AES-GCM Encrypt

Encrypt with explicit key, IV, AAD, tag length, ciphertext, and auth tag bytes

Encrypt with AES-GCMCreate ciphertext, auth tag, and combined output with explicit interoperability settings

Generate fresh values or paste known bytes to compare another implementation.

Key length

Key encoding

IV encoding

Output encoding

AES key

Masked by default. Keys are not added to the URL.

Use a unique IV for each encryption with the same key.

Plaintext

Ciphertext

Interoperability settings tag length and optional AAD

Auth tag length

AAD encoding

Additional authenticated data (AAD)

AAD is authenticated but not encrypted. Decryption needs the exact same AAD bytes, encoding, and tag length.

What AES-GCM Needs

AES-GCM authenticates the ciphertext and any optional AAD. Decryption needs the exact key, IV, ciphertext, tag, AAD, and tag length. The page keeps each byte-oriented setting visible so you can reproduce another implementation without guessing its payload format.

Run the AES-GCM Workflow

Choose the encodings and payload layout used by the other implementation.
Enter UTF-8 plaintext, then encrypt to get separate and combined outputs.
Open Interoperability settings only when you need a non-default tag length or AAD.
Store the IV and tag with the ciphertext; store the key separately.

Why AES-GCM Tag Verification Fails

A tag failure does not reveal which input is wrong. Check the byte encoding, IV, ciphertext/tag split, AAD, and tag length before assuming the key is wrong. In a combined payload, this tool treats the final selected tag-length bytes as the tag. A successful decrypt authenticates the complete set of inputs.