category

x25519

X25519 Diffie-Hellman key agreement implementation (RFC 7748). Requires exact, unbounded integer arithmetic for arithmetic modulo the 255-bit field prime.

Availability:
logtalk_load(crypto(loader))
Author: Paulo Moura
Version: 1:0:0
Date: 2026-08-03
Compilation flags:
static
Complements:
crypto
Uses:
list
type
Remarks:
(none)
Inherited public predicates:
(none)

Public predicates

x25519_keypair/2

Generates a fresh random 32-byte PrivateKey and derives the corresponding 32-byte PublicKey. Available only on backends with unbounded integer arithmetic.

Compilation flags:
static
Template:
x25519_keypair(PrivateKey,PublicKey)
Mode and number of proofs:
x25519_keypair(-list(byte),-list(byte)) - one

x25519_public_key/2

Derives the 32-byte X25519 PublicKey corresponding to a 32-byte PrivateKey. Available only on backends with unbounded integer arithmetic.

Compilation flags:
static
Template:
x25519_public_key(PrivateKey,PublicKey)
Mode and number of proofs:
x25519_public_key(+list(byte),-list(byte)) - one_or_error
Exceptions:
PrivateKey is a partial list or a list with an element which is a variable:
instantiation_error
PrivateKey is neither a variable nor a list of 32 bytes:
type_error(list(byte,32),PrivateKey)
PrivateKey contains a non-integer byte:
type_error(integer,Byte)
PrivateKey contains an integer outside the byte range:
domain_error(byte,Byte)

x25519_shared_secret/3

Computes the 32-byte X25519 SharedSecret using PrivateKey and PeerPublicKey. Fails when the result is all zeroes. Available only on backends with unbounded integer arithmetic.

Compilation flags:
static
Template:
x25519_shared_secret(PrivateKey,PeerPublicKey,SharedSecret)
Mode and number of proofs:
x25519_shared_secret(+list(byte),+list(byte),-list(byte)) - zero_or_one_or_error
Exceptions:
PrivateKey is a partial list or a list with an element which is a variable:
instantiation_error
PrivateKey is neither a variable nor a list of 32 bytes:
type_error(list(byte,32),PrivateKey)
PrivateKey contains a non-integer byte:
type_error(integer,Byte)
PrivateKey contains an integer outside the byte range:
domain_error(byte,Byte)
PeerPublicKey is a partial list or a list with an element which is a variable:
instantiation_error
PeerPublicKey is neither a variable nor a list of 32 bytes:
type_error(list(byte,32),PeerPublicKey)
PeerPublicKey contains a non-integer byte:
type_error(integer,Byte)
PeerPublicKey contains an integer outside the byte range:
domain_error(byte,Byte)

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)