Sorry to barge in from the outside, but your question is vaguely specified. > Out of curiosity, were Speck to be known as vulnerable to key recovery attacks, w

Sorry to barge in from the outside, but your question is vaguely specified. > Out of curiosity, were Speck to be known as vulnerable to key recovery attacks, would you still endorse it as better than no encryption? My answer to this would be: "it depends". In this case, it depends on the security margin and just how much easier the key recovery attacks would be compared to brute force. For a cipher with 128-bit key, if the best known attack, after years of careful and aggressive cryptanalysis, required 2^122 work I probably would use it. If the best attack required 2^90 work, I wouldn't use it. After all we are talking about security margins and risk tolerance.