https://github.com/spider-gazelle/HKDF

HMAC-based Extract-and-Expand Key Derivation Function (HKDF) for crystal lang
https://github.com/spider-gazelle/HKDF

Last synced: about 2 months ago
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HMAC-based Extract-and-Expand Key Derivation Function (HKDF) for crystal lang

• Host: GitHub
• URL: https://github.com/spider-gazelle/HKDF
• Owner: spider-gazelle
• License: mit
• Created: 2023-10-12T13:08:58.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2023-10-12T20:51:32.000Z (9 months ago)
• Last Synced: 2024-02-01T15:50:03.150Z (5 months ago)
• Language: Crystal
• Size: 5.86 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Lists

• awesome-crystal - HKDF - HMAC-based Extract-and-Expand Key Derivation Function [rfc5869](https://www.rfc-editor.org/rfc/rfc5869) (Algorithms and Data structures)

README

        
# HMAC-based Extract-and-Expand Key Derivation Function (HKDF)

HKDF is designed to be a relatively straightforward way to derive keys from one or more pieces of input data.

HKDF follows the "extract-then-expand" paradigm, where it extracts a fixed-size key from the input (possibly randomizing it in the process), and then expands it to the desired length.

## Key Derivation Function (KDF) Overview

A Key Derivation Function is used to derive cryptographic keys from secret values such as passwords or other keys.

The derived keys can then be used for various cryptographic purposes, such as encryption or authentication.

A primary use case of KDFs is to take non-uniformly distributed secret data (like user passwords) and produce a uniformly distributed secret key. KDFs can also be used to derive multiple keys from a single secret value, allowing for keys with different purposes to be generated from a single source.

HKDF, in particular, follows the "extract-then-expand" paradigm:

1. Extract: Take any input of potentially any length and produce a fixed-size pseudorandom key from it.

2. Expand: Take the aforementioned key and produce one or more keys of the desired length.

## Installation

1. Add the dependency to your `shard.yml`:

   ```yaml

   dependencies:

     hkdf:

       github: spider-gazelle/hkdf

   ```

2. Run `shards install`

## Usage

```crystal

require "hkdf"

require "random"

# Extract phase

salt = Random.new.random_bytes(16)

ikm = "input key material".to_slice # Your input key material

prk = HKDF.extract(salt, ikm)

# Expand phase

info = "some context".to_slice # Optional context and application-specific information

length = 32 # Desired length of the output keying material

okm = HKDF.expand(prk, info, length)

# Combined HKDF Extract-and-Expand

derived_key = HKDF.derive_key(salt, ikm, info, length)

derived_key == okm

```

## Contributors

- [Stephen von Takach](https://github.com/stakach) - creator and maintainer