Requirement Summary:

Prevent unauthorized code changes in AWS Lambda

Ensure only trusted code is deployed

AWS Lambda supports Code Signing:

You can configure code signing in Lambda using AWS Signer

Packages must be digitally signed and verified against the signing profile

Rejects unauthorized/modified packages automatically

Evaluate Options:

A. Trusted code option in CodeDeploy

No such feature exists for Lambda

CodeDeploy is more for EC2/On-Prem/Containers, not Lambda code signing

B. Define code signing config + use AWS Signer

This is exactly how AWS enforces trusted code deployment

Attach a code signing configuration to the Lambda function

Use AWS Signer to digitally sign deployment packages

C. Link to KMS to sign code

KMS is not used to sign Lambda packages

KMS is for data encryption, not application code integrity

D. Set KmsKeyArn

This configures data encryption, not code signing

Lambda code signing: https://docs.aws.amazon.com/lambda/latest/dg/configuration-codesigning.html

AWS Signer overview: https://docs.aws.amazon.com/signer/latest/developerguide/what-is-signer.html