openssl aes gcm

OpenSSL is a popular open-source library that provides cryptographic functions, including AES (Advanced Encryption Standard). AES-GCM (Galois/Counter Mode) is a mode of operation for AES that combines encryption and authentication. It provides both confidentiality and integrity.

To use AES-GCM with OpenSSL, you can follow these steps:

1. Install OpenSSL: If you don't have OpenSSL installed on your system, you can download and install it from the official OpenSSL website.

2. Generate a key and IV: AES-GCM requires a key and an initialization vector (IV). You can generate them using OpenSSL's command-line tool or programmatically using OpenSSL's library functions.

3. Encrypt data: Use the EVP (Envelope) interface provided by OpenSSL to perform AES-GCM encryption. Here's an example command-line invocation:

   openssl enc -aes-256-gcm -in plaintext.txt -out ciphertext.bin -K <key> -iv <iv>

Replace `<key>` with your AES-GCM key (in hexadecimal or base64 format) and `<iv>` with your IV. Replace `plaintext.txt` with the path to your plaintext file and `ciphertext.bin` with the desired output ciphertext file.

4. Decrypt data: To decrypt the ciphertext, use a similar command-line invocation:

   openssl enc -d -aes-256-gcm -in ciphertext.bin -out plaintext.txt -K <key> -iv <iv>

Make sure to use the same key and IV that were used for encryption.

Note that this is just a basic example, and there are more advanced options and features available in OpenSSL for AES-GCM encryption. You can refer to the OpenSSL documentation or seek further resources for more information.