Amazon提供了documentation来验证路由到HTTP/HTTPS端点的SNS消息是否有效。在服务器上使用Vapor和Swift，沿着swift-certificates和swift-crypto，我实现了验证逻辑：

func messageHasValidSignature<Message: VerifiableMessage>(_ message: Message) async throws -> Bool {
    guard let certificateBytes = try await client.get(.init(message.signingCertificateURL)).body else {
        logger.error("Failed to get signing certificate body")
        throw Abort(.badRequest)
    }
    let certificateString = String(buffer: certificateBytes)
    let certificate = try Certificate(pemEncoded: certificateString)
    let publicKey = try _RSA.Signing.PublicKey(derRepresentation: certificate.publicKey.subjectPublicKeyInfoBytes)
    guard let signatureData = Data(base64Encoded: message.signature) else {
        logger.error("Failed to decode signature")
        throw Abort(.badRequest)
    }
    let signature = _RSA.Signing.RSASignature(rawRepresentation: signatureData)
    guard let dataToSign = message.stringToSign.data(using: .utf8) else {
        logger.error("Failed to convert string to sign to data")
        throw Abort(.badRequest)
    }
    let digest: any Digest
    switch message.signatureVersion {
    case ._1:
        digest = Insecure.SHA1.hash(data: dataToSign)
    case ._2:
        digest = SHA256.hash(data: dataToSign)
    }
    return publicKey.isValidSignature(signature, for: digest)
}

字符串
我正在构造要签名的字符串如下：

extension SubscriptionConfirmationMessage: VerifiableMessage {
    var stringToSign: String {
        """
        Message
        \(message)
        MessageId
        \(messageID)
        SubscribeURL
        \(subscribeURL)
        Timestamp
        \(timestamp)
        Token
        \(token)
        TopicArn
        \(topicARN)
        Type
        SubscriptionConfirmation
        """
    }
}

型
但是isValidSignature总是返回false。如何正确验证消息？