SSH Communications Security Software Developer interview questions

Had a friendly initial introductory interview, then a technical interview on location. The questions were overall manageable and the people involved were friendly and patient. I, unfortunately, failed to properly answer a few of the more indepth questions. The only minus point was that the interviewers mentioned they either give an assignment or look at my github, but when I asked if I could do the assignment as I do not have a public repository relevant to the position, I got denied. Then, later, one of the reasons I got rejected in the final shortlist was due to not having work relevant to the position on my public profile. Aside from that, the process felt fair and reasonable.

I applied with an HR. After the first screen call I got a list of questions about my work experience on e-mail. The second call was from a manager at SSH. He sounded grim and unwilling to talk. We talked mainly about security, TLS, PKC, and he assured me that just basic knowledge of security is needed in this position (which I do posess). He told me to do the coding assingment. After I did the coding assingment and waited more that a week for the feedback, I got an email with these words: "the coding task is ok, but you lack the security knowledge, so rejected". I am still confused, why they decided what I lack and what I don't, since no evaluation of my skills was performed and I was told that no strong security skills were needed at this position. So, for me it was a huge waste of hope and time.