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77 lines
3.4 KiB
Markdown
77 lines
3.4 KiB
Markdown
# SipHash
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[](https://travis-ci.org/zackehh/siphash-java) [](https://coveralls.io/github/zackehh/siphash-java?branch=master)
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A Java implementation of the SipHash cryptographic hash family. Supports any variation, although defaults to the widely used SipHash-2-4. Can be used with either full input, or used as a streaming digest.
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This library was heavily influenced by [veorq's C implementation](https://github.com/veorq/siphash) and [Forward C&C's reference implementation](http://www.forward.com.au/pfod/SipHashJavaLibrary/) - I just decided it was time a Java implementation of SipHash made it onto Maven :).
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## Setup
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`siphash` is available on Maven central, via Sonatype OSS:
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```
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<dependency>
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<groupId>com.zackehh</groupId>
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<artifactId>siphash</artifactId>
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<version>1.0.0</version>
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</dependency>
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```
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## Usage
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There are two ways of using SipHash (see below). Both return a `SipHashResult` which can be used to retrieve the result in various forms. All constructors can take arguments to specify the compression rounds. For further usage, please visit the [documentation](http://www.javadoc.io/doc/com.zackehh/siphash).
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#### Full Input Hash
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The first is to simple create a `SipHash` instance and use it to repeatedly hash using the same key.
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The internal state is immutable, so you can hash many inputs without having to recreate a new `SipHash` instance (unless you want a new key).
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```java
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SipHash hasher = new SipHash("0123456789ABCDEF".getBytes());
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SipHashResult result = hasher.hash("my-input".getBytes());
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System.out.println(result.get()); // 182795880124085484 <-- this can overflow
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System.out.println(result.getHex()); // "2896be26d3374ec"
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System.out.println(result.getHex(true)); // "02896be26d3374ec"
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System.out.println(result.getHex(SipHashCase.UPPER)); // "2896BE26D3374EC"
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System.out.println(result.getHex(true, SipHashCase.UPPER)); // "02896BE26D3374EC"
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```
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#### Streaming Hash
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The second is to use the library as a streaming hash, meaning you can apply chunks of bytes to the hash as they become available.
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Using this method you must create a new digest every time you want to hash a different input as the internal state is mutable.
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```java
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SipHashDigest digest = new SipHashDigest("0123456789ABCDEF".getBytes());
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digest.update("chu".getBytes());
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digest.update("nked".getBytes());
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digest.update(" string".getBytes());
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SipHashResult result = digest.finish();
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System.out.println(result.get()); // 3502906798476177428 <-- this can overflow
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System.out.println(result.getHex()); // "309cd32c8c793014"
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System.out.println(result.getHex(true)); // "309cd32c8c793014"
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System.out.println(result.getHex(SipHashCase.UPPER)); // "309CD32C8C793014"
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System.out.println(result.getHex(true, SipHashCase.UPPER)); // "309CD32C8C793014"
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```
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## Contributing
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If you wish to contribute (awesome!), please file an issue first! All PRs should pass `mvn clean verify` and maintain 100% test coverage.
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## Testing
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Tests are run using `mvn`. I aim to maintain 100% coverage where possible (both line and branch).
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Tests can be run as follows:
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```bash
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$ mvn clean verify
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``` |