Personal Privacy Speech Encryption Device

I am seeking an expert to develop a speech encryption device dedicated to protecting personal privacy. The device should primarily run on bespoke hardware.

The key feature needed is:
- Manual encryption capabilities.

There is no need for voice recognition or automatic encryption features in this project. The candidate with substantial experience in hardware-based encryption methods will be a good fit for this job. Understanding the sensitivity of personal conversations and expertise in creating user-friendly manual encryption solutions will be a major plus.