A Dart library implementing cryptographic algorithms and primitives, modeled on the BouncyCastle library.
Pointy Castle #
Please note that this is an unofficial release of pointycastle for the steel_crypt library with the newest features. The official release will come out at https://pub.dev/packages/pointycastle.
A Dart library for encryption and decryption. In this release, most of the classes are ports of Bouncy Castle from Java to Dart. The porting is almost always direct except for some classes that had been added to ease the use of low level data.
To make sure nothing fails, tests and benchmarks for every algorithm are provided. The expected results are taken from the Bouncy Castle Java version and also from standards, and matched against the results got from Pointy Castle.
This library was adopted from the original project at https://github.com/PointyCastle/pointycastle at the request of the authors to help support ongoing development. A list of major contributors is provided at contributors.md
In this release, the following algorithms are implemented.
(Most of the below can be used directly with the registry, which is an easy way to instantiate classes in PointyCastle. See "Using the Registry" for more).
(The relevant parameter type is provided for all the algorithms. To initialize an algorithm, call
AEAD ciphers: To use with the registry, instantiate like this
AEADCipher('ChaCha20-Poly1305'). Ciphers use
AEADParameters to initialize.
Block ciphers: To use with the registry, instantiate like this
PaddedBlockCipher('AES/SomeBlockModeHere/SomePaddingHere') or like this
- Note that block ciphers can be used in stream cipher modes of operation
Block modes of operation: Most modes use
ParametersWithIV to initialize. ECB uses
KeyParameter and GCM uses
- 'CBC' (Cipher Block Chaining mode)
- 'ECB' (Electronic Code Book mode)
- 'CFB-64' (Cipher Feedback mode, using blocks)
- 'GCTR' (GOST 28147 OFB counter mode, using blocks)
- 'OFB-64' (Output FeedBack mode, using blocks)
- 'CTR'/'SIC' (Counter mode, using blocks)
- Authenticated block modes of operation
- 'GCM' (Galois-Counter mode)
Stream modes of operation: All modes use
ParametersWithIV to initialize.
- 'CTR'/'SIC' (Counter mode, as a traditional stream)
Asymmetric block ciphers: Instantiate using the registry like this
AsymmetricBlockCipher('RSA/SomeEncodingHere'). Initialization requires a
Asymmetric block cipher encodings:
Stream ciphers: Instantiation using registry is like this
StreamCipher('ChaCha20/20'). Initialization requires a
- 'ChaCha20/(# of rounds)' (original implementation)
- 'ChaCha7539/(# of rounds)' (RFC-7539 implementation)
- If you don't know how many ChaCha rounds to use, use 20.
Digests: Instantiate using registry like this
Digest('Keccak/384'). No initialization is necessary.
- 'SHA-512/t' (t=8 to 376 and 392 to 504 in multiples of 8)
MACs: Instantiate using registry like this
Mac(SomeBlockCipher/Poly1305). CMAC and HMAC require a
KeyParameter and Poly1305 requires a
Signatures: Instantiate using registry like this
Password based key derivators: Instantiation using registry like this
KeyDerivator('scrypt'). To initialize, you'll need a
HMAC based key derivators: Instantiate using registry like this
KeyDerivator('SomeDigestHere/HKDF'). To initialize, use an
Asymmetric key generators Instantiate using registry like this
KeyDerivator('RSA'). To initialize, use
- Based on block cipher in CTR mode
- Based on block cipher in CTR mode with auto reseed (for forward security)
- Based on Fortuna algorithm
Instantiating implementation objects #
There are two ways to instantiate objects that implement the algorithms:
- using the registry, or
- without the registry.
Using the registry
Using the registry, the algorithm name is provided to high-level class factories.
This is especially convenient when an algorithm involves multiple algorithm implementation classes to implement. All the necessary classes can all be instantiated with a single name (e.g. "SHA-256/HMAC" or "SHA-1/HMAC/PBKDF2" or "AES/CBC/PKCS7"), and they are automatically combined together with the correct values.
final sha256 = Digest("SHA-256"); final sha1 = Digest("SHA-1"); final md5 = Digest("MD5"); final hmacSha256 = Mac("SHA-256/HMAC"); final hmacSha1 = Mac("SHA-1/HMAC"); final hmacMd5 = Mac("MD5/HMAC"); final derivator = KeyDerivator("SHA-1/HMAC/PBKDF2"); final signer = Signer("SHA-256/RSA");
Without the registry
Without the registry, each implementation class must be instantiated using its constructor.
If an algorithm involves multiple algorithm implementation classes, they each have to be individually instantiated and combined together with the correct values.
final sha256 = SHA256Digest(); final sha1 = SHA1Digest(); final md5 = MD5Digest(); final hmacSha256 = HMac(SHA256Digest(), 64); final hmacSha512 = HMac(SHA512Digest(), 128); final hmacMd5 = HMac(MD5Digest(), 64); final derivator = PBKDF2KeyDerivator(HMac(SHA256Digest(), 64)); final signer = RSASigner(SHA256Digest(), '0609608648016503040201');
Registry vs without registry
Using the registry means that all algorithms will be imported by default, which can increase the compiled size of your program.
To avoid this, instantiate all classes directly by using the constructors. But which classes can be instantiated with its constructor will depend on which libraries have been imported.
Importing libraries #
A program can take one of these three approaches for importing Point Castle libraries:
- only import pointycastle.dart;
- only import exports.dart; or
- import api.dart and individual libraries as needed.
Only import pointycastle.dart
The "pointycastle.dart" file exports:
- the high-level API; and
- implementations of the interfaces.
But it does not export any of the algorithm implementation classes.
With this import, none of the implementation classes can be instantiated directly. The program can only use the registry.
final sha256 = Digest("SHA-256"); // final md5 = MD5Digest(); // not available final p = Padding("PKCS7"); // final s = FortunaRandom(); // not available
Only import exports.dart
The "export.dart" file exports:
- the high-level API,
- implementations of the interfaces; and
- every algorithm implementation class.
That is, everything!
With this import, all of the implementation classes can be instantiated directly. The program can also use the registry.
For example, this works without any additional imports:
final sha256 = Digest("SHA-256"); final md5 = MD5Digest(); final p = Padding("PKCS7"); final s = FortunaRandom();
Import api.dart and individual libraries
The "api.dart" exports only:
- the high-level API.
It does not include the implementations of the interfaces, nor any algorithm implementation class.
import "package:pointycastle/api.dart"; // additional imports will be needed
With this import, only some of the implementation classes can be instantiated directly (i.e. those that are also explicitly imported). The program can also use the registry.
For example, the following only works because of the additional imports:
// In addition to "package:pointycastle/api.dart": import "package:pointycastle/digests/sha256.dart"; import "package:pointycastle/digests/md5.dart" import 'package:pointycastle/paddings/pkcs7.dart'; final sha256 = Digest("SHA-256"); final md5 = MD5Digest(); final p = Padding("PKCS7"); // final s = FortunaRandom(); // not available without 'package:pointycastle/random/fortuna_random.dart'
Some articles on how to use some of Pointy Castle's features can be found under the tutorials directory in the sources.
- Calculating a digest - calculating a hash or digest (e.g. SHA-256, SHA-1, MD5)
- Calculating a HMAC - calculating a hash-based message authentication code (e.g. HMAC-SHA256, HMAC-SHA1)
- Using AES-CBC - block encryption and decryption with AES-CBC
- Using RSA - key generation, signing/verifying, and encryption/decryption
- Some tips on using Pointy Castle
Note: the above links are to the most recent versions on the master branch on GitHub. They may be different from the version on pub.dev.