Digital Signatures and Certificates

When we think of VPNs, often our first thought is that of encryption of the user data. But adversaries or those intent on reading the data could However an attacker could record a conversation and then replay the replies between to participants. What we need to do is to be able to ensure the source of the data is genuine, and that is where digital signatures and certificates comes in.

To construct a Digital Signature, public key encryption systems must be in place. The construction of the Digital Signature entails applying a hash function to the message by concatenation of the message with a known secret key and then applying a mathematical function which will produce a fixed length output known as the digest. The digest is then encrypted with the public decryption key which produces a signature that can be appended to the message to verify that the message is from the genuine source.

The receiver recalculates the hash function and compared with the signature after applying the public key. If the two match, then because only the originator could have known the hash function and the private key, the message must be genuine.

Message Digest algorithms use Hash functions to map many potential inputs to each of a large number of outputs. What is normally produced is a fixed length field, typically a few hundred bits in length. A secret key is shared between sender and receiver and by concatenating this with a message for transfer, the digest

Read More

Science & Technology

The content standards presented in this chapter outline what students should know, understand, and be able to do in natural science. The content standards are a complete set of outcomes for students; they do not prescribe a curriculum. These standards were designed and developed as one component of the comprehensive vision of science education presented in the National Science Education Standards and will be most effective when used in conjunction with all of the standards described in this book. Furthermore, implementation of the content standards cannot be successful if only a subset of the content standards is used (such as implementing only the subject matter standards for physical, life, and earth science).

Technology in the hands of businessmen

The eight categories of content standards are:

  • Unifying concepts and processes in science.
  • Science as inquiry.
  • Physical science.
  • Life science.
  • Earth and space science.
  • Science and technology.
  • Science in personal and social perspectives.
  • History and nature of science.

The standard for unifying concepts and processes is presented for grades K-12, because the understanding and abilities associated with major conceptual and procedural schemes need to be developed over an entire education, and the unifying concepts and processes transcend disciplinary boundaries. The next seven categories are clustered for grades K-4, 5-8, and 9-12. Those clusters were selected based on a combination of factors, including cognitive development theory, the classroom experience of teachers, organization of schools, and the frameworks of other disciplinary-based standards. References for additional reading for all the content standards are presented at

Read More

The Concept Phase in Agile Product Development

Four phases to deliver value on Agile projects
Concept phase – which is where we outline the goals, outcomes and justification for the initiative.

  • Initiate phase – where we identify the foundations of the solution, build an initial prioritized backlog and a good enough initial release plan.
  • Delivery phase – which involves creating functionality from the requirements through design, analysis, testing, build and deployment. The deliver cycle is repeated until the project ends.
  • Closure phase – where we take the lessons learned on this initiative and amplify them to the whole organisation, deliver the business benefits and alleviate the people so they can join other projects.
  • Learn and adapt is not listed as a phase as it should be an activity that is continuous in nature.

Why the need for a concept phase?
Scrum focuses on the delivery of (software) projects. Naturally it doesn’t take into account phases leading up to the point where we start building the requirements. In this article we briefly look at the phases that prepare value- and delivery teams for building and delivering software.

Concept phase
The input to the concept phase deals with a new idea or need for change. A journey of discovery into what it is that the potential idea or product can do for our business embarks. The discoveries here are translated into desired outcomes. These are typically our acceptance criteria for the project.

Project stakeholders
The concept phase is our opportunity to identify all the stakeholders that may be impacted

Read More