Method, apparatus, computer programs and data structures are provided, according to at least one embodiment, wherein an author of digital content identifies at least some trusted code that the author trusts to be used to read digital content, and stores information in the unit of digital content that is capable of identifying the trusted code. In at least some embodiments, the unit of digital content is an electronic document. In other embodiments, a publisher of the trusted code, or an author of the digital content, signs the trusted code with a private key, and a certificate associated with the private key is embedded in the unit of digital content. The certificate may provide public key information associated with the private key. The public key may be used to verify that code is trusted before it is allowed access to the unit of digital content.
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