A ruby implementation of the RFC 7519 OAuth JSON Web Token (JWT) standard.
If you have further questions related to development or usage, join us: ruby-jwt google group.
- Ruby 2.4 support was dropped in version 2.4.0
- Ruby 1.9.3 support was dropped at December 31st, 2016.
- Version 1.5.3 yanked. See: #132 and #133
See CHANGELOG.md for a complete set of changes.
Logo | Message |
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If you want to quickly add secure token-based authentication to Ruby projects, feel free to check Auth0's Ruby SDK and free plan at auth0.com/developers |
gem install jwt
Add the following to your Gemfile
gem 'jwt'
And run bundle install
The JWT spec supports NONE, HMAC, RSASSA, ECDSA and RSASSA-PSS algorithms for cryptographic signing. Currently the jwt gem supports NONE, HMAC, RSASSA and ECDSA. If you are using cryptographic signing, you need to specify the algorithm in the options hash whenever you call JWT.decode to ensure that an attacker cannot bypass the algorithm verification step. It is strongly recommended that you hard code the algorithm, as you may leave yourself vulnerable by dynamically picking the algorithm
See: JSON Web Algorithms (JWA) 3.1. "alg" (Algorithm) Header Parameter Values for JWS
- none - unsigned token
require 'jwt'
payload = { data: 'test' }
# IMPORTANT: set nil as password parameter
token = JWT.encode payload: payload, signer: JWT::Signer.new(nil, 'none')
# eyJhbGciOiJub25lIn0.eyJkYXRhIjoidGVzdCJ9.
puts token
# Set password to nil and validation to false otherwise this won't work
decoded_token = JWT.decode token, nil, false
# Array
# [
# {"data"=>"test"}, # payload
# {"alg"=>"none"} # header
# ]
puts decoded_token
- HS256 - HMAC using SHA-256 hash algorithm
- HS512256 - HMAC using SHA-512-256 hash algorithm (only available with RbNaCl; see note below)
- HS384 - HMAC using SHA-384 hash algorithm
- HS512 - HMAC using SHA-512 hash algorithm
# The secret must be a string. A JWT::DecodeError will be raised if it isn't provided.
hmac_secret = 'my$ecretK3y'
token = JWT.encode payload: payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
# eyJhbGciOiJIUzI1NiJ9.eyJkYXRhIjoidGVzdCJ9.pNIWIL34Jo13LViZAJACzK6Yf0qnvT_BuwOxiMCPE-Y
puts token
decoded_token = JWT.decode token, hmac_secret, true, { algorithm: 'HS256' }
# Array
# [
# {"data"=>"test"}, # payload
# {"alg"=>"HS256"} # header
# ]
puts decoded_token
Note: If RbNaCl is loadable, ruby-jwt will use it for HMAC-SHA256, HMAC-SHA512-256, and HMAC-SHA512. RbNaCl enforces a maximum key size of 32 bytes for these algorithms.
RbNaCl requires
libsodium, it can be installed
on MacOS with brew install libsodium
.
- RS256 - RSA using SHA-256 hash algorithm
- RS384 - RSA using SHA-384 hash algorithm
- RS512 - RSA using SHA-512 hash algorithm
rsa_private = OpenSSL::PKey::RSA.generate 2048
rsa_public = rsa_private.public_key
token = JWT.encode payload: payload, signer: JWT::Signer.new(rsa_private, 'RS256')
# eyJhbGciOiJSUzI1NiJ9.eyJkYXRhIjoidGVzdCJ9.GplO4w1spRgvEJQ3-FOtZr-uC8L45Jt7SN0J4woBnEXG_OZBSNcZjAJWpjadVYEe2ev3oUBFDYM1N_-0BTVeFGGYvMewu8E6aMjSZvOpf1cZBew-Vt4poSq7goG2YRI_zNPt3af2lkPqXD796IKC5URrEvcgF5xFQ-6h07XRDpSRx1ECrNsUOt7UM3l1IB4doY11GzwQA5sHDTmUZ0-kBT76ZMf12Srg_N3hZwphxBtudYtN5VGZn420sVrQMdPE_7Ni3EiWT88j7WCr1xrF60l8sZT3yKCVleG7D2BEXacTntB7GktBv4Xo8OKnpwpqTpIlC05dMowMkz3rEAAYbQ
puts token
decoded_token = JWT.decode token, rsa_public, true, { algorithm: 'RS256' }
# Array
# [
# {"data"=>"test"}, # payload
# {"alg"=>"RS256"} # header
# ]
puts decoded_token
- ES256 - ECDSA using P-256 and SHA-256
- ES384 - ECDSA using P-384 and SHA-384
- ES512 - ECDSA using P-521 and SHA-512
- ES256K - ECDSA using P-256K and SHA-256
ecdsa_key = OpenSSL::PKey::EC.generate('prime256v1')
token = JWT.encode payload: payload, signer: JWT::Signer.new(ecdsa_key, 'ES256')
# eyJhbGciOiJFUzI1NiJ9.eyJkYXRhIjoidGVzdCJ9.AlLW--kaF7EX1NMX9WJRuIW8NeRJbn2BLXHns7Q5TZr7Hy3lF6MOpMlp7GoxBFRLISQ6KrD0CJOrR8aogEsPeg
puts token
decoded_token = JWT.decode token, ecdsa_key, true, { algorithm: 'ES256' }
# Array
# [
# {"test"=>"data"}, # payload
# {"alg"=>"ES256"} # header
# ]
puts decoded_token
In order to use this algorithm you need to add the RbNaCl
gem to you Gemfile
.
gem 'rbnacl'
For more detailed installation instruction check the official repository on GitHub.
- ED25519
private_key = RbNaCl::Signatures::Ed25519::SigningKey.new('abcdefghijklmnopqrstuvwxyzABCDEF')
public_key = private_key.verify_key
token = JWT.encode payload: payload, signer: JWT::Signer.new(private_key, 'ED25519')
# eyJhbGciOiJFRDI1NTE5In0.eyJkYXRhIjoidGVzdCJ9.6xIztXyOupskddGA_RvKU76V9b2dCQUYhoZEVFnRimJoPYIzZ2Fm47CWw8k2NTCNpgfAuxg9OXjaiVK7MvrbCQ
puts token
decoded_token = JWT.decode token, public_key, true, { algorithm: 'ED25519' }
# Array
# [
# {"test"=>"data"}, # payload
# {"alg"=>"ED25519"} # header
# ]
In order to use this algorithm you need to add the openssl
gem to your Gemfile
with a version greater or equal to 2.1
.
gem 'openssl', '~> 2.1'
- PS256 - RSASSA-PSS using SHA-256 hash algorithm
- PS384 - RSASSA-PSS using SHA-384 hash algorithm
- PS512 - RSASSA-PSS using SHA-512 hash algorithm
rsa_private = OpenSSL::PKey::RSA.generate 2048
rsa_public = rsa_private.public_key
token = JWT.encode payload: payload, signer: JWT::Signer.new(rsa_private, 'PS256')
# eyJhbGciOiJQUzI1NiJ9.eyJkYXRhIjoidGVzdCJ9.KEmqagMUHM-NcmXo6818ZazVTIAkn9qU9KQFT1c5Iq91n0KRpAI84jj4ZCdkysDlWokFs3Dmn4MhcXP03oJKLFgnoPL40_Wgg9iFr0jnIVvnMUp1kp2RFUbL0jqExGTRA3LdAhuvw6ZByGD1bkcWjDXygjQw-hxILrT1bENjdr0JhFd-cB0-ps5SB0mwhFNcUw-OM3Uu30B1-mlFaelUY8jHJYKwLTZPNxHzndt8RGXF8iZLp7dGb06HSCKMcVzhASGMH4ZdFystRe2hh31cwcvnl-Eo_D4cdwmpN3Abhk_8rkxawQJR3duh8HNKc4AyFPo7SabEaSu2gLnLfN3yfg
puts token
decoded_token = JWT.decode token, rsa_public, true, { algorithm: 'PS256' }
# Array
# [
# {"data"=>"test"}, # payload
# {"alg"=>"PS256"} # header
# ]
puts decoded_token
JSON Web Token defines some reserved claim names and defines how they should be used. JWT supports these reserved claim names:
- 'exp' (Expiration Time) Claim
- 'nbf' (Not Before Time) Claim
- 'iss' (Issuer) Claim
- 'aud' (Audience) Claim
- 'jti' (JWT ID) Claim
- 'iat' (Issued At) Claim
- 'sub' (Subject) Claim
Ruby-jwt gem supports custom header fields
To add custom header fields you need to pass header_fields
parameter
token = JWT.encode payload: payload, signer: JWT::Signer.new(key, algorithm='HS256'), header_fields={}
Example:
require 'jwt'
payload = { data: 'test' }
# IMPORTANT: set nil as password parameter
token = JWT.encode payload: payload, signer: JWT::Signer.new(nil, 'none'), { typ: 'JWT' }
# eyJhbGciOiJub25lIiwidHlwIjoiSldUIn0.eyJkYXRhIjoidGVzdCJ9.
puts token
# Set password to nil and validation to false otherwise this won't work
decoded_token = JWT.decode token, nil, false
# Array
# [
# {"data"=>"test"}, # payload
# {"typ"=>"JWT", "alg"=>"none"} # header
# ]
puts decoded_token
From Oauth JSON Web Token 4.1.4. "exp" (Expiration Time) Claim:
The
exp
(expiration time) claim identifies the expiration time on or after which the JWT MUST NOT be accepted for processing. The processing of theexp
claim requires that the current date/time MUST be before the expiration date/time listed in theexp
claim. Implementers MAY provide for some smallleeway
, usually no more than a few minutes, to account for clock skew. Its value MUST be a number containing a NumericDate value. Use of this claim is OPTIONAL.
Handle Expiration Claim
exp = Time.now.to_i + 4 * 3600
exp_payload = { data: 'data', exp: exp }
token = JWT.encode payload: exp_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
decoded_token = JWT.decode token, hmac_secret, true, { algorithm: 'HS256' }
rescue JWT::ExpiredSignature
# Handle expired token, e.g. logout user or deny access
end
The Expiration Claim verification can be disabled.
# Decode token without raising JWT::ExpiredSignature error
JWT.decode token, hmac_secret, true, { verify_expiration: false, algorithm: 'HS256' }
Adding Leeway
exp = Time.now.to_i - 10
leeway = 30 # seconds
exp_payload = { data: 'data', exp: exp }
# build expired token
token = JWT.encode payload: exp_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# add leeway to ensure the token is still accepted
decoded_token = JWT.decode token, hmac_secret, true, { exp_leeway: leeway, algorithm: 'HS256' }
rescue JWT::ExpiredSignature
# Handle expired token, e.g. logout user or deny access
end
From Oauth JSON Web Token 4.1.5. "nbf" (Not Before) Claim:
The
nbf
(not before) claim identifies the time before which the JWT MUST NOT be accepted for processing. The processing of thenbf
claim requires that the current date/time MUST be after or equal to the not-before date/time listed in thenbf
claim. Implementers MAY provide for some smallleeway
, usually no more than a few minutes, to account for clock skew. Its value MUST be a number containing a NumericDate value. Use of this claim is OPTIONAL.
Handle Not Before Claim
nbf = Time.now.to_i - 3600
nbf_payload = { data: 'data', nbf: nbf }
token = JWT.encode payload: nbf_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
decoded_token = JWT.decode token, hmac_secret, true, { algorithm: 'HS256' }
rescue JWT::ImmatureSignature
# Handle invalid token, e.g. logout user or deny access
end
The Not Before Claim verification can be disabled.
# Decode token without raising JWT::ImmatureSignature error
JWT.decode token, hmac_secret, true, { verify_not_before: false, algorithm: 'HS256' }
Adding Leeway
nbf = Time.now.to_i + 10
leeway = 30
nbf_payload = { data: 'data', nbf: nbf }
# build expired token
token = JWT.encode payload: nbf_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# add leeway to ensure the token is valid
decoded_token = JWT.decode token, hmac_secret, true, { nbf_leeway: leeway, algorithm: 'HS256' }
rescue JWT::ImmatureSignature
# Handle invalid token, e.g. logout user or deny access
end
From Oauth JSON Web Token 4.1.1. "iss" (Issuer) Claim:
The
iss
(issuer) claim identifies the principal that issued the JWT. The processing of this claim is generally application specific. Theiss
value is a case-sensitive string containing a StringOrURI value. Use of this claim is OPTIONAL.
You can pass multiple allowed issuers as an Array, verification will pass if one of them matches the iss
value in the payload.
iss = 'My Awesome Company Inc. or https://my.awesome.website/'
iss_payload = { data: 'data', iss: iss }
token = JWT.encode payload: iss_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# Add iss to the validation to check if the token has been manipulated
decoded_token = JWT.decode token, hmac_secret, true, { iss: iss, verify_iss: true, algorithm: 'HS256' }
rescue JWT::InvalidIssuerError
# Handle invalid token, e.g. logout user or deny access
end
You can also pass a Regexp or Proc (with arity 1), verification will pass if the regexp matches or the proc returns truthy.
On supported ruby versions (>= 2.5) you can also delegate to methods, on older versions you will have
to convert them to proc (using to_proc
)
JWT.decode token, hmac_secret, true,
iss: %r'https://my.awesome.website/',
verify_iss: true,
algorithm: 'HS256'
JWT.decode token, hmac_secret, true,
iss: ->(issuer) { issuer.start_with?('My Awesome Company Inc') },
verify_iss: true,
algorithm: 'HS256'
JWT.decode token, hmac_secret, true,
iss: method(:valid_issuer?),
verify_iss: true,
algorithm: 'HS256'
# somewhere in the same class:
def valid_issuer?(issuer)
# custom validation
end
From Oauth JSON Web Token 4.1.3. "aud" (Audience) Claim:
The
aud
(audience) claim identifies the recipients that the JWT is intended for. Each principal intended to process the JWT MUST identify itself with a value in the audience claim. If the principal processing the claim does not identify itself with a value in theaud
claim when this claim is present, then the JWT MUST be rejected. In the general case, theaud
value is an array of case-sensitive strings, each containing a StringOrURI value. In the special case when the JWT has one audience, theaud
value MAY be a single case-sensitive string containing a StringOrURI value. The interpretation of audience values is generally application specific. Use of this claim is OPTIONAL.
aud = ['Young', 'Old']
aud_payload = { data: 'data', aud: aud }
token = JWT.encode payload: aud_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# Add aud to the validation to check if the token has been manipulated
decoded_token = JWT.decode token, hmac_secret, true, { aud: aud, verify_aud: true, algorithm: 'HS256' }
rescue JWT::InvalidAudError
# Handle invalid token, e.g. logout user or deny access
puts 'Audience Error'
end
From Oauth JSON Web Token 4.1.7. "jti" (JWT ID) Claim:
The
jti
(JWT ID) claim provides a unique identifier for the JWT. The identifier value MUST be assigned in a manner that ensures that there is a negligible probability that the same value will be accidentally assigned to a different data object; if the application uses multiple issuers, collisions MUST be prevented among values produced by different issuers as well. Thejti
claim can be used to prevent the JWT from being replayed. Thejti
value is a case-sensitive string. Use of this claim is OPTIONAL.
# Use the secret and iat to create a unique key per request to prevent replay attacks
jti_raw = [hmac_secret, iat].join(':').to_s
jti = Digest::MD5.hexdigest(jti_raw)
jti_payload = { data: 'data', iat: iat, jti: jti }
token = JWT.encode payload: jti_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# If :verify_jti is true, validation will pass if a JTI is present
#decoded_token = JWT.decode token, hmac_secret, true, { verify_jti: true, algorithm: 'HS256' }
# Alternatively, pass a proc with your own code to check if the JTI has already been used
decoded_token = JWT.decode token, hmac_secret, true, { verify_jti: proc { |jti| my_validation_method(jti) }, algorithm: 'HS256' }
# or
decoded_token = JWT.decode token, hmac_secret, true, { verify_jti: proc { |jti, payload| my_validation_method(jti, payload) }, algorithm: 'HS256' }
rescue JWT::InvalidJtiError
# Handle invalid token, e.g. logout user or deny access
puts 'Error'
end
From Oauth JSON Web Token 4.1.6. "iat" (Issued At) Claim:
The
iat
(issued at) claim identifies the time at which the JWT was issued. This claim can be used to determine the age of the JWT. Theleeway
option is not taken into account when verifying this claim. Theiat_leeway
option was removed in version 2.2.0. Its value MUST be a number containing a NumericDate value. Use of this claim is OPTIONAL.
Handle Issued At Claim
iat = Time.now.to_i
iat_payload = { data: 'data', iat: iat }
token = JWT.encode payload: iat_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# Add iat to the validation to check if the token has been manipulated
decoded_token = JWT.decode token, hmac_secret, true, { verify_iat: true, algorithm: 'HS256' }
rescue JWT::InvalidIatError
# Handle invalid token, e.g. logout user or deny access
end
From Oauth JSON Web Token 4.1.2. "sub" (Subject) Claim:
The
sub
(subject) claim identifies the principal that is the subject of the JWT. The Claims in a JWT are normally statements about the subject. The subject value MUST either be scoped to be locally unique in the context of the issuer or be globally unique. The processing of this claim is generally application specific. The sub value is a case-sensitive string containing a StringOrURI value. Use of this claim is OPTIONAL.
sub = 'Subject'
sub_payload = { data: 'data', sub: sub }
token = JWT.encode payload: sub_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# Add sub to the validation to check if the token has been manipulated
decoded_token = JWT.decode token, hmac_secret, true, { sub: sub, verify_sub: true, algorithm: 'HS256' }
rescue JWT::InvalidSubError
# Handle invalid token, e.g. logout user or deny access
end
To dynamically find the key for verifying the JWT signature, pass a block to the decode block. The block receives headers and the original payload as parameters. It should return with the key to verify the signature that was used to sign the JWT.
issuers = %w[My_Awesome_Company1 My_Awesome_Company2]
iss_payload = { data: 'data', iss: issuers.first }
secrets = { issuers.first => hmac_secret, issuers.last => 'hmac_secret2' }
token = JWT.encode payload: iss_payload, signer: JWT::Signer.new(hmac_secret, 'HS256')
begin
# Add iss to the validation to check if the token has been manipulated
decoded_token = JWT.decode(token, nil, true, { iss: issuers, verify_iss: true, algorithm: 'HS256' }) do |_headers, payload|
secrets[payload['iss']]
end
rescue JWT::InvalidIssuerError
# Handle invalid token, e.g. logout user or deny access
end
You can specify claims that must be present for decoding to be successful. JWT::MissingRequiredClaim will be raised if any are missing
# Will raise a JWT::MissingRequiredClaim error if the 'exp' claim is absent
JWT.decode token, hmac_secret, true, { required_claims: ['exp'], algorithm: 'HS256' }
A JWT signature can be verified using certificate(s) given in the x5c
header. Before doing that, the trustworthiness of these certificate(s) must be established. This is done in accordance with RFC 5280 which (among other things) verifies the certificate(s) are issued by a trusted root certificate, the timestamps are valid, and none of the certificate(s) are revoked (i.e. being present in the root certificate's Certificate Revocation List).
root_certificates = [] # trusted `OpenSSL::X509::Certificate` objects
crl_uris = root_certificates.map(&:crl_uris)
crls = crl_uris.map do |uri|
# look up cached CRL by `uri` and return it if found, otherwise continue
crl = Net::HTTP.get(uri)
crl = OpenSSL::X509::CRL.new(crl)
# cache `crl` using `uri` as the key, expiry set to `crl.next_update` timestamp
end
begin
JWT.decode(token, nil, true, { x5c: { root_certificates: root_certificates, crls: crls })
rescue JWT::DecodeError
# Handle error, e.g. x5c header certificate revoked or expired
end
JWK is a JSON structure representing a cryptographic key. Currently only supports RSA, EC and HMAC keys. The jwks
option can be given as a lambda that evaluates every time a kid is resolved.
If the kid is not found from the given set the loader will be called a second time with the kid_not_found
option set to true
. The application can choose to implement some kind of JWK cache invalidation or other mechanism to handle such cases.
jwk = JWT::JWK.new(OpenSSL::PKey::RSA.new(2048), 'optional-kid')
payload = { data: 'data' }
headers = { kid: jwk.kid }
token = JWT.encode(payload: payload, signer: JWT::Signer.new(jwk.keypair, 'RS512'), header_fields: headers)
# The jwk loader would fetch the set of JWKs from a trusted source,
# to avoid malicious requests triggering cache invalidations there needs to be some kind of grace time or other logic for determining the validity of the invalidation.
# This example only allows cache invalidations every 5 minutes.
jwk_loader = ->(options) do
if options[:kid_not_found] && @cache_last_update < Time.now.to_i - 300
logger.info("Invalidating JWK cache. #{options[:kid]} not found from previous cache")
@cached_keys = nil
end
@cached_keys ||= begin
@cache_last_update = Time.now.to_i
{ keys: [jwk.export] }
end
end
begin
JWT.decode(token, nil, true, { algorithms: ['RS512'], jwks: jwk_loader })
rescue JWT::JWKError
# Handle problems with the provided JWKs
rescue JWT::DecodeError
# Handle other decode related issues e.g. no kid in header, no matching public key found etc.
end
or by passing the JWKs as a simple Hash
jwks = { keys: [{ ... }] } # keys accepts both of string and symbol
JWT.decode(token, nil, true, { algorithms: ['RS512'], jwks: jwks})
The ::JWT::JWK class can be used to import and export both the public key (default behaviour) and the private key. To include the private key in the export pass the include_private
parameter to the export method.
jwk = JWT::JWK.new(OpenSSL::PKey::RSA.new(2048))
jwk_hash = jwk.export
jwk_hash_with_private_key = jwk.export(include_private: true)
The key id (kid) generation in the gem is a custom algorithm and not based on any standards. To use a standardized JWK thumbprint (RFC 7638) as the kid for JWKs a generator type can be specified in the global configuration or can be given to the JWK instance on initialization.
JWT.configuration.jwk.kid_generator_type = :rfc7638_thumbprint
# OR
JWT.configuration.jwk.kid_generator = ::JWT::JWK::Thumbprint
# OR
jwk = JWT::JWK.new(OpenSSL::PKey::RSA.new(2048), kid_generator: ::JWT::JWK::Thumbprint)
jwk_hash = jwk.export
thumbprint_as_the_kid = jwk_hash[:kid]
We depend on Bundler for defining gemspec and performing releases to rubygems.org, which can be done with
rake release
The tests are written with rspec. Appraisal is used to ensure compatibility with 3rd party dependencies providing cryptographic features.
bundle install
bundle exec appraisal rake test
See CONTRIBUTING.
See AUTHORS.
See LICENSE.