Answer by Harish KM for Unable to send cloudwatch logs to loggly using a blueprint lambda - Invalid ciphertext

Follow these steps to fix InvalidCiphertextException:

1. Open the Lambda function in AWS console.

2. Scroll down to the Environment Variables section & click Edit:

3. Delete the value of kmsEncryptedCustomerToken& replace it with the customer token you got from https://<your-company>.loggly.com/tokens. The token looks like this: 72cf6d64-256e-449d-aabd-49e1f422ed58.

4. Expand the Encryption Configuration section at the bottom.

5. Select Enable helpers for encryption in transit.

6. Click the Encrypt button that appears next to kmsEncryptedCustomerToken.

7. Select the logglyCustomerToken KMS key (CMK) & Encrypt.

8. Finally, Save the environment variables.

The Lambda function test should succeed now. If you face any other issues or need a complete end-to-end screenshot-guided tutorial for the entire process of sending CloudWatch Logs to Loggly, please see my blog post.