In a nutshell:
Intel® Secure Key, was previously code-named Bull Mountain Technology. It is the Intel name for the Intel® 64 and IA-32 Architectures instruction RDRAND and its underlying Digital Random Number Generator (DRNG) hardware implementation. Among other things, the DRNG using the RDRAND instruction is useful for generating high-quality keys for cryptographic protocols.
The Bull Mountain Software Implementation Guide has been renamed: (here is a brief summary of the guide)
The Digital Random Number Generator Software Implementation Guide is intended to provide a complete source of technical information on RDRAND usage, including code examples. Included in this document are the following additional sections:
Section 2 of the Guide contains the following information: Random Number Generator (RNG) Basics and Introduction to the DRNG. This section describes the nature of an RNG and its pseudo- (PRNG) and true- (TRNG) implementation variants, including modern cascade construction RNGs. We then present the DRNG's position within this broader taxonomy.
Section 3 provides a DRNG Overview. In this section, we provide a technical overview of the DRNG, including its component architecture, robustness features, manner of access, performance, and power requirements.
Section 4 shows RDRAND Instruction Usage. This section provides reference information on the RDRAND instruction and code examples showing its use. This includes RDRAND platform support verification and suggestions on DRNG-based libraries.
The document is designed to serve a variety of readers. Programmers who already understand the nature of RNGs may refer directly to section 4 for RDRAND instruction reference and code examples. RNG newcomers who need some review of concepts to understand the nature and significance of the DRNG can refer to section 2. Nearly all users will want to look at section 3 which provides a technical overview of the DRNG.