macaroons4J  

How to add this dependency to your project

Basic usage example

Working with Macaroons in general

StringhintTargetLocation ="https://google.com";byte[]macaroonIdentifier =UUID.randomUUID().toString().getBytes(StandardCharsets.UTF_8);StringmacaroonSecret ="A secret, only known to the target location";Macaroonmacaroon =newSimpleMacaroon(macaroonSecret,macaroonIdentifier,hintTargetLocation);VerificationContextcontext =newVerificationContext();HashSet<VerificationContext>validContexts =macaroon.verify(macaroonSecret,context);assert(validContexts.size() >=1);

Working with first-party caveats

byte[]firstPartyCaveatIdentifier =UUID.randomUUID().toString().getBytes(StandardCharsets.UTF_8);// Create a custom FirstPartyCaveat subclass and define its verification process.FirstPartyCaveattimeConstraint =newFirstPartyCaveat(firstPartyCaveatIdentifier) {@Overrideprotectedvoidverify(@NotNullMacaroonmacaroon,@NotNullVerificationContextcontext)throwsIllegalStateException {/*            macaroon: the Macaroon instance that is being verified.            context: the context in which the caveat should hold.         */context.addRangeConstraint("time",Pair.of(5,10));    }};macaroon.addCaveat(timeConstraint);validContexts =macaroon.verify(macaroonSecret,context);assert(validContexts.size() >=1);context =newVerificationContext();context.addRangeConstraint("time",Pair.of(11,15));/*    No possible solutions here: context only valid in 'time' range 11 - 15, while the constraint is only valid between 5 - 10.    There is no overlapping between the two ranges. */validContexts =macaroon.verify(macaroonSecret,context);assert(validContexts.size() ==0);

Working with third-party caveats

StringthirdPartyCaveatRootKey ="Another secret, shared with the third-party";byte[]thirdPartyCaveatIdentifier ="user is Alice";StringhintDischargeLocation ="https://oauthprovider.com";ThirdPartyCaveatthirdPartyCaveat =newThirdPartyCaveat(thirdPartyCaveatRootKey,thirdPartyCaveatIdentifier,hintDischargeLocation);macaroon.addCaveat(thirdPartyCaveat);macaroon.verify(macaroonSecret,newVerificationContext());// Exception thrown: no discharge Macaroon bound.// You can add additional caveats to the discharge Macaroons, but we are not doing that here.MacaroondischargeMacaroon =newSimpleMacaroon(thirdPartyCaveatRootKey,thirdPartyCaveatIdentifier,hintDischargeLocation);macaroon.bindMacaroonForRequest(dischargeMacaroon);validContexts =macaroon.verify(macaroonSecret,newVerificationContext());assert(validContexts.size() >=1);

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