Fidelity.com

Fidelity's Commitment to Electronic Security
To provide a high degree of confidentiality and security for your personal financial information, this online application uses either 40-bit or 128-bit encryption, depending on the level of encryption available in your Internet browser. Encryption is the process of scrambling your trading and account information as it passes between Fidelity and your computer. The larger the number of bits for encryption (e.g., 40 or 128) the more difficult (exponentially) it is for an unauthorized person to unscramble the transmission.

Fidelity.com also incorporates a variety of other electronic security measures:

Requiring users to enter a password and Social Security number or username.
Extensive use of firewall barriers
24-hour monitoring of access to Fidelity data and information