Dart Diffie-Hellman
Dart implementation of finite field Diffie-Hellman. Based on PKCS#3.
Usage
DhPkcs3Engine dhEngine = DhPkcs3Engine.fromGroup(DhGroup.g5);
DhPkcs3Engine otherDhEngine = DhPkcs3Engine.fromGroup(DhGroup.g5);
DhKeyPair keyPair = dhEngine.generateKeyPair();
DhKeyPair otherKeyPair = otherDhEngine.generateKeyPair();
print('Public Key: ${keyPair.publicKey.value}');
print('Private Key: ${keyPair.privateKey.value}');
print('Other public Key: ${otherKeyPair.publicKey.value}');
print('Other private Key: ${otherKeyPair.privateKey.value}');
print(
'Secret Key: ${dhEngine.computeSecretKey(otherKeyPair.publicKey.value)}',
);
print(
'Other secret Key: ${otherDhEngine.computeSecretKey(keyPair.publicKey.value)}',
);
Engine configuration
The engine can be configured in three ways:
Predefined group
This factory constructor allows you to specify a Diffie-Hellman group to use. Each group has a predefined parameter definition
DhPkcs3Engine dhEngine = DhPkcs3Engine.fromGroup(DhGroup.g18);
Custom parameter
It's also possible to define a custom parameter definition (e.g. using the same from a group but with different values)
DhPkcs3Engine dhEngine = DhPkcs3Engine.fromParameter(DhGroup.g18.parameter.copyWith(l: 1024));
Existing key pair
The engine can be created from an existing key pair
DhPrivateKey privateKey = DhPrivateKey.fromPem('...');
DhPublicKey publicKey = DhPublicKey.fromPem('...');
DhKeyPair keyPair = DhKeyPair(privateKey: privateKey, publicKey: publicKey);
DhPkcs3Engine dhEngine = DhPkcs3Engine.fromKeyPair(keyPair);
PEM serialization/deserialization
Each key can be constructed from a PEM string
DhPrivateKey privateKey = DhPrivateKey.fromPem('...');
DhPublicKey publicKey = DhPublicKey.fromPem('...');
On the other hand, the keys can be serialized to a PEM string
String privateKeyPem = privateKey.toPem();
String publicKeyPem = publicKey.toPem();
The same applies to the DH parameters
DhParameter parameter = DhParameter.fromPem('...');
String parameterPem = parameter.toPem();
DH Groups
| Group ID | Modulus length (p) | Exponent size (l) (in bits) | Strength (in bits) |
|---|---|---|---|
| 1 | 768-bit | 160 | - |
| 2 | 1024-bit | 160 | 80 |
| 5 | 1536-bit | 240 | 120 |
| 14 | 2048-bit | 320 | 160 |
| 15 | 3072-bit | 384 | 190 |
| 16 | 4096-bit | 480 | 240 |
| 17 | 6144-bit | 512 | 250 |
| 18 | 8192-bit | 640 | 320 |
| 22 | 1024-bit (160-bit Prime Order Subgroup) | 160 | 80 |
| 23 | 2048-bit (224-bit Prime Order Subgroup) | 224 | 112 |
| 24 | 2048-bit (256-bit Prime Order Subgroup) | 256 | 112 |