I can assure you, on my reputation, that all client data has been encrypted and will never be leaked.

"I can assure you (that)" 是固定表达，用于加强承诺或保证的可信度，can 在此强调说话人的诚意和确定性，而非能力。常出现在正式或严肃的语境中，表示说话人对所述内容完全负责。