K3 Key variants
Needs: Supporter
Binding a key to its use by XOR with a variant constant, and why key blocks replaced variants.
This is a supporter feature. Create a free account, then try every supporter feature free for 7 days.
What this module covers
You will be able to
- Apply and recognise a variant
- Explain how variants bind usage
- Explain why key blocks replaced them
The lesson
- Why it matters
- The concept
- Step by step
- Why key blocks replaced variants
- Common mistakes
- What to test
In the module
- The lesson, with diagrams, common mistakes and what to test
- A worked example you can change: Applying an Atalla variant
- Practice: 2 kinds of generated exercise, each with a step-by-step solution
- A quiz of 9 questions
Key terms
- Atalla variant
- The Atalla HSM convention: a variant number from 0 to 31, multiplied by 8, is XORed into the first byte of each 8-byte part of the key, giving each key type its own variant.
- Control vector
- IBM's way to bind a key's usage to the key: a structured value XORed into the key-encrypting key before it wraps the key.
- Key variant
- A key changed by XORing a constant into some bytes, so that one key gives several different keys, one per purpose.
- Variant mask
- The constant XORed into a key to make a variant, such as the DUKPT PIN variant 00000000000000FF00000000000000FF.
The lesson, worked example, practice and quiz open with a supporter pass, which you can try free for 7 days.