A credibility based logo contains a symbol and a name. Both describe the business you are in. A describing name supports the symbology and makes it more memorable.
Additionally, the lock, even without the chain, already contains "protection". Less is more and more memorable.
Good luck!

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Assistant to Bill Haig. For a complete Credibility Based Logo Design sm review visit http://www.powerlogos.com and access Bill Haigs no cost logo evaluation form on the home page.