What algorithm does browser-based text encryption use?

AES-256-GCM (Galois/Counter Mode) with PBKDF2 key derivation (SHA-256, 100,000 iterations). A random 16-byte salt and 12-byte IV are generated per encryption. This is the same cipher used in TLS 1.3, Signal, and modern password managers.

Is client-side encryption actually secure?

Yes — the cryptographic strength of AES-256-GCM is not weakened by running it in a browser. The key is derived from your password locally via the browser's SubtleCrypto API. Security depends on password strength; weak passwords produce weak encryption regardless of the cipher.

How is client-side encryption different from encryption-as-a-service?

An encryption service receives your plaintext on a server, encrypts it, and returns the ciphertext — you must trust the operator not to log your data. A browser-based tool performs all cryptographic operations locally; the server never sees your plaintext or password.

Can I decrypt this with another tool?

Yes. The output format is base64(salt[16] + IV[12] + AES-256-GCM ciphertext). Any implementation using AES-256-GCM + PBKDF2 (SHA-256, 100k iterations) with the same parameter layout can decrypt it.

guide

How to Encrypt Text in Your Browser Using AES-256 (2026)

Last updated: 11 June 2026

To encrypt text privately, use a tool that runs AES-256-GCM encryption entirely in your browser via the Web Crypto API — no data is transmitted to a server. Open DevTools → Network tab before encrypting and verify that zero requests go out while you type your text and password. Most encryption-as-a-service tools send your plaintext to a backend; a client-side tool performs all cryptographic operations locally.

Step-by-step: encrypt text without uploading

Open DevTools (F12 → Network tab) to verify no data is transmitted during encryption.
Navigate to brevio Text Encryptor and select the Encrypt tab.
Enter the text you want to encrypt in the plaintext field, then enter a strong password.
Click Encrypt. The base64-encoded ciphertext appears immediately — no round-trip to any server.
Verify the Network tab shows zero outbound requests while you were typing. All cryptographic operations ran in the browser via crypto.subtle.
Copy the ciphertext — it is safe to store in a note, paste in a message, or save to a file. It is meaningless without your password.

To decrypt

Select the Decrypt tab.
Paste the ciphertext and enter the original password.
Click Decrypt to recover the plaintext.

What algorithm is used?

The tool uses AES-256-GCM (Advanced Encryption Standard, 256-bit key, Galois/Counter Mode) — the same cipher used in TLS 1.3, Signal, and most modern password managers. The key is never stored; it is derived fresh from your password on each operation using PBKDF2.

Full technical specification

Parameter	Value
Cipher	AES-256-GCM
Key derivation	PBKDF2
KDF hash	SHA-256
KDF iterations	100,000
Salt length	16 bytes (random per encryption)
IV length	12 bytes (random per encryption)
Output encoding	Base64
Output format	base64(salt[16] + IV[12] + ciphertext)

What makes client-side encryption different?

Encryption-as-a-service tools (online encryptors backed by a server) require you to trust that the operator does not log your plaintext or key material. A browser-based tool using the Web Crypto API removes this trust requirement entirely: the browser's built-inSubtleCrypto implementation performs the cryptography locally, and the operator's server never sees your data.

Encrypt and decrypt text from the command line

For scripting or CI workflows, OpenSSL provides equivalent functionality locally:

# Encrypt
openssl enc -aes-256-gcm -pbkdf2 -iter 100000 -salt \
  -in plaintext.txt -out encrypted.bin -pass pass:YourPassword

# Decrypt
openssl enc -d -aes-256-gcm -pbkdf2 -iter 100000 \
  -in encrypted.bin -out decrypted.txt -pass pass:YourPassword

The browser tool and OpenSSL use different binary container formats, so they are not directly interoperable — use one or the other consistently within a workflow.

Password security considerations

Entropy matters more than length. A random 16-character password from a password manager is far stronger than a memorable 30-character phrase.
Never reuse the password. If your password is exposed elsewhere, the encryption provides no protection.
Store the password separately from the ciphertext. Keeping both together defeats the purpose of encryption.
The ciphertext changes on every encryption. Encrypting the same plaintext twice produces different output because a new random salt and IV are generated each time.

Use cases

Storing API keys or secrets in a notes app without plaintext exposure
Transmitting sensitive text over an unencrypted channel (email, Slack) with a shared password
Creating encrypted backups of seed phrases, private keys, or passwords
Protecting diary entries or private notes stored in cloud sync services
Learning or demonstrating how AES-GCM and PBKDF2 work in practice

What this tool is not for

File encryption at scale — for files, use VeraCrypt, 7-Zip AES, or GPG.
End-to-end messaging — Signal, WhatsApp, and iMessage provide this with key exchange built in. Manual AES requires a pre-shared password.
Long-term archival — cryptographic standards evolve. Review your encryption scheme periodically.

Related tools and guides

Hash Generator — SHA-256, SHA-512, MD5 hashes computed in the browser
Password Generator — generate strong passwords to use with this tool
Base64 Encoder/Decoder — encode and decode base64 strings
How to generate a hash without uploading

Frequently Asked Questions

What algorithm does browser-based text encryption use?: AES-256-GCM (Galois/Counter Mode) with PBKDF2 key derivation (SHA-256, 100,000 iterations). A random 16-byte salt and 12-byte IV are generated per encryption. This is the same cipher used in TLS 1.3, Signal, and modern password managers.
Is client-side encryption actually secure?: Yes — the cryptographic strength of AES-256-GCM is not weakened by running it in a browser. The key is derived from your password locally via the browser's SubtleCrypto API. Security depends on password strength; weak passwords produce weak encryption regardless of the cipher.
How is client-side encryption different from encryption-as-a-service?: An encryption service receives your plaintext on a server, encrypts it, and returns the ciphertext — you must trust the operator not to log your data. A browser-based tool performs all cryptographic operations locally; the server never sees your plaintext or password.
Can I decrypt this with another tool?: Yes. The output format is base64(salt[16] + IV[12] + AES-256-GCM ciphertext). Any implementation using AES-256-GCM + PBKDF2 (SHA-256, 100k iterations) with the same parameter layout can decrypt it.