It is not wrong. In AES-GCM, the "iv" is a nonce — any value (random, counter, cat picture) that is different for different encryptions with the same key. If yo

It is not wrong. In AES-GCM, the "iv" is a nonce — any value (random, counter, cat picture) that is different for different encryptions with the same key. If you use the key only for one encryption, as it is used here, it can be static (e.g. all zeros). BTW, regarding the AES comment: the authors of AES designed the block cipher, they didn't design the mode (GCM, which is CTR and GMAC). Nonce is a standard requirement for a stream cipher/stream mode of a block cipher/AEAD. In WebCrypto it's actually hard to skip setting the iv. And again, the author didn't make a mistake here.