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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What is special about an entropy count (RNDGETENTCNT) of 160 for libsodium initialization?

(Moved from StackOverflow) In the Usage documentation for libsodium, before calling the initialization function sodium_init, they suggest you check the entropy ...
Zane Beckwith's user avatar
6 votes
2 answers
3k views

What is the difference between a sealed box and a normal box in libsodium?

I'm trying to learn libsodium to better my crypto knowledge. One nagging question I have is what is the difference between libsodium's sealed box and their normal box? Not in terms of technicalities ...
Sukima's user avatar
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I have this list of LibSodium primitives, which should I pick so that the implementations tend to be interoperable?

When I integrate lib sodium, into a c# project, and try to consume, encryption and decryption in a particular way, it works, but the confusion is about, which method to use while encryption or ...
Kaushal B's user avatar
2 votes
0 answers
151 views

P2P Website/Database Encryption Process

Sorry if this doesn't fit the guidelines, but I believe it is a conceptual issue that is not opinion-based and can be reasonably answered in a single authoritative answer (I'm also struggling to find ...
thebronsonite's user avatar
2 votes
2 answers
623 views

Why are 48 bytes appended to Libsodium encrypted messages if nonce is 24 bits?

When encrypting a string through the Libsodium secret box feature, the ciphertext is 48 bytes longer than the plain text message ... I am wondering why this is ... since the nonce is only 24 bytes.
abc's user avatar
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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 ...
stojanman's user avatar
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7 votes
2 answers
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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 ...
user3368561's user avatar
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Encrypt or decrypt using the private key, and decrypt using the public key?

I am currently trying to figure out if my following scheme is implementable in ECC or whether I can use existing implementation. At first I was going with libsodium but it seems that it really doesn't ...
MrBorrowck's user avatar
1 vote
1 answer
332 views

Is libsodium's `box` construct secure without additional manual padding of the plaintext before encryption?

I have read the following questions and answers: How safe are Libsodium Crypto Boxes? What can be learned from the ciphertext of LibSodium's crypto_box_detached()? However, neither of these ...
notacryptographer's user avatar
5 votes
1 answer
4k views

How to use Libsodium encryption (in PHP) in the most secure possible way?

In a PHP project in which fool-proof encryption is fundamental, I'm using the Libsodium library. Hope you guys can shine some light on the following questions. For all of the following functions, it ...
abc's user avatar
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How safe are Libsodium Crypto Boxes?

I am currently working on a huge PHP project and we are seriously considering to use the Libsodium PHP library in it. My question is related to the "sodium crypto box" functionality. We would use ...
abc's user avatar
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Libsodium installation issue: Invalid library (maybe not a PHP library) 'sodium.so' in Unknown on line 0 .... [closed]

I've been struggling since days to install libsodium on my Debian9/php7.0(with fpm) server ... When I follow the steps outlined on https://paragonie.com/book/pecl-libsodium/read/00-intro.md#installing-...
abc's user avatar
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Does it matter whether the KDF salt is integrity protected?

I am writing a simple application, mainly as a fun challenge, but also to hopefully someday use as my password manager. I'm using pynacl's SecretBox, which ...
user371366's user avatar
2 votes
1 answer
640 views

Is the following crypto compatible so that I can use the same keys for both products (Wireguard & Libsodium)?

I am wondering if it is possible to use the public/private keys of two WireGuard peers also in another communication channel using libsodium? According to the WireGuard Protocol documentation and the ...
user3637203's user avatar
1 vote
1 answer
2k views

How to find the secret key and nonce from two messages encrypted using the same nonce?

As far as I understand, nonces must not be reused because their reuse allows public key encryption to be broken. If I use NaCl's crypto_box http://nacl.cr.yp.to/...
fadedbee's user avatar
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1 answer
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Why NaCL does not provide anonymous public key cryptography?

At the same time Sodium provides API for anonymous encryption without using ephemeral keys. Is it a bad practice to just use other user public key to encrypt a message?
Andrey Kuznetsov's user avatar
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1 answer
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How do I properly calculate an inverse element for curve25519 when implementing Sphinx password store protocol?

There's a new password store mechanism, called Sphinx http://webee.technion.ac.il/~hugo/sphinx.pdf which is very nice and protects from device or user compromise. I haven't found any implementations ...
John dow's user avatar
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1 answer
751 views

Nonce reuse resistance

I read this article and I think the approach outlined there is very interesting for one of our use case. We use ChaCha20 Poly1305 (via Sodium ...
Ayende Rahien's user avatar
3 votes
1 answer
338 views

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 ...
Jack O'Connor's user avatar
4 votes
2 answers
761 views

Why/how is libsodium/nacl's cryptobox repudiable?

https://nacl.cr.yp.to/box.html see "security model". As far as I can see, Alice encrypts a message using her private key, Bob's public key and a nonce. Bob decrypts the message using Alice's public ...
fadedbee's user avatar
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Why do two Argon hashes with the same password differ?

Can someone explain to me what the ArgonHashString function in libsodium returns (i'm using the .net port). For example i called it twice with the same string: ...
coding4fun's user avatar
5 votes
1 answer
2k views

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....
defuz's user avatar
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19 votes
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Argon2 output length and parameter storage?

I just started using the libsodium port for .net today and the output length parameter kind of confused me (I'm using the argon2i implementation). With my limited exposure to hashing, whatever hash ...
coding4fun's user avatar
3 votes
1 answer
2k views

Can I always derive a key pair from password+salt with libsodium?

I'm using libsodium to create public/secret key pairs from a password and salt combination by using crypto_pwhash_scryptsalsa208sha256 to generate a seed and ...
Mauricio de Souza's user avatar
0 votes
1 answer
889 views

Sodium crypto_aead_aes256gcm_encrypt ciphertext length > plaintext length

Using the crypto_aead_aes256gcm functions from Sodium produces a ciphertext of "at most mlen (plaintext length) + crypto_aead_aes256gcm_ABYTES bytes (16 bytes) are put into c (ciphertext), and the ...
user10984587's user avatar
1 vote
2 answers
296 views

Are there any disadvantages of using libsodiums helpers for en-/decoding/comparision instead of the native ones?

Libsodium has some helpers, which allow hexdecimal decoding, encoding and also constant-time string comparison. So if you use the php binding libsodium-php you ...
rugk's user avatar
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1 vote
1 answer
500 views

Why does NaCl's crypto_auth have twice the security level of crypto_onetimeauth?

The crypto_auth function produces a 256-bit HMAC, with a 512-bit version also available. But the crypto_onetimeauth function (...
Jack O'Connor's user avatar
1 vote
1 answer
445 views

Is PKCS#7 padding generated with a pseudo-random-number generator okay?

Let's take this PHP code. We use libsodium and libsodium-php. You have $text, $senderPrivateKey, ...
rugk's user avatar
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1 vote
0 answers
102 views

What is the shortest fingerprint of a Curve25519 public key that is secure [duplicate]

My clients have to exchange public keys. To ensure security they are exchanging fingerprints and typing them into the computer by hands. I want the fingerprints to be as short as possible. I am ...
Nathan's user avatar
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4 votes
1 answer
2k views

How does constant-time comparison work?

libsodium has a method for comparing two byte sequences in constant time. Is the idea here to simply avoid early-out if a difference in the data is detected? When I first heard of such a thing I ...
user avatar
4 votes
2 answers
1k views

Curve25519 - Alice can decrypt her own message to Bob?

I'm developing an application with multiple clients and one server. All clients will have the same hard-coded Curve25519 key pair as well as the server's public key. The server will have its own key ...
TimH - Codidact's user avatar
3 votes
2 answers
842 views

Using related pair of cryptographic keys to open/seal plaintext

I am using curve25519xsalsa20poly1305/fn.seal from sodiumoxide crate written in Rust language which is a wrapper over libsodium ...
ustulation's user avatar
4 votes
1 answer
545 views

How do I tack on "additional data" to libsodium's public-key authenticated encryption?

I note that libsodium provides AEAD when using symmetric cryptography. And yet, under section 8 (Public-key cryptography) there are no public-key methods described which allow for additional data (AD)...
user3325588's user avatar
64 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 ...
Simon's user avatar
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3 votes
2 answers
2k views

Point addition in NaCl/libsodium (Curve25519)

In NaCl and libsodium, the crypto_scalarmult function implements the operation $Q = kP$ (scalar/point multiplication). There doesn't seem to be a function for point ...
user avatar
2 votes
1 answer
5k views

Why is the public/private key length used in libsodium so much shorter than needed for RSA [duplicate]

Reading the libsodium source I see that is uses a key length of 32 bytes (256 bit) for private/public key encryption. For RSA private/public key encryption a key length of 2048 (or 4095) bit is ...
Nathan's user avatar
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2 votes
1 answer
2k views

Encryting data with password for local storage using libsodium

I want to encrypt data that is stored on the hard disk using a user-entered password. For this I look into the sodium docs and all I can find for symmetric encryption is authenticated encryption. ...
Nathan's user avatar
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5 votes
1 answer
1k views

Security implications of public nonce

I'm planning to use the crypto_box() functions of Nacl (or, alternatively, the crypto_box_easy() functions of libsodium) to ...
dsd's user avatar
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3 votes
1 answer
566 views

Standard serialization format for libsodium-based messages

Does anyone know of a standardized serialization format which can be (or already is) widely used for encrypted messages? For a variety of reasons (mostly complexity, age and poor support across a lot ...
rmalayter's user avatar
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5 votes
1 answer
2k views

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 ...
TerrorByte's user avatar

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