Hash & Crypto Helpers
Use a raw 128-, 192- or 256-bit key. Encryption creates a new nonce; decryption requires the matching tag and any AAD.
Message and key stay in this page’s memory; nothing is uploaded or saved to browser storage.
Mode: AES-GCM
Max 1 MiB input, 64 KiB AAD. Key 16/24/32 bytes; nonce 12 bytes; tag 16 bytes.
Enter a raw key; empty plaintext is allowed.
Use the AES-GCM encryption tool when two implementations produce different ciphertext or a received message fails authentication. Start with the actual key bytes, not a password that one service may derive differently.
This AES-GCM encryption tool keeps ciphertext, nonce and tag separate so you can compare each field with a protocol trace. It is an AES encrypt decrypt online check for one test message, not a key store or production protocol.
See the fields that decide whether a message can be decrypted.
The AES-GCM encryption tool generates a new 12-byte nonce for every normal encryption. The same plaintext and key therefore lead to different ciphertext and authentication tags; both fields are shown separately.
Alter a tag or use different AAD and authenticated decryption fails as a whole. The AES-GCM encryption tool never displays speculative partial plaintext after a failed check.
A 32-character Hex key is 16 bytes; the same characters as text would be 32 bytes. Choose Hex or standard Base64 and check for exactly 16, 24 or 32 decoded bytes.
Normal encryption draws a new 12-byte nonce on every run. Switch to manual nonce only to reproduce an existing vector; decryption always needs the original nonce and exactly the same AAD.
Load the NIST vector to test known ciphertext and a 128-bit tag. For an external message, paste ciphertext and tag separately; failed authentication identifies a mismatch without claiming which field caused it.
Key length is checked after Hex or Base64 decoding, never guessed from character count or silently padded.
Plaintext can be UTF-8 or Hex; ciphertext, nonce and tag can be Hex or Base64. An AES GCM authentication tag stays distinct from the ciphertext.
A NIST AES-128-GCM example loads exact test bytes and compares both ciphertext and tag, making an AES 256 encrypt decrypt online mismatch easier to isolate from presentation format.
This tool accepts a 12-byte nonce, the usual 96-bit GCM size. Keep it with the ciphertext and tag so the recipient can decrypt.
No. Normal encryption generates a fresh random nonce on every run. Manual nonce input exists only to reproduce known vectors or existing test data.
The key, nonce, AAD, ciphertext or tag may differ from the sender’s values. GCM cannot identify which one changed, and this page releases no plaintext after failure.
No. Supply the complete 16-byte tag alongside the ciphertext. This tool does not offer unauthenticated recovery or shorter tags.
Yes, if you already have a 32-byte raw key and use AES-GCM with matching nonce, tag and AAD. Password-based containers from other sites are not interchangeable.
Still have a question?
Load the public NIST vector, then replace it with your own test bytes. The AES-GCM encryption tool shows exactly which encoded fields must travel with the ciphertext.