Google Keep Encryptor
> SJCL is secure. It uses the industry-standard AES algorithm at 128, 192 or 256 bits; the SHA256 hash function; the HMAC authentication code; the PBKDF2 password strengthener; and the CCM and OCB authenticated-encryption modes. Just as importantly, the default parameters are sensible: SJCL strengthens your passwords by a factor of 1000 and salts them to protect against rainbow tables, and it authenticates every message it sends to prevent it from being modified.
**WARNING: If you don't remember the password, you will lose all the information on that encrypted note!!!** It's strongly recommended to use password hints as labels or add them to the title of your encrypted notes.