Bcrypt Hasher Wrapper (Go-Hasher)

This project is a simple wrapper for the golang.org/x/crypto/bcrypt library. It was developed exclusively for personal study purposes, focusing on abstracting hashing logic and implementing interfaces in Go.

Objective

The package provides a standardized interface for generating and comparing hashes, making it easier to replace implementations or mock behaviors in unit tests.

Features

• Generate bcrypt hashes from byte slices.
• Validate passwords against existing hashes.
• Custom error handling.
• Automatic validation of the algorithm's cost.

Interface

The package exposes the following interface:

type Hasher interface {
    Generate(password []byte) ([]byte, error)
    Compare(hash, password []byte) error
}

Usage Example

Initialization

To create a new instance with the default cost:

h := hasher.New(hasher.DefaultCost)

Generating a Hash

password := []byte("my_secure_password")
hash, err := h.Generate(password)
if err != nil {
    // handle error
}

Comparing a Password

err := h.Compare(hash, []byte("my_secure_password"))
if err != nil {
    // if the error is "hasher: invalid password", the password is incorrect
}

Cost Constants

The wrapper exposes bcrypt cost constants for easier configuration:

• MinCost: 4
• MaxCost: 31
• DefaultCost: 10

Limitations

As per the Go bcrypt implementation, the maximum password length is 72 bytes. If a larger password is sent to the Generate method, the bcrypt.ErrPasswordTooLong error will be returned.

Contributing

Even though this is a personal study project, contributions are highly appreciated! Feel free to submit Pull Requests at any time to improve features, refactor code, or add new capabilities.