  The number of public and private web archives has increased, and we
implicitly trust content delivered by these archives. Fixity is checked to
ensure an archived resource has remained unaltered since the time it was
captured. Some web archives do not allow users to access fixity information
and, more importantly, even if fixity information is available, it is provided
by the same archive from which the archived resources are requested. In this
research, we propose two approaches, namely Atomic and Block, to establish and
check fixity of archived resources. In the Atomic approach, the fixity
information of each archived web page is stored in a JSON file (or a manifest),
and published in a well-known web location (an Archival Fixity server) before
it is disseminated to several on-demand web archives. In the Block approach, we
first batch together fixity information of multiple archived pages in a single
binary-searchable file (or a block) before it is published and disseminated to
archives. In both approaches, the fixity information is not obtained directly
from archives. Instead, we compute the fixity information (e.g., hash values)
based on the playback of archived resources. One advantage of the Atomic
approach is the ability to verify fixity of archived pages even with the
absence of the Archival Fixity server. The Block approach requires pushing
fewer resources into archives, and it performs fixity verification faster than
the Atomic approach. On average, it takes about 1.25X, 4X, and 36X longer to
disseminate a manifest to perma.cc, archive.org, and webcitation.org,
respectively, than archive.is, while it takes 3.5X longer to disseminate a
block to archive.org than perma.cc. The Block approach performs 4.46X faster
than the Atomic approach on verifying the fixity of archived pages.
