KMS decrypt using CustomSMSSender Lambda

[sudsbangs]

Hi,

I am trying to add a custom sms lambda trigger in cognito which would decrypt the code sent by cognito trigger when MFA has been enabled for user using KMS symmetric key. However i encounter the following issue Invoke Error {"errorType":"InvalidCiphertextException","errorMessage":"UnknownError" @aws-sdk/client-kms'. There are no sufficient documentation on how do we decrypt using v3 when the cognito sends an event to CustomSMSSender lambda.

Please see my sample code below:
export const customSMSSender = async ( event: any, context: APIGatewayEventRequestContext, callback: Callback ) => {
try {
const decryptInputParams: DecryptCommandInput = {
CiphertextBlob: Buffer.from(event.request.code, 'base64'),
};
const decryptCommand: DecryptCommand = new DecryptCommand( decryptInputParams );
const decryptRes = await kmsClient.send(decryptCommand);
} catch (e) {
// Error thrown as below {
"errorType": "InvalidCiphertextException", "errorMessage": "UnknownError", "name": "InvalidCiphertextException", "$fault": "client", "$metadata": { "httpStatusCode": 400, "requestId": "12345", "attempts": 1, "totalRetryDelay": 0 }, "__type": "InvalidCiphertextException", "message": "UnknownError",
}

[yenfryherrerafeliz]

Hi @sudsbangs, have you taken a look to the following documentation:

• https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-custom-email-sender.html#custom-email-sender-code-examples
• https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#symmetric-cmks

I hope this helps. Please let me know if you have any questions.

Thanks!

[ziaulrehman40]

So whatw as the issue?