Text Encrypt / Decrypt

When you need to share a password, an API key, or a private note through an untrusted channel — a public Slack, an email thread, a shared document — symmetric encryption gives the recipient the ability to decode it without exposing the plaintext along the way. This tool implements AES-256-GCM, a mode of the Advanced Encryption Standard that provides both confidentiality and authentication, meaning a tampered ciphertext will fail to decrypt rather than produce garbled output.

The tool uses the native Web Crypto API built into every modern browser and never sends any data to a server. The passphrase is processed through PBKDF2 with 100,000 iterations of SHA-256 to derive a 256-bit encryption key, which slows down brute-force attacks on weak passphrases. The output is Base64-encoded so it can be safely copied into emails, JSON fields, or any text channel. Use cases include encrypting credentials before committing them to a repository, sending private notes over unencrypted channels, and creating encrypted backups of sensitive strings.

This is genuine cryptography rather than an obfuscation trick. Your passphrase is stretched into a 256-bit key using PBKDF2 with SHA-256 over 100,000 iterations against a random 16-byte salt, and the message is then encrypted with AES-GCM using a random 12-byte initialisation vector. Salt, IV, and ciphertext are packed together and base64-encoded so the result is one copyable string.

Each element earns its place. The salt means the same passphrase produces a different key every time, so identical messages do not yield identical output and precomputed tables are useless. The iteration count makes each guess expensive for anyone attacking the passphrase by brute force. GCM is an authenticated mode, so decryption fails outright if the ciphertext has been altered rather than silently returning corrupted text.

All of it runs through the browser's Web Crypto implementation, on your machine. Neither the message nor the passphrase is transmitted.

Strong cryptography with a weak passphrase is weak. AES-256 is not going to be broken, so an attacker will attack the passphrase instead — and 100,000 PBKDF2 iterations raise the cost per guess without making a dictionary word safe. Use a long, random passphrase, and a series of unrelated words is both stronger and easier to remember than a short string of substituted characters.

Losing the passphrase means losing the data. There is no recovery mechanism, no backdoor, and no reset: that is the point of the design, and it is worth understanding before encrypting something you cannot afford to lose. Storing the passphrase in a password manager is the sensible approach.

Two limits on scope. Getting the ciphertext to someone else securely is a separate problem this does not solve — sending the passphrase alongside the message defeats the exercise, so use a different channel. And this encrypts a block of text, not files, and it is not a substitute for full-disk encryption, an encrypted messenger, or a password manager. For sustained confidential communication, use a tool designed for it.