disruptive if not benefiting the attacker directly] and collusion. Proof of work achieves that by introducing a very large computational cost. It also removes the burden on the nodes of checking transaction ordering. Also the code is running in parallel in ...

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In SIV type crypto-systems (like AES-SIV, etc), where initialization vectors are derived from the plaintext of messages, a timestamp can be concatenated with the plaintext to either potentially improve the cipher's nonce reuse/misuse resistance, or to reduce the likelihood that two identical plaintexts that are temporally separated will produce the same ...

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A large issue with questions like this tends to be the technical details, so apologies if I come across as particularly nit-picky --- I just do not know how to answer questions like this without pointing out the nits that need to be picked. at least if the activation function is continuous, could carry up to even infinitely many links with just changes in ...

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There are many ways to solve that problem. I would like to tell you my first ideas: Create a protocol, so that everyone shares the same key. With this key everyone can decrypt the file, write stuff, and the encrypt it again. It is a symmetric approach, but you public key infrastructure may be good to share the key (e.g. Diffie Hellman key exchange. This can ...

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