Questions tagged [libsodium]

"The sodium crypto library". A cryptographic multi-language-library with support for many modern cryptographic primitives, that is a fork of the NaCl library. The library focuses on providing easy-to-use cryptographic primitives.

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How to read libsodium's scalar from integer/bytes or NTL:zz

Hi I am new to lib sodium, may I ask that is it possible to get scalar of ristretto255 from integer/bytes or NTL:zz? Some thing as follows: ...
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Ed25519 and sealed boxes libsodium

Accidentally used ed25519 public key to create libsoidum_sealed_box. Is there any way to decrypt the data if the private key ed25519 is known?
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implementing pedersen commtiment using lib sodium

Hi I want to implement pedersen commitment ontop of lib sodium Below is what I am trying to do: comm1: m1G+r1H comm2: m2G+r2H comm3: (m1+m2)G+(r1+r2)H comm4: comm1+comm2 and comm3 should equals ...
3 votes
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Can I use Libsodium crypto_box_easy for signing with 32 byte keypair?

I have a chat system where multiple clients communicate securely using Libsodium authenticated encryption. Every client have their own 32 byte key pair. If two clients want to communicate they first ...
2 votes
2 answers
279 views

ECDH between identical public keys

We are using libsodium and regarding exchanging secrets we would like to use the so-called crypto_box (https://libsodium.gitbook.io/doc/public-key_cryptography/authenticated_encryption). Under the ...
2 votes
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What good elliptic curve uses a scalar field the size of the Ristretto255 group?

I am implementing Bulletproofs over Ristretto255. (I am using libsodium, so can't switch to another Elliptic Curve implementation.) I need to implement zero knowledge verification of elliptic curve ...
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Check if pubkey belongs to twisted Edwards25519

I want to check if some pubkey belongs to twisted edwards25519 (I guess this is used for ed25519 ?) The problem is that I have in theory some valid pubkeys like: ...
1 vote
1 answer
218 views

Simplistic double ratchet implementation

Would something like this be a reasonable way to implement the double ratchet with libsodium? The sodium port that I'm using is quite limited and does not offer a ...
63 votes
3 answers
29k views

Why Curve25519 for encryption but Ed25519 for signatures?

NaCl and libsodium libraries use Curve25519 for authenticated encryption (actually for sharing a key which is used for encryption) and Ed25519 for signatures. What is the purpose of using different ...
2 votes
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Why is there a slight mismatch most of the time in X25519 private keys depending on functions used, but public keys always match (same seed for both)?

I'm trying to wrap my head around going from a seed to a SigningKey, and also obtaining a ...
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1 answer
371 views

Does the libsodium sealedbox provide forward secrecy?

I am using sodiumoxide, a Rust binding to libsodium that provides a function named sealedbox that requires the receiver's public key. However, they also mention that the message is encrypted with an ...
2 votes
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932 views

One way shared key encryption with NaCl - is it safe to generate a throwaway keypair for the encrypting party

So, I need users to be able to pass me information that no one else can read, so I've generated a secret key. Using NaCl I create a key pair from that secret key and I share the public key of the key ...
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How feasible is it to guess the private key of libsodium by taking into account generation time?

So suppose you are doing this locally (so no network noise), and know the exact specifics of your processor too. Is it feasible to figure out the private key (while having access to the public-key) ...
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Disparity between PyNaCl docs and libsodium docs

So if we look here, it shows that libsodium uses three 3 different algorithms for this, which sounds weird to me, cause nothing indicates that anything besides Curve25519 is used in those specific ...
5 votes
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What is the best practices for storing ed25519 private keys which is used by nodes of my application to communicate with each other?

I am developing some kind of a P2P network where the nodes communicate with each other via TCP and each message is signed by Ed25519 private key. I use libsodium for signing and signature verification....
3 votes
1 answer
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Does using crypto_stream_xor allow listeners to forge crypto_secretbox messages?

I understand that NaCl's crypto_stream and crypto_stream_xor don't do any authentication like ...
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Convert sr25519 key pair to Curve25519 key pair

I'm trying to implement public key encryption that support key pairs generated by different libraries: Curve25519 - libsodium cryptoBoxKeypair() Ed25519 - Google ...
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Implement deterministic authenticated encryption using libsodium

Note: this is my first question on stack exchange, let me know if you miss some details to answer and I will edit the question accordingly Context I'm willing to create a git encryption tool (...
1 vote
1 answer
641 views

Generate secp256k1 ECC key pair with libsodium

I'm new to crypto and I want to generate a key pair, in C, which would be the equivalent of openssl ecparam -name secp256k1 -genkey -out ec-priv.pem. I love ...
2 votes
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Is CMS for data still relevant

I have an application where I need to store small to moderate amounts of data in a symmetrically encrypted form. For various reasons, CMS with an AuthEnvelopedData seems to tick all the requirements. ...
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1 answer
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Additional Data in AEAD (Chacha20-poly1305 libsodium)

I have recently been playing with Chacha20-Poly1305 in libsodium, and all of the examples state the additional data portion of the tag is stored in plaintext when encrypted. But from what I can tell ...
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How do I convert an ed25519 scalar into x25519 for encryption?

In a system I'm working with, we're using Schnorr signatures with scalars generated with libsodium's crypto_core_ed25519_scalar_random. My goal is to use the ...
2 votes
1 answer
187 views

Using crypto_sign then crypto_box_seal for anonymous messages

If you have a message M and you want the sender (alice) to be anonymous to everyone but the recipient (bob), is it ok to do? ...
3 votes
1 answer
867 views

How to find out the block size of Xchacha20 in Libsodium?

I heard that Xchacha20 works like a block cipher so that even if it wants to encrypt one byte, it will do the work of at least one block. So technically it works similar to a block cipher in counter ...
7 votes
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libsodium x25519 and Ed25519 small order check

Studying libsodium implementation of x25519 and Ed25519 I saw that it performs an small order check comparing given inputs with a hard coded blacklist of values. Is this list exhaustive or it is a ...
1 vote
1 answer
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Authenticated encryption using libsodium's crypto_box_curve25519xsalsa20poly1305

It seems that crypto_box_easy, generates a random nonce and appends it to the cipher text in libsodium. I understand using the same nonce with the same key can be ...
1 vote
1 answer
545 views

Using a nonce as a salt for key derivation

I'm currently playing a bit with PyNaCl (python binding to libsodium) and I want to use the secretbox for symmetric encryption between two parties, which means they both must know the (in my case ...
2 votes
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Negotiating a session key, when only one public-key is exchanged via QR Code

Question I want to create a secure channel between a server and a client. It is only important that the client can verify the identity of the server, not the other way around. In my special case, an ...
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Key exchange and authentication using libhydrogen

I have been able to exchange session keys on two devices using Libhydrogen's Key exchange using the N variant method. I also want to authenticate both devices to have some protection against the Man ...
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Any gotchas when deriving a symmetric key from two seeds?

Consider a connection protocol where, after jumping through several other hoops, Alice and Bob know each others' public keys; and they now want to do a RSA-handshake-kind-of-thing to come up with a ...
4 votes
1 answer
755 views

Can libsodium's X25519 encryption construction be generalized?

It is my understanding that libsodium's sealed_box is based on X25519, a Diffie-Hellman function: By combining the X25519 key agreement with a symmetric cipher and having a recipient derive the ...
12 votes
3 answers
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What happened to Poly1305AES? Is it obsolete?

I've been told that Poly1305AES is a great choice of MAC for constrained (embedded) environments. I'd checked out DJB's writing on it briefly, and have to say that I found its simplicity likeable, ...
5 votes
1 answer
3k views

Should I use NaCl or libsodium for my application?

While looking for end-to-end encryption for my app users, I stumbled upon NaCl and libsodium. I am unsure from a security perspective which of these implementations I should use for my cross-platform ...
3 votes
1 answer
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What does "crypto_box" actually mean in libsodium and NaCl?

I cannot find what "crypto_box" actually means. In general, and in specific cases, what does "box" do? I know that libsodium is authenticated encryption, but GPG is not. "Box" makes me think the ...
1 vote
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373 views

NACL with public key encryption and authentication

As suggested in this answer i can use nacl for public key encryption with: ...
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Proof possession of private key in libsodium

I would like to proof that I am in possession of private key sk for public key pk using ...
1 vote
0 answers
113 views

is forward secrecy irrelevant for non-streaming applications?

I asked a question yesterday about the Keybase key model and got no answers, unfortunately. Let me rephrase the question to make it clearer: in the case, if 2 users just want to send each other low-...
3 votes
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121 views

Verifying the ownership of curve25519 public keys

Let's say we have a group of users, authenticated by a server that providers the service, communicating on a secure channel (e.g. over HTTPS/TLS) and each user has a corresponding curve25519 key pair. ...
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1 answer
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libsodium stream encryption [closed]

I am new to cryptography, I have used OpenSSL and its aes-256-cfb cipher before to do stream encryption, which works great. Now I am going to try ...
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Would XOR'ing two Argon2 keys add extra security?

When a user registers on the app, they need to provide a password they create and we provide them with a randomly generated passphrase (e.g. Apple Cat Ladder Fire). We then use Libsodium's ...
1 vote
1 answer
222 views

Is it OK to just hash a symmetric key to derive an authentication key?

I'm using xsalsa20poly1305 for encryption in my program from libsodium. The recommended size for chunks is 4 kB. In that case, poly1305 will have authentication only for the the individual 4k chunks. ...
1 vote
1 answer
630 views

Key clamping in curve25519 not evident in generated key's binary representation

I understand with curve25519 that the private key for secret.box is clamped... I understand that this clamping process to clear ...
3 votes
1 answer
400 views

Schnorr NIZK over Ed25519

I am trying to implement the following Schnorr non-interactive zero-knowledge protocol: https://www.rfc-editor.org/rfc/rfc8235#page-7 I'm using the libsodium 1.0.16 and GNU MP libraries. I just can't ...
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1 answer
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Using ECDH for encryption and decryption [duplicate]

I'm playing with cryptography and its use with typescript on one side and PHP on the other side. Now I'm looking for routines that can encrypt and decrypt with ecdh's private and shared keys. Any ...
2 votes
1 answer
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Is it possible to derive the recipient's public key from libsodium's crypto_box?

Libsodium has "crypto_box_seal" which according to the documentation is used to "anonymously send messages to a recipient given its public key.", which hides the sender. But Is it possible for Eve to ...
4 votes
1 answer
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Which version of ChaCha is more secure?

Which version of ChaCha is more secure? XChaCha20-Poly1305-IETF ChaCha20-IETF-Poly1305 ChaCha20-Poly1305 I am looking for 256bit strength for large datasets. ...
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specific scenario question relating to using NACL crypto_box in a protocol

Scenario 1: SenderA sends message1 to ReceiverB message1 is encrypted using NACL crypto_box using SenderA secret key and ReceiverB public key. we understand that the NACL crypto_box authenticator ...
3 votes
2 answers
2k views

Using public-key signature instead of having API key

I am designing an application that will need an API key. At first I believed that generating a long, random token would be secure enough (say 32 chars string that includes 0-9, a-z and A-Z), and then ...
3 votes
1 answer
473 views

Representations of secret keys on Curve25519

https://datatracker.ietf.org/doc/html/draft-josefsson-tls-curve25519-06#appendix-A.2 gives the following as a secret key / public key combo: ...
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How can I follow the validation and verification recommendations of the NaCl (sodium) secretbox library?

I was advised to use crypto_secretbox_xsalsa20poly1305 due to its simplicity and because it's safe against timing attacks. I'm reading the secretbox tutorial, and ...