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enforce-verifier

Use enforce-verifier to enforce that a verifier plugin with the specified verifier-name is in scope.

Note that verifier plugins aren't implemented as Pact code. Instead, implementing a verifier plugin requires changes to the Chainweb protocol. For information about the design and implementation of verifier plugins, see KIP-0028: Pact Verifier Plugins.

Basic syntax​

To enforce that a specific verifier is in scope, use the following syntax:

(enforce-verifier verifier-name)

Arguments​

Use the following argument to specify the verifier-name for the enforce-verifier Pact function:

ArgumentTypeDescription
verifier-namestringSpecifies the name of the verifier to enforce.

Return value​

The enforce-verifier function returns a boolean value indicating whether the specified verifier is in scope.

Examples​

The following example demonstrates the use of a signed_list verifier plugin that verifies signatures against structured message data to ensure the integrity and authenticity of messages provided to the mod module in a smart contract.

(namespace "free")

(module mod GOV
  (defcap GOV () true)
  (defcap MSG-GUARD (msg:list dst-fin-id:string)
    (enforce-verifier "signed_list")
  )

  (defun inbox ()
    (with-capability 
      (MSG-GUARD [["issue","finp2p","citi:102:d0c3eb56-0fff-4670-adfd-ad291a4314c3",
           "finId","02fd7923740a775c95ce17e9bb7239ff9096689f70db9263a7efb9a9ad08e9fed7","1"]]
         "02fd7923740a775c95ce17e9bb7239ff9096689f70db9263a7efb9a9ad08e9fed7")
      )
      1)
)

In this example, the capability MSG-GUARD uses the enforce-verifier function with the signed_list verifier plugin. The arguments that are passed to the capability are then evaluated by the verifier to ensure the integrity and authenticity of the message. If verification passed to the plugin fails, the capability isn't granted and the transaction fails.

The following example illustrates using the enforce-verifier function in the capability definition, then using the env-verifiers function in the Pact REPL to add the "COOLZK" and "HYPERCHAIN-BRIDGE" verifier plugins to the environment data.

(module accounts GOV 
  (defcap GOV () true) 
  (defcap USER_GUARD (user:string) 
    (enforce-verifier "COOLZK"))
  (defun create-user (user:string)
    (with-capability USER_GUARD "rae")
  )
)
(module bridge GOV 
  (defcap GOV () true) 
  (defcap MINT (coin:string amount:integer) 
    (enforce-verifier "HYPERCHAIN_BRIDGE"))
)
(env-verifiers [{'name: "COOLZK", 'caps: [(accounts.USER_GUARD "my-account")]}, {'name: "HYPERCHAIN-BRIDGE", 'caps: [(bridge.MINT "mycoin" 20)]}])

In this example, the verifiers are loaded in the environment so that they are in scope for the enforce-verifier function:

enforce-verifier-test.repl:0:0-7:1:Trace: Loaded module accounts, hash NXmdjAMHjjJSh-JUwTlT0IsOwZiXg_ZytI8Q3B2Xz4o
enforce-verifier-test.repl:8:0-12:1:Trace: Loaded module bridge, hash E2h3NLl5ePmKGvd8aNvFHyo-LONVsbxHXg8giuY3kuc
enforce-verifier-test.repl:13:0-13:146:Trace: "Setting transaction verifiers/caps"
Load successful

If the required verifier plugins are in scope, the enforce-verifier function returns true. If a verifier is not in scope, the function fails.

pact> (enforce-verifier "COOLZK")
<interactive>:0:0:Error: Verifier failure COOLZK: not in transaction

The enforce-verifier function provides a way to ensure that a specific verifier is available for use within a Pact contract.

For more information about including verifier plugins in environment data for testing, see env-verifiers.