Software Installation Package With Digital Signatures

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, create and use software installation packages including digital signatures. In one aspect, a method includes obtaining a first installation package including program content and package information, which includes information stored in a platform independent format and useable in an installation sequence; converting the first installation package into a second installation package stored in a format native to a target platform, the second installation package including at least a portion of the program content and the information useable in the installation sequence, and the converting includes identifying a digital signature native to the target platform and combining the digital signature native to the target platform with a document native to the target platform, the document including at least a portion of the program content; and initiating installation on the target platform with the second, native installation package.