A method and mechanism for protecting a website against defacement are provided. A content owner may associate content with a digital signature. The digital signature allows a recipient of the content to verify that the content originated from the content owner, and that the content has not been defaced. The digital signature may be comprised within the content, or stored external to the content, e.g., in a repository accessible to a Web cache server serving the content. To construct the digital signature, initially, the content owner creates a content validity value for a portion of content, the content validity value is encrypted to create the digital signature. The Web cache server may use the digital signature to determine whether the content has been defaced.