Details
Ristretto (PHP)

Implements a type-safe API for working with the Ristretto Group
in PHP projects.
Requirements
Installing
composer require paragonie/ristretto
Documentation
There are two basic types: ScalarValue
and GroupElement
.
The ScalarValue
object wraps a big integer between 0 and the order of the Ristretto Group, L
.
The GroupElement
object wraps a group element of the Ristretto Group.
If an analogy helps, in the world of Ed25519 and X25519, the ScalarValue
is your secret key,
and GroupElement
is your public key.
For that reason, there are also a SecretKey
and PublicKey
class, which contains some
basic helper methods for ease-of-use.
Usage
You can convert from scalars to group elements with multBase()
, and then use
scalarPointMultiply()
to perform a commutative group action (e.g. Diffie-Hellman).
<?php
use ParagonIE\Ristretto\{GroupElement, ScalarValue};
$aliceSecret = ScalarValue::random();
$alicePublic = $aliceSecret->multBase();
$bobSecret = ScalarValue::random();
$bobPublic = $bobSecret->multBase();
// You can perform a similar commutative group action
$aliceToBob = $aliceSecret->scalarPointMultiply($bobPublic);
$bobToAlice = $bobSecret->scalarPointMultiply($alicePublic);
var_dump($aliceToBob->equals($bobToAlice)); // bool(true)
Otherwise, most operations are within a given type (GroupElement to GroupElement,
ScalarValue to ScalarValue).
GroupElement
<?php
use ParagonIE\Ristretto\{GroupElement};
$x = GroupElement::random();
$y = GroupElement::random();
$z = $x->add($y);
$w = $z->sub($y);
var_dump($w->equals($x)); // bool(true)
ScalarValue
Example
This is a PHP implementation of the libsodium example protocol.
> Perform a secure two-party computation of f(x) = p(x)^k
. x
is the input sent to the second party
> by the first party after blinding it using a random invertible scalar r
, and k
is a secret key
> only known by the second party. p(x)
is a hash-to-group function.
<?php
use ParagonIE\Ristretto\{GroupElement};
// -------- First party -------- Send blinded p(x)
$x = random_bytes(64);
// Compute px = p(x), a group element derived from x
$px = GroupElement::fromHash($x);
// Compute a = p(x) * g^r
$r = ScalarValue::random();
$gr = $r->multBase();
$a = $px->add($gr);
// -------- Second party -------- Send g^k and a^k
$k = ScalarValue::random();
// Compute v = g^k
$v = $k->multBase();
// Compute b = a^k
$b = $k->scalarPointMultiply($a);
// -------- First party -------- Unblind f(x)
// Compute vir = v^(-r)
$ir = $r->negate();
$vir = $v->scalarPointMultiply($ir);
// Compute f(x) = b v^(-r) = (p(x) g^r)^k * (g^k)^(-r)
// = (p(x) g)^k g^(-k) = p(x)^k
$fx = $b->add($vir);
// --------- Correctness testing -----------
// If you knew both p(x) and k, you could calculate it directly.
// Directly calculate p(x)^k with both parties' secrets
$pxk = $px->scalarPointMultiply($k);
var_dump($fx->equals($pxk)); // bool(true)
|
Name: |
How to Implement PHP Type Safety Using Ristretto PHP |
Base name: |
ristretto-php |
Description: |
Manipulate values in type safe way using classes |
Version: |
1.0.0 |
PHP version: |
5 |
License: |
MIT/X Consortium License |
All time users: |
33 users |
All time rank: |
10757 |
Week users: |
0 users |
Week rank: |
200  |
|
|
 November 2022
Number 6 |
Type safety is a characteristic of languages that require certain operations with values of the correct values. This characteristic is good for catching bugs early in application development.
PHP was not originally a type-safe language. PHP is more tolerant of developer mistakes. This fact makes PHP a more accepted language among developers without formal education in programming.
This package provides a solution to make PHP more type-safe to avoid that applications shipping code with programming mistakes.
It provides several classes that implement type-safe operations, including some that are useful for cryptography applications.
With this package, you can implement cryptography applications with greater quality when compared to applications that do not use type safety.
Manuel Lemos |
Not yet rated by the users |
|
Applications that use this package |
|
No pages of applications that use this class were specified.
If you know an application of this package, send a message to the author to add a link here.
|
Files |
|
File |
Role |
Description |
ci.yml |
Data |
Auxiliary data |
psalm.yml |
Data |
Auxiliary data |
|
Files |
|
File |
Role |
Description |
ci.yml |
Data |
Auxiliary data |
psalm.yml |
Data |
Auxiliary data |