Abstract: An archive of an object set may include various security features that enable a detection of alterations of the contents of the objects. However, the security measures of an archive may fail to detect an inadvertent or intentional alteration of the structure of the object set, including the addition of new objects, changes to the metadata (e.g., the name, position within the object set, and location and size within the archive) of respective objects of the object set, and the deletion of directory entries for the objects. Therefore, an archive may be generated with verifiers (e.g., hashcodes) calculated not only for the contents of objects, but for the directory of the archive, and may be included in the signature of the archive. This verification may extend the detecting of alteration of the archive to include the structure of the archive as well as the contents of the objects contained therein.

Abstract: The objects of an archive may be verified with a cryptographic signature stored in the archive. However, when an object is extracted, the authentication involves re-authenticating the entire archive, re-extracting the object, and comparing the extracted object with the current object, which is inefficient or unachievable if the archive is unavailable. Instead, the archive may include a block map signed with the signature and comprising hashcodes for respective blocks of the objects of the archive. When an object is extracted, the signature and block map may also be extracted and stored as objects outside of the archive. The extracted signature and block map may later be verified by authenticating the signature, verifying the block map with the signature, and matching the hashcodes of the block map with those of the blocks of the extracted objects, thus enabling a more efficient and portable verification of extracted object with extracted authentication credentials.

Abstract: Objects of an object set stored in an archive may be randomly accessed using the addresses of the objects stored in the archive. However, archives often fail to enable random access to the data within an object, without accessing other portions of the object, due to the variable compression of respective segments of the object. Random-access capabilities within the objects may be provided by segmenting the object into segments of a segment size, generating a block map specifying the block sizes of respective blocks corresponding to respective segments of the objects, and storing the block map in the archive as an object of the object set. Additionally, hashcodes may be calculated respective blocks and included in the block map in order to expose alterations of respective blocks, and/or to update an archive to an updated version of the archive by comparing the hashcodes and retrieving and substituting the updated blocks.

Abstract: The objects of an archive may be verified with a cryptographic signature stored in the archive. However, when an object is extracted, the authentication involves re-authenticating the entire archive, re-extracting the object, and comparing the extracted object with the current object, which is inefficient or unachievable if the archive is unavailable. Instead, the archive may include a block map signed with the signature and comprising hashcodes for respective blocks of the objects of the archive. When an object is extracted, the signature and block map may also be extracted and stored as objects outside of the archive. The extracted signature and block map may later be verified by authenticating the signature, verifying the block map with the signature, and matching the hashcodes of the block map with those of the blocks of the extracted objects, thus enabling a more efficient and portable verification of extracted object with extracted authentication credentials.

Abstract: An archive of an object set may include various security features that enable a detection of alterations of the contents of the objects. However, the security measures of an archive may fail to detect an inadvertent or intentional alteration of the structure of the object set, including the addition of new objects, changes to the metadata (e.g., the name, position within the object set, and location and size within the archive) of respective objects of the object set, and the deletion of directory entries for the objects. Therefore, an archive may be generated with verifiers (e.g., hashcodes) calculated not only for the contents of objects, but for the directory of the archive, and may be included in the signature of the archive. This verification may extend the detecting of alteration of the archive to include the structure of the archive as well as the contents of the objects contained therein.