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Books / Practical Cryptography for Developers (Unfinished) / Chapter 4
Exercises - Pseudo-Random Generator
Write a code to generate 30 pseudo-random integers in the range [1…10], starting from certain entropy, taken as input, using HMAC key derivation.
From the entropy generate a seed (256-bit binary sequence) using SHA-256:
seed = SHA256(entropy)
Generate the n-th random number by the formula:
1 + HMAC-SHA256(n, seed) % 10
Print the numbers at the output, separated by space.
Sample input and corresponding output:
| Input | Output |
|---|---|
| hello | 8 4 10 5 5 3 5 7 10 6 4 9 2 3 2 8 3 3 10 6 8 10 9 10 1 3 6 4 4 10 |
| random text | 10 5 5 9 7 4 2 9 2 1 10 4 8 9 8 1 8 6 5 7 5 4 3 4 6 6 9 8 1 1 |
| fun | 6 5 9 2 2 5 1 6 10 10 10 1 8 10 6 9 2 1 5 10 1 4 8 5 6 3 8 4 2 1 |