Editing DOCSIS (section)

== Security ==
DOCSIS includes [[media access control]] (MAC) layer security services in its Baseline Privacy Interface specifications. DOCSIS 1.0 used the initial Baseline Privacy Interface (BPI) specification. BPI was later improved with the release of the Baseline Privacy Interface Plus (BPI+) specification used by DOCSIS 1.1 and 2.0. Most recently, a number of enhancements to the Baseline Privacy Interface were added as part of DOCSIS 3.0, and the specification was renamed "Security" (SEC).

The intent of the BPI/SEC specifications is to describe MAC layer security services for DOCSIS CMTS to cable modem communications. BPI/SEC security goals are twofold:
* Provide cable modem users with [[data privacy]] across the cable network
* Provide cable service operators with service protection (i.e. prevent unauthorized modems and users from gaining access to the network's RF MAC services)

BPI/SEC is intended to prevent cable users from listening to each other. It does this by [[Encryption|encrypting]] data flows between the CMTS and the cable modem. BPI and BPI+ use 56-bit [[Data Encryption Standard]] (DES) encryption, while SEC adds support for 128-bit [[Advanced Encryption Standard]] (AES). The AES key, however, is protected only by a 1024-bit RSA key.<ref>{{cite tech report |title=Data-Over-Cable Service Interface Specifications DOCSIS 3.0 Security Specification |url=https://community.cablelabs.com/wiki/plugins/servlet/cablelabs/alfresco/download?id=2bdb7994-798c-4b65-a5bd-a92c9da7e72c |format=PDF |institution=CableLabs |date=2006–2013 |page=87 |number=CM-SP-SECv3.0-I15-130808 }}</ref>

BPI/SEC is intended to allow cable service operators to refuse service to uncertified cable modems and unauthorized users. BPI+ strengthened service protection by adding [[digital certificate]] based authentication to its [[key exchange]] protocol, using a [[public key infrastructure]] (PKI), based on digital [[Certificate authority|certificate authorities]] (CAs) of the certification testers, currently Excentis (formerly known as tComLabs) for EuroDOCSIS and CableLabs for DOCSIS. Typically, the cable service operator manually adds the cable modem's [[MAC address]] to a customer's account with the cable service operator;<ref>{{cite magazine |title=United States v. Ryan Harris a.k.a. DerEngel and TCNISO, Inc. |page=2 |url=https://www.wired.com/images_blogs/threatlevel/2009/11/derengel_indictment1.pdf | quote=When a computer user seeks to access the internet, the user's modem will report its MAC address to the ISP, and if the ISP recognizes the modem's MAC address as belonging to a paying subscriber, the ISP will allow the user to access the internet via the ISP's network. |magazine=Wired }}</ref> and the network allows access only to a cable modem that can attest to that MAC address using a valid certificate issued via the PKI. The earlier BPI specification (ANSI/SCTE {{Not a typo|22-2}}) had limited service protection because the underlying [[key management]] protocol did not [[Authentication|authenticate]] the user's cable modem.

Security in the DOCSIS network is vastly improved when only business critical communications are permitted, and end user communication to the network infrastructure is denied. Successful attacks often occur when the CMTS is configured for backward compatibility with early pre-standard DOCSIS 1.1 modems. These modems were "software upgradeable in the field", but did not include valid DOCSIS or EuroDOCSIS root certificates.{{Citation needed|date=April 2023}}