AES Decrypt
Decrypt AES-256-GCM data produced by this site or any tool that follows the same format.
Decrypt AES-256-GCM data. Free, offline, runs entirely in your browser. Read more Show less
What is AES-GCM decryption?
This tool reverses the output of AES Encrypt. It reads the mode byte, salt (if present), IV, ciphertext, and GCM authentication tag, derives the same key, and returns the original plaintext.
If the ciphertext has been modified by even one byte, authentication fails and no plaintext is returned. This is a feature of AES-GCM: it detects tampering.
How to use
Paste the Base64 output from AES Encrypt. Choose the same key source (password or raw key). Enter the same key. The plaintext appears in the output.
FAQ
Why does decryption fail?
Two common causes: wrong password, or wrong mode (the tool tries to detect the mode byte automatically, but if you pasted data encrypted by another tool, the format may not match).
What if I used raw key mode?
Set Key Source to "Raw key" and paste the same 64-hex-character key used during encryption.
Is the plaintext sent to a server?
No. Decryption runs entirely in your browser.
How to verify
If decryption succeeds, the GCM authentication tag verified correctly. That means the ciphertext was not modified in transit and the password is correct. If it fails, either the password is wrong, the ciphertext was tampered with, or the two ends of the channel are using different settings.