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Authentication with JSON Web Tokens

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01 API AUTHENTICATION

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CLIENT SERVER [email protected]&PASSWORD=PASS123 AUTH_TOKEN=RAND0M$TR1N6

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CLIENT SERVER ARTICLES?AUTH_TOKEN=RAND0M$TR1N6

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02 SINGLE AUTH TOKEN PER USER

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id email password_digest auth_token 1 [email protected] $2a$10$5FkD.. 23ZS921a USERS TABLE

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GENERATE A RANDOM AUTH TOKEN class User before_save :generate_auth_token def generate_auth_token loop do self.auth_token = Devise.friendly_token break if User.find_by_auth_token(auth_token).nil? end end end

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PROBLEMS WITH THE SINGLE AUTH TOKEN APPROACH

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NAIVE IMPLEMENTATIONS NEVER EXPIRE THEM

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STORING IT IN PLAIN TEXT

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ISN’T THAT THE SAME AS STORING PASSWORDS IN PLAIN TEXT?

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NOT QUITE

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• difficult to change • used across several services PASSWORDS

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• easy to change • auto-generated, random, unique • not used across several services AUTH TOKENS

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03 SINGLE HASHED AUTH TOKEN PER USER

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NOT STORING IT IN PLAIN TEXT

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BROWSER SERVER EM AIL=DAM IR@ EXAM PLE.COM &PASSW ORD=PASS123 AUTH_TOKEN=RAND0M $TR1N6 EM AIL=DAM IR@ EXAM PLE.COM &PASSW ORD=PASS123 MOBILE AUTH_TOKEN=ANOTHER-RAND0M $TR1N6

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04 MULTIPLE HASHED AUTH TOKENS PER USER

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user_id token_digest 1 $2a$10$5FkD.. 2 $3R$D9S21$.. 1 $23$2sBPSA.. AUTH TOKENS TABLE

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ERASE TOKENS PERIODICALLY

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0Rel STORE TOKENS NOWHERE WHAT IF WE DIDN’T STORE THEM ANYWHERE?

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LET’S DO SOMETHING SIMILAR TO RAILS SESSIONS!

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05 RAILS SESSION STORAGE

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CLIENT SERVER [email protected]&PASSWORD=PASS123 SET-COOKIE: APP_SESSION=23OFSKL932RDASDAFSFJ23

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session[:user_id] = current_user.id

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sign(encrypt(hash))

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CLIENT SERVER APP_SESSION=23OFSKL932RDASDAFSFJ23

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decrypt(verify_signature(cookie))

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User.find(session[:user_id])

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WE COULD DO SOMETHING SIMILAR… … OR FOLLOW AN OPEN STANDARD

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06 JSON WEB TOKENS

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JSON Web Tokens are an open standard that defines a compact and self-contained way to securely share information between parties as a JSON Object.

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CLIENT SERVER [email protected]&PASSWORD=PASS123 AUTH_TOKEN=33WE.DAS3Q.ADAS

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TO THE API CONSUMER IT CAN LOOK RANDOM..

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..BUT IT’S MUCH MORE

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IT STORES INFORMATION INSIDE OF IT.

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DATA + SIGNATURE

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DATA + SIGNATURE data = { "user_id": 231 } token = data + sign(data)

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ABASASD.U93RJADSF.ASASD

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ABASASD.U93RJADSF.ASASD HEADER.PAYLOAD.SIGNATURE

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THE JWT HEADER

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{ "typ": "JWT", "alg": "HS256" } HEADER

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eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9 BASE64 ENCODED HEADER

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THE JWT BODY

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{ “user_id": 231, "exp": 1300819380, } BODY

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eyJpc3MiOiJzY290Y2guaW8iLCJleHAiOjE BASE64 ENCODED BODY

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THE JWT SIGNATURE

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encoded_string = Base64.encode64(header) + "." + Base64.encode64(payload); OpenSSL::HMAC.hexdigest( OpenSSL::Digest.new(‘sha256'), Rails.application.secrets.secret_key_base, encoded_string ) GENERATE A SIGNATURE

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SIGNATURE 03f329983b86f7d9a9f5fef85305880101d

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JSON WEB TOKEN eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.e yJpc3MiOiJzY290Y2guaW8iLCJleHAiOjE. 03f329983b86f7d9a9f5fef85305880101d

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iss: The issuer of the token sub: The subject of the token exp: This will define the expiration in NumericDate value. nbf: Defines the time before which the JWT MUST NOT be accepted for processing iat: The time the JWT was issued. Can be used to determine the age of the JWT BODY CLAIMS

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08 JWT <> RAILS SESSIONS

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RAILS SESSIONS ARE ENCRYPTED JWT’S ARE SIGNED

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RAILS SESSIONS CAN’T BE READ ON THE CLIENT SIDE JWT’S CAN BE READ ON THE CLIENT SIDE

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SECRET INFORMATION IN JWT’S MUST BE EXPLICITLY ENCRYPTED

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09 STATELESS AUTH

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{ “user_id": 231 } BODY

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FORCE LOGOUT / ACCOUNT HIJACKING

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10 REVOCATION

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HOW DOES DEVISE HANDLE THIS?

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INSERT A PART OF THE USERS PASSWORD HASH INTO THE PAYLOAD

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SESSION['WARDEN.USER.KEY'] [[1], "$2A$11$NNJPSD1Q36CG.PSQKPBU/U"]

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{ "exp": 1300819380, “user_id": 1, “pwd_start": $2a$11$nnjPSD1q36Cg.PSqKPBU }

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DISABLE TOKENS WITH AN IAT CLAIM OLDER THAN 6.10.2017

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{ “user_id": 231, "exp": 1300819380, "iat": 1300700011, } BODY

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id email password min_issued_at 1 [email protected] $2a$10$5FkD.. 2017-09-09 08:59:06.750087

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JTI JSON TOKEN IDENTIFIER

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{ "exp": 1300819380, "jti": 0A212BXC12, } BODY

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id email password jti 1 [email protected] $2a$10$5FkD.. DSAY039R21S

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LOGOUTS DON’T INVALIDATE TOKENS

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10 JWT ADVANTAGES

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SAFELY SHARE DATA WITH THE CLIENT APP

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{ “user_id": 231, "admin": true, “permissions”: [‘read’, ‘write’] }

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SELF CONTAINED TIME-BASED EXPIRATION HANDLING

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SCALABILITY

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MICROSERVICES INFORMATION SHARING

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NOT REINVENTING THE WHEEL - USING AN OPEN STANDARD.

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LANGUAGE SUPPORT

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JWT.IO RUBY, ELIXIR, GO, PYTHON, JAVA, RUST..

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11 RAILS IMPLEMENTATIONS

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CONCLUSIONS

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SCALABILITY. SIMPLICITY. STANDARDIZATION.

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ALWAYS IMPLEMENT A REVOCATION TECHNIQUE

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NO SILVER BULLET.

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Damir Svrtan Rails Team Lead @ infinum.co Organizer @ Ruby Zagreb Hit me up on twitter @DamirSvrtan