The Crystal One Time Password library. Use this to generate HOTP or TOTP codes for two factor authentication.
- Table of Contents
- Installation
- Usage
- Todo
- Running the project locally
- Contributing
- License
- Contributors
Add this to your application's shard.yml:
dependencies:
crotp:
github: philnash/crotprequire "crotp"
hotp = CrOTP::HOTP.new("secret")
counter = 1
# Generate a token
token = hotp.generate(counter)
# => "533881"
# Verify code
result = hotp.verify(token, counter)
# => truerequire "crotp"
totp = CrOTP::TOTP.new("secret")
# Generate a code at a specific time stamp (by default, #generate will make a
# code using Time.now)
token = totp.generate(at: 1484007247)
# => "020567"
# Verify code at a specific time stamp
result = totp.verify(token, at: 1484007247)
# => true
# Verify code at different time stamp, with allowed drift
result = totp.verify(token, at: 1484007299, allowed_drift: 1)
# => true
# Verify code at different time stamp, outside allowed drift
result = totp.verify(token, at: 1484007300, allowed_drift: 1)
# => falseAccording to RFC 6238 section 1.2:
TOTP implementations MAY use HMAC-SHA-256 or HMAC-SHA-512 functions, based on SHA-256 or SHA-512 hash functions, instead of the HMAC-SHA-1 function that has been specified for the HOTP computation in RFC4226.
To use either SHA-256 or SHA-512 as the hashing function, initialise your CrOTP::TOTP object with the algorithm you want:
require "crotp"
totp = CrOTP::TOTP.new("secret", algorithm: OpenSSL::Algorithm::SHA512)Note: authenticator applications may ignore the algorithm parameter when you encode your secret in a URL/QR code as below.
To share secrets with an authenticator application, like Authy or Google Authenticator you need a URI that you can share as a QR code. The implementation details for the URI are in the Google Authenticator wiki.
Here is how you can get the URI and, in case your user can't scan the code, the base 32 representation of the secret.
# For HOTP you need the initial counter and an issuer
puts hotp.authenticator_uri(initial_counter: 0, issuer: "Test app")
# => otpauth://hotp/Test%20app?secret=ONSWG4TFOQ&algorithm=SHA1&counter=0&digits=6&issuer=Test%20app
# You can add a user account detail too, normally an email address or username, that shows up in the authenticator app
puts hotp.authenticator_uri(initial_counter: 0, issuer: "Test app", user: "[email protected]")
# => otpauth://hotp/Test%20app:philnash%40example.com?secret=ONSWG4TFOQ&algorithm=SHA1&counter=0&digits=6&issuer=Test%20app# For TOTP you only need an issuer
puts totp.authenticator_uri(issuer: "Test app")
# => otpauth://totp/Test%20app?secret=ONSWG4TFOQ&algorithm=SHA1&period=30&digits=6&issuer=Test%20app
# You can add a user detail here too
puts totp.authenticator_uri(issuer: "Test app", user: "[email protected]")
# => otpauth://totp/Test%20app:philnash%40example.com?secret=ONSWG4TFOQ&algorithm=SHA1&period=30&digits=6&issuer=Test%20appputs hotp.base32_secret
# => ONSWG4TFOQ
puts totp.base32_secret
# => ONSWG4TFOQYou can see and run these examples and more in example/crotp.cr.
- Basic HOTP and TOTP generation and verification
- Rewrite
int_to_bytesand extract fromCrOTP::OTP - Verifying a token over a window of counters/time
- Google Authenticator otpauth URI generation
- Ability to choose algorithm (currently only sha1)
- Ability to choose size of period in TOTP
- Example application using Kemal
- Much more documentation
First clone the project:
git clone https://github.com/philnash/crotp.git
cd crotpRun the tests with:
crystal spec- Fork it ( https://github.com/philnash/crotp/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request
This code is available as open source under the terms of the MIT License.