bch

A simple command-line tool for generating and verifying bcrypt password hashes.

Features

• Generate bcrypt hashes from passwords with configurable work factor
• Verify passwords against existing bcrypt hashes
• Secure password input (no echo to terminal)
• Fast and lightweight

Installation

Prerequisites

• Go 1.25.0 or later

Install from source

go install github.com/cemcatik/bch@latest

Or clone and build locally:

git clone https://github.com/cemcatik/bch.git
cd bch
go build -o bch bch.go

Usage

Generate a hash

Generate a bcrypt hash with the default work factor (12):

bch hash

You'll be prompted to enter a password, which will be hashed and printed to stdout.

Generate a hash with custom work factor

Use the -f or --factor flag to specify a different work factor:

bch hash --factor 14

Work factor guidelines:

• Default: 12 (recommended for most applications)
• Higher values = more secure but slower
• Each increment doubles the computational cost
• Range: 4-31 (bcrypt limitation)

Verify a hash

Verify a password against an existing bcrypt hash:

bch verify '$2a$12$R9h/cIPz0gi.URNNX3kh2OPST9/PgBkqquzi.Ss7KIUgO2t0jWMUW'

You'll be prompted to enter a password. The tool will print true if the password matches, or false if it doesn't.

Examples

Example: Generate hash

$ bch hash
Enter password:
$2a$12$R9h/cIPz0gi.URNNX3kh2OPST9/PgBkqquzi.Ss7KIUgO2t0jWMUW

Example: Generate hash with work factor 14

$ bch hash -f 14
Enter password:
$2a$14$xyz...

Example: Verify hash (correct password)

$ bch verify '$2a$12$R9h/cIPz0gi.URNNX3kh2OPST9/PgBkqquzi.Ss7KIUgO2t0jWMUW'
Enter password:
true

Example: Verify hash (incorrect password)

$ bch verify '$2a$12$R9h/cIPz0gi.URNNX3kh2OPST9/PgBkqquzi.Ss7KIUgO2t0jWMUW'
Enter password:
false

Security Notes

• Passwords are read securely from stdin without echoing to the terminal
• The default work factor of 12 is considered secure for most applications as of 2025
• Bcrypt automatically handles salting - each hash is unique even for the same password
• Higher work factors provide better protection against brute-force attacks but increase CPU usage

Development

Build

go build -o bch bch.go

Format code

go fmt ./...

Update dependencies

go get -u ./...
go mod tidy

License

MIT License - see LICENSE file for details.