This is an example of how to encrypt a file with NodeJS with AES in CTR mode and HMAC-SHA512.
The file_crypto.js is an ES6 class which handles the counter for the nonce automatically.
It also fails to encrypt in case it exceeded the maximum amount of blocks for its settings.
The total amount of blocks of 16 bytes size (128 bit), is: 2147483647
The maximum file size this NodeJS class is capable of handling is therefore:
2147483648 * 16bytes = ~32GB
after that, you will need to rotate the key (create a new instance of the FileCrypto class)
or keep the same key, but create a new instance of the FileCrypto class with a different random nonce.
Both methods are equivalent because the party receiving the file needs to know both the decryption key and the random nonce
used to initialise the FileCrypto class.
WARNING: If you re-use both the random nonce and the secret key the security is completely compromised!
The class can be extended to handle bigger files.
Please open an issue if you are interested about it.
Author
This library was written by Sec51 info@sec51.com.
The code in this repository is licensed under GNU General Public License v3.0. See LICENSE for the full license text.