AppUtils

Overview

Namespace containing AppUtils utilities

Functions

verifyAccountProof

Verifies the authenticity of an account proof signature on the Flow blockchain. Account proofs are cryptographic signatures used to prove ownership of a Flow account without revealing private keys. This function validates that the provided signatures were indeed created by the private keys associated with the specified Flow account address.

Import

You can import the entire package and access the function:

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import * as fcl from "@onflow/fcl-core"

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fcl.AppUtils.verifyAccountProof(appIdentifier, accountProofData, opts)

Or import the namespace directly:

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import { AppUtils } from "@onflow/fcl-core"

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AppUtils.verifyAccountProof(appIdentifier, accountProofData, opts)

Usage

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import * as fcl from "@onflow/fcl"

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const accountProofData = {

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address: "0x123",

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nonce: "F0123"

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signatures: [{f_type: "CompositeSignature", f_vsn: "1.0.0", addr: "0x123", keyId: 0, signature: "abc123"}],

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}

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const isValid = await fcl.AppUtils.verifyAccountProof(

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"AwesomeAppId",

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accountProofData,

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{fclCryptoContract}

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)

Parameters

appIdentifier

• Type: string
• Description: A unique identifier for your application. This is typically your app's name or domain and is included in the signed message to prevent replay attacks across different applications.

accountProofData

• Type:

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export interface AccountProofData {

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address: string

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nonce: string

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signatures: CompositeSignature[]

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}

opts (optional)

• Type:

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export interface VerifySignaturesScriptOptions {

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fclCryptoContract?: string

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}

• Description: Optional configuration parameters

Returns

Promise<boolean>

verifyUserSignatures

Verifies user signatures for arbitrary messages on the Flow blockchain. This function validates that the provided signatures were created by the private keys associated with the specified Flow account when signing the given message. This is useful for authenticating users or validating signed data outside of transaction contexts.

Import

You can import the entire package and access the function:

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import * as fcl from "@onflow/fcl-core"

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fcl.AppUtils.verifyUserSignatures(message, compSigs, opts)

Or import the namespace directly:

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import { AppUtils } from "@onflow/fcl-core"

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AppUtils.verifyUserSignatures(message, compSigs, opts)

Usage

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// Basic message signature verification

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import * as fcl from "@onflow/fcl"

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const originalMessage = "Hello, Flow blockchain!"

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const hexMessage = Buffer.from(originalMessage).toString("hex")

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const signatures = [{

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f_type: "CompositeSignature",

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f_vsn: "1.0.0",

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addr: "0x1234567890abcdef",

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keyId: 0,

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signature: "abc123def456..." // signature from user's wallet

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}]

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const isValid = await fcl.AppUtils.verifyUserSignatures(

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hexMessage,

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signatures

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)

Parameters

message

• Type: string
• Description: The message that was signed, encoded as a hexadecimal string. The original message should be converted to hex before passing to this function.

compSigs

• Type: CompositeSignature[]
• Description: Array of composite signatures to verify. All signatures must be from the same account address.

opts (optional)

• Type:

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export interface VerifySignaturesScriptOptions {

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fclCryptoContract?: string

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}

• Description: Optional configuration parameters

Returns

Promise<boolean>

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