* With 'md5' option, the whole file is hashed through md5. This is the default.
* With 'md5_outside', hash is computed using:
* - md5 of the first part of the file,
* With 'md5' option, the whole file is hashed through md5. This is the default.
* With 'md5_outside', hash is computed using:
* - md5 of the first part of the file,