PGP Digital Timestamping Service webpage mentions

The service operates in a number of different "modes" depending upon the required results. The current modes are:-

post: forwarding an outbound message with a proof of posting certificate
clear: the received message is clearsigned and returned to the sender
header: the received message (with headers) is clearsigned and returned to the sender
text: the received message is signed and returned ASCII armoured to the sender
pgp: the received message (which must be ASCII armoured) is assumed to be a PGP file which is then signed and returned to the sender
binary: the received message (which must be ASCII armoured) is assumed not to be a PGP file which is then signed and returned to the sender

What is a clearsigned message? I searched around quite a bit using Duck Duck Go, and on this site but I couldn't find an explanation.


From dictionary.university with search clearsigned definition

  1. Dictionary of Internet Terms A digitally signed S/MIME or PGP message in which the content of the message is readable even if the signature is not.
  1. A message that is digitally signed but not encrypted.

These might be helpful, too;

  • Cleartext is readable data transmitted or stored “in the clear” (i.e. unencrypted)

  • Plaintext is the input to an encryption algorithm

  • Ciphertext is the unreadable output of an encryption algorithm

  • Plain text means its text that hasn’t been formatted (i.e., a plain text file)

    Note that plain text might be an ambiguous term without context. See the commnets.

  • 1
    $\begingroup$ "Plain Text" is ambiguous. It might be US ASCII. It might be Unicode in UTF-8. It might be Unicode in UCS-2 (Microsoft Windows). It might be ISO/IEC 8859-1:1998 Latin-1. It's probably Unicode these days, most commonly UTF-8. But the old formats still exist, and can be problematic when someone in the US wants "plain text" meaning US English without accents and rejects text in other languages. $\endgroup$ May 27 at 12:49
  • $\begingroup$ @SAIPeregrinus It is more about higher level, In computing, plain text is a loose term for data (e.g. file contents) that represent only characters of readable material but not its graphical representation nor other objects (floating-point numbers, images, etc.). $\endgroup$
    – kelalaka
    May 27 at 14:50
  • $\begingroup$ Yep, but people confuse the (many) uses op the term. EG emoji are "Plain Text" to Unicode, despite being displayed as images to the user. Egyptian heiroglyphs like 𓃤 are plain text. Playing cards like 🂼 are plain text. The "Control Pictures" plane is a set of pictures, but still text. You can use Unicode to write "rich text" English like 𝗯𝗼𝗹𝗱 or 𝘪𝘵𝘢𝘭𝘪𝘤 in "plain text". Etc. Even in ASCII the non-printable control characters are "plain text" despite not being human-readable. It's an ambiguous term, the meaning depends on the encoding. $\endgroup$ May 27 at 15:07
  • $\begingroup$ It really depends on the context, I've put it since there is a distinction between plain text and plaintext. Usually, the compound word later combined in English ( at least American English). Like on-line now online. In this case, the meaning a bit different, that was my point. If you really consider that is confusing, I can simply delete it. $\endgroup$
    – kelalaka
    May 27 at 15:11
  • 1
    $\begingroup$ I don't think that part is confusing. "Plaintext“ is a well-defined term, though it doesn't have anything to do with text. "Plain Text" is not well-defined or even fully definable. A bit like "char" being a C type of at least 8 bits, vs "character" being an ambiguous element of some written communication system. It's worth making the distinction, and worth warning people against using the ambiguous terms. $\endgroup$ May 27 at 15:26

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