Crypto Tools
AES-GCM and RSA-OAEP encryption and decryption using the WebCrypto API
Uses PBKDF2 (100,000 iterations) to derive a 256-bit AES-GCM key
About this tool
The AES/RSA Encryption tool lets you encrypt and decrypt text in-browser using the Web Cryptography API. AES-GCM mode provides authenticated symmetric encryption — ideal for encrypting data with a password. RSA-OAEP provides asymmetric encryption with a generated key pair, useful for understanding public-key cryptography.
When to use it
- →Encrypting sensitive notes or config values before storing them
- →Learning how AES and RSA encryption work in practice
- →Testing encrypted payloads for API security implementations
- →Generating RSA key pairs for development and testing purposes
Tips
- ◆AES-GCM includes authentication — a tampered ciphertext will fail to decrypt, not silently produce garbage.
- ◆The password you provide is stretched using PBKDF2 before deriving the AES key — a weak password is still a security risk.
- ◆RSA is for encrypting small amounts of data (like an AES key). For large data, always use hybrid encryption: RSA + AES.
Frequently asked questions
What is the difference between AES-GCM and AES-CBC?
AES-GCM (Galois/Counter Mode) is an authenticated encryption mode — it simultaneously encrypts and produces an authentication tag. If the ciphertext is tampered with, decryption fails with an error. AES-CBC (Cipher Block Chaining) only encrypts — it provides no authentication, so tampering can go undetected. Always prefer AES-GCM for new implementations.
How secure is browser-based encryption?
The cryptographic operations themselves are as secure as any native application — this tool uses the browser's Web Crypto API, which calls the operating system's cryptographic primitives. The risk is in the environment: a compromised browser extension or XSS vulnerability could intercept your keys or plaintext. For highly sensitive data, use dedicated offline tools.
What is PBKDF2 and why is it used for password-based encryption?
PBKDF2 (Password-Based Key Derivation Function 2) turns a human-chosen password into a cryptographic key. It does this by hashing the password thousands of times (this tool uses 100,000 iterations of SHA-256), making brute-force attacks extremely slow. A password that takes 1 millisecond to hash would take 100 seconds for an attacker to test one guess at 100,000 iterations.
When should I use RSA vs AES encryption?
Use AES for encrypting data of any size with a shared secret or password. Use RSA for key exchange — to securely send an AES key to someone using their public key, without a pre-shared secret. In practice, hybrid encryption (generate a random AES key, encrypt data with AES, encrypt the AES key with RSA) combines both: RSA for the key exchange, AES for the bulk data.