AES-GCM Decrypt

Test the exact key, IV, ciphertext, and auth tag bytes before you blame the algorithm

Safety note: AES-GCM encryption and decryption stay in your browser. Treat keys and IVs as sensitive bytes, and keep the auth tag paired with the exact ciphertext it came from.

Decrypt an AES-GCM payloadPaste ciphertext, auth tag, key, and IV exactly as your app produced them, then confirm whether the bytes really decrypt

Use Load sample for a known-good decrypt, then swap in your own bytes when you need to debug a mismatch.

Key length

Key encoding

IV encoding

Ciphertext/tag encoding

AES key

Ciphertext

Auth tag

What It Encrypts

AES-GCM combines confidentiality and authentication. You need the exact key, IV, ciphertext, and auth tag bytes to get a successful decrypt. This page keeps those pieces visible instead of hiding them behind one opaque payload field.

Run the AES-GCM Workflow

Choose the same encoding your app or library already uses for keys, IVs, ciphertext, and tags.
Paste the ciphertext and the 16-byte auth tag separately, then click Decrypt with AES-GCM.
If decrypt fails, verify the encoding first, then confirm that the IV and tag came from the same encryption run.
Copy the individual values, not just the combined output, when you need to compare another implementation.

Why Exact Bytes Matter

The most common AES-GCM failures are byte mismatches, not algorithm mismatches. A hex key pasted as Base64, an IV with one missing byte, or a tag separated from the wrong ciphertext will all fail even though the mode name is “correct.”