leigh / curve25519
Pure PHP implementation of the Curve25519 Diffie-Hellman function
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Requires
- php: >=5.4
Requires (Dev)
- phpunit/phpunit: ~4.0
This package is not auto-updated.
Last update: 2024-10-26 19:05:20 UTC
README
This is a pure PHP implementation of the Curve25519 Diffie-Hellman function.
The library has been written to be high performance (relative to PHP), not pretty. It obviously doesn't perform anywhere close to a native implementation.
Usage:
$mySecret = random_bytes(32);
$myPublic = \Curve25519\publicKey($mySecret);
$shared = \Curve25519\sharedKey($mySecret, $theirPublic);
Multi-party shared secrets:
When more than two parties are communicating, it is necessary to communicate intermediate values so that each party can compute a common shared secret
$alicePrivate = str_repeat('a', 32);
$bobPrivate = str_repeat('b', 32);
$carolPrivate = str_repeat('c', 32);
$alicePublic = \Curve25519\publicKey($alicePrivate); // Send to Bob
$bobPublic = \Curve25519\publicKey($bobPrivate); // Send to Carol
$carolPublic = \Curve25519\publicKey($carolPrivate); // Send to Alice
$aliceCarolShared = \Curve25519\sharedKey($alicePrivate, $carolPublic); // Send to Bob
$bobAliceShared = \Curve25519\sharedKey($bobPrivate, $alicePublic); // Send to Carol
$carolBobShared = \Curve25519\sharedKey($carolPrivate, $bobPublic); // Send to Alice
$aliceShared = \Curve25519\sharedKey($alicePrivate, $carolBobShared);
$bobShared = \Curve25519\sharedKey($bobPrivate, $aliceCarolShared);
$carolShared = \Curve25519\sharedKey($carolPrivate, $bobAliceShared);
// An adversary potentially observed f(a), f(b), f(c), f(ab), f(ac), and f(bc),
// whereas each party solved for f(abc)
var_dump($aliceShared === $bobShared && $bobShared === $carolShared);