Abstract: Secure hashing of large files to verify file identity. In some implementations, a method includes determining a size of a particular file received by an endpoint device, and searching for a record indexed in a data structure based on the size. In response to finding the record, a sequence of multiple records is accessed in the data structure. For each record of the sequence, a particular data portion is hashed that has a location in the particular file that corresponds to a location in the record to obtain a particular hash result. In response to the particular hash result matching a corresponding previous hash result stored in the record based on an associated data portion in an associated file, the particular file is determined to be the same as the associated file, and characteristics of the particular file are determined using file information for the associated file.