diffie_hellman 1.1.4

Dart implementation of finite field Diffie-Hellman. Based on PKCS#3.

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 (160-bit Prime Order Subgroup)	224	112
24	2048-bit (160-bit Prime Order Subgroup)	256	112

References

• https://www.teletrust.de/fileadmin/files/oid/oid_pkcs-3v1-4.pdf
• https://www.ietf.org/rfc/rfc3526.txt
• https://datatracker.ietf.org/doc/html/rfc2409
• https://datatracker.ietf.org/doc/html/rfc5114