class Crypto::Bcrypt

• Crypto::Bcrypt
• Reference
• Object

Overview

Pure Crystal implementation of the Bcrypt algorithm by Niels Provos and David Mazières, as presented at USENIX in 1999.

The algorithm has a maximum password length limit of 71 characters (see this comment on stackoverflow).

Refer to Crypto::Bcrypt::Password for a higher level interface.

About the Cost

Bcrypt, like the PBKDF2 or scrypt ciphers, are designed to be slow, so generating rainbow tables or cracking passwords is nearly impossible. Yet, computers are always getting faster and faster, so the actual cost must be incremented every once in a while. Always use the maximum cost that is tolerable, performance wise, for your application. Be sure to test and select this based on your server, not your home computer.

This implementation of Bcrypt is currently 50% slower than pure C solutions, so keep this in mind when selecting your cost. It may be wise to test with Ruby's bcrypt gem which is a binding to OpenBSD's implementation.

Last but not least: beware of denial of services! Always protect your application using an external strategy (eg: rate limiting), otherwise endpoints that verifies bcrypt hashes will be an easy target.

NOTE To use Bcrypt, you must explicitly import it with require "crypto/bcrypt"

Defined in:

Constant Summary

COST_RANGE = 4..31

DEFAULT_COST = 11

PASSWORD_RANGE = 1..72

SALT_SIZE = 16

Constructors

• .new(password : String, salt : String, cost = DEFAULT_COST)

  Creates a new Crypto::Bcrypt object from the given password with salt and cost.

• .new(password : Bytes, salt : Bytes, cost : Int32 = DEFAULT_COST)

  Creates a new Crypto::Bcrypt object from the given password with salt in bytes and cost.

Class Method Summary

• .hash_secret(password, cost = DEFAULT_COST) : String

  Hashes the password using bcrypt algorithm using salt obtained via Random::Secure.random_bytes(SALT_SIZE).

Instance Method Summary

• #cost : Int32
• #digest : Bytes
• #inspect(io : IO) : Nil

  Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.

• #password : Bytes
• #salt : Bytes
• #to_s(io : IO) : Nil

  Appends a short String representation of this object which includes its class name and its object address.

• #to_s : String

  Returns a nicely readable and concise string representation of this object, typically intended for users.

• #to_slice(*args, **options)
• #to_slice(*args, **options, &)

Constructor Detail

require "crypto/bcrypt"

password = Crypto::Bcrypt.new "secret", "salt_of_16_chars"
password.digest

require "crypto/bcrypt"

password = Crypto::Bcrypt.new "secret".to_slice, "salt_of_16_chars".to_slice
password.digest

Class Method Detail

require "crypto/bcrypt"

Crypto::Bcrypt.hash_secret "secret"

Instance Method Detail

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).to_s # => #<Person:0x10a199f20>