The following sentence appears in an article in the web:

All cryptographic metadata is stored in the headers of files, so encrypted data can be easily moved, stored for backup and recovered.

That files have headers is news for me. Are these name/value pairs like environment variables or HTTP headers? Are they freely editable/customizable? How can I see the headers of any file in my filesystem?

Examples would be appreciated.

  • 3
    There is no standardised definition of file headers. The article in question is probably highlighting the fact that the metadata is stored in the encrypted files rather than alongside them, so each file's metadata stays with it even when it is moved or copied. – Stephen Kitt May 13 '16 at 22:22
  • Do you mean that the encrypted version of the plain text file acts, in this regard, as a wrapper of the latter, by first encrypting the file and then prepending headers to it? – ARX May 13 '16 at 22:40
  • it seems your question is a context specific: it is related to the eCryptfs way to store information that is necessary to decrypt a file in a header it keeps in the beginning of a regular file used as a backing up storage for encrypted file. Read the first paragraph of the 'Basics' in the article you referred. – Serge May 13 '16 at 22:55
  • @Serge: The quoted sentence comes from the first paragraph of the 'Basics' section. And you are right. The question is eCryptfs-specific. But that the headers were eCryptfs-specific was not obvious from the article (that confused me). Now that's clear from Stephen Kitt's comment. If I follow you well, you confirm my new understanding: the encrypted file wraps eCryptfs-specific headers along with the cipher text version of the original file. – ARX May 13 '16 at 23:31
  • Yes, I meant exactly this. – Serge May 13 '16 at 23:37

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