***[ehochx says this on reddit:](https://www.reddit.com/r/crypto/comments/73o1bd/web_crypto_api_basic_encryption_correct_usage/dnryoee/)*** > *I'm not sure how AES-GCM is implemented, is the tag appended automatically? If not, the cipher text is malleable* ***[RenThraysk says:](https://www.reddit.com/r/crypto/comments/73o1bd/web_crypto_api_basic_encryption_correct_usage/dns2qyx/)*** > *Tag is appended automatically. So not an issue.*