https://github.com/tlrasor/incremental_hmac
Incremental HMAC API for Crystal
https://github.com/tlrasor/incremental_hmac
crystal crystal-lang crystal-language crystal-shards hmac standard-library utility-library
Last synced: 2 months ago
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Incremental HMAC API for Crystal
- Host: GitHub
- URL: https://github.com/tlrasor/incremental_hmac
- Owner: tlrasor
- License: mit
- Created: 2019-10-07T18:22:43.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2019-10-07T20:40:30.000Z (over 5 years ago)
- Last Synced: 2025-02-05T21:58:17.417Z (4 months ago)
- Topics: crystal, crystal-lang, crystal-language, crystal-shards, hmac, standard-library, utility-library
- Language: Crystal
- Size: 65.4 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# incremental_hmac
[](https://travis-ci.org/tlrasor/incremental_hmac)
The standard library's HMAC implementation is rather limited in that it can only work on data that has a `to_slice` method defined. This works fine for the typical web use cases for strings and byte buffers but does not scale well to calculating the HMAC of large files which are inconvenient to fit in memory.
This shard monkey patches OpenSSL::HMAC and adds an incremental interface modeled on Ruby's OpenSSL::HMAC class. It does this by calling into the same LibCrypto wrapper that the standard library does and should be "fairly safe" but I wouldn't advise it for production use at this time.
## Installation
1. Add the dependency to your `shard.yml`:
```yaml
dependencies:
incremental_hmac:
github: tlrasor/incremental_hmac
```
2. Run `shards install`
## Usage
```crystal
require "incremental_hmac"
## The incremental interface is an instance of HMAC
hmac = OpenSSL::HMAC.new(algorithm, key)
# get an IO/something that produces slices
File.open(path, "r") do |io|
data_slice = Bytes.new(8192)
loop do
read = io.read(data_slice)
break if read < 1
## Here we update the hmac with the current buffer
hmac << data_slice[0, read]
end
end
## Now just call digest or hexdigest to finalize
hmac.digest
```
Note, currently, HMAC digests can currently only be called once because the structure is finalized. This is somewhat a consequence of the backing C library and some thought needs to be put into how to solve this.
### Helpers
There are also some class method helpers which can handle reading the data in from a file
```crystal
key = ""
path = Path[""]
digest = OpenSSL::HMAC.hexdigest(OpenSSL::Algorithm::SHA256, key, path)
```
## Development
Do some dev and write some tests plz
## Contributing
1. Fork it ()
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Commit your changes (`git commit -am 'Add some feature'`)
4. Push to the branch (`git push origin my-new-feature`)
5. Create a new Pull Request
## Contributors
- [Travis Rasor](https://github.com/tlrasor) - creator and maintainer