Encrypt text with AES-GCM

Protect bytes with authenticated AES-GCM using a key, nonce, and optional associated data.

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ToolAES-GCM Encrypt
Input
Output
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Preview

How it works

AES-GCM processes plaintext, authenticates additional data, and appends an authentication tag to ciphertext. Decryption needs the same key, nonce, tag, and associated data to verify integrity.

  • A 96-bit nonce and 128-bit tag are interoperable defaults.
  • Nonce uniqueness is required for each key.

Worked example

Encrypt Message
Encrypt a message with a password using AES-256-GCM
Input
											Input: Secret message for Bob
Key: MySecretKey123!
Output
												2hubVho1RqIg33AizwYg+hO+QkQ5zxm9oBZZKS1/N6mOn+OAyCbbGoODxiEfbGJPRpN1mpj6MdkqiJHOYqAbRV1o

When to use this

Database fields, Web Crypto storage, and authenticated protocol messages use GCM.

Edge cases

  • Nonce reuse undermines GCM security.
  • Changing associated data causes authentication failure.
  • An altered or truncated tag must reject the message.

References