/ 
Crypt-Sodium-XS-0.000021
/ Crypt::Sodium::XS::scalarmult
Security Advisories (3)
CVE-2025-15444 (2026-01-06)

Crypt::Sodium::XS module versions prior to 0.000042, for Perl, include a vulnerable version of libsodium libsodium <= 1.0.20 or a version of libsodium released before December 30, 2025 contains a vulnerability documented as CVE-2025-69277  https://www.cve.org/CVERecord?id=CVE-2025-69277 . The libsodium vulnerability states: In atypical use cases involving certain custom cryptography or untrusted data to crypto_core_ed25519_is_valid_point, mishandles checks for whether an elliptic curve point is valid because it sometimes allows points that aren't in the main cryptographic group. 0.000042 includes a version of libsodium updated to 1.0.20-stable, released January 3, 2026, which includes a fix for the vulnerability.

CVE-2026-30910 (2026-03-08)

Crypt::Sodium::XS versions through 0.001000 for Perl has potential integer overflows. Combined aead encryption, combined signature creation, and bin2hex functions do not check that output size will be less than SIZE_MAX, which could lead to integer wraparound causing an undersized output buffer. This can cause a crash in bin2hex and encryption algorithms other than aes256gcm. For aes256gcm encryption and signatures, an undersized buffer could lead to buffer overflow. Encountering this issue is unlikely as the message length would need to be very large. For bin2hex the input size would have to be > SIZE_MAX / 2 For aegis encryption the input size would need to be > SIZE_MAX - 32U For other encryption the input size would need to be > SIZE_MAX - 16U For signatures the input size would need to be > SIZE_MAX - 64U

CVE-2025-69277 (2025-12-31)

libsodium before ad3004e, in atypical use cases involving certain custom cryptography or untrusted data to crypto_core_ed25519_is_valid_point, mishandles checks for whether an elliptic curve point is valid because it sometimes allows points that aren't in the main cryptographic group.

NAME

Crypt::Sodium::XS::scalarmult - Point-scalar multiplication over the edwards25519 curve

SYNOPSIS

use Crypt::Sodium::XS::scalarmult ':default';
use Crypt::Sodium::XS 'sodium_random_bytes';

my $keysize = Crypt::Sodium::XS->box->SECRETKEYBYTES;
my $client_sk = sodium_random_bytes($keysize);
my $client_pk = scalarmult_base($client_sk);
my $server_sk = sodium_random_bytes($keysize);
my $server_pk = scalarmult_base($client_sk);

# do not use output directly for key exchange use Crypt::Sodium::XS::kx.
# or, if you insist:

use Crypt::Sodium::XS::generichash 'generichash_init';

# client side:
my $q = scalarmult($client_sk, $server_pk);
my $hasher = generichash_init();
$hasher->update($q, $client_pk, $server_pk);
my $client_shared_secret = $hasher->final;

# server side:
my $q = scalarmult($server_sk, $client_pk);
my $hasher = generichash_init();
$hasher->update($q, $client_pk, $server_pk);
my $server_shared_secret = $hasher->final;

# $client_shared_secret and $server_shared_secret are now identical keys.

DESCRIPTION

Crypt::Sodium::XS::scalarmult provides an API to multiply a point on the edwards25519 curve.

This can be used as a building block to construct key exchange mechanisms, or more generally to compute a public key from a secret key. For key exchange, you generally want to use Crypt::Sodium::XS::kx instead.

FUNCTIONS

Nothing is exported by default. A :default tag imports the functions and constants as documented below.

scalarmult_keygen

my $secret_key = scalarmult_keygen();

scalarmult_base

my $public_key = scalarmult_base($secret_key);

scalarmult

my $q = scalarmult($my_secret_key, $their_public_key);

CONTSANTS

scalarmult_BYTES

my $public_key_length = scalarmult_BYTES();

scalarmult_SCALARBYTES

my $shared_and_secret_key_length = scalarmult_SCALARBYTES();

PRIMITIVES

There are no primitive-specific functions for this module. It always uses X25519 (ECDH over Curve25519). See RFC 7748.

SEE ALSO

Crypt::Sodium::XS
Crypt::Sodium::XS::OO::scalarmult
https://doc.libsodium.org/advanced/scalar_multiplication

FEEDBACK

For reporting bugs, giving feedback, submitting patches, etc. please use the following:

  • IRC channel #sodium on irc.perl.org.

  • Email the author directly.

For any security sensitive reports, please email the author directly or contact privately via IRC.

AUTHOR

Brad Barden <perlmodules@5c30.org>

COPYRIGHT & LICENSE

Copyright (c) 2022 Brad Barden. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.