openpgp-notes/book/source/13-armor.md

<!--
SPDX-FileCopyrightText: 2023 The "Notes on OpenPGP" project
SPDX-License-Identifier: CC-BY-SA-4.0
-->

# ASCII Armor

The native format of OpenPGP data is binary.

However, in many use cases it is customary to use OpenPGP data in a non-binary encoding called "ASCII Armor." For example, ASCII Armored OpenPGP data is often used in email, for encrypted messages or for signatures.

OpenPGP's ASCII Armor mechanism consists of:

- A [header line](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-header-line)
- [Headers](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-headers) that can contain additional metadata
- The [Base64 encoded](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-base64-conversions) OpenPGP data
  - An optional checksum for this data
- A ["tail line"](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-tail-line) (footer) that matches the header line

## The Cleartext Signature Framework

```{admonition} TODO
:class: warning

Explain/discuss, [link](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-cleartext-signature-framewo)

  - Linebreak normalization?
  - Dash escaping
```


## Advanced topics

### CRC (and its deprecation in crypto-refresh)

See https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-optional-checksum
feat: Add license attribution for all files Signed-off-by: David Runge <dave@sleepmap.de> 2023-10-23 19:04:58 +02:00			`<!--`
			`SPDX-FileCopyrightText: 2023 The "Notes on OpenPGP" project`
			`SPDX-License-Identifier: CC-BY-SA-4.0`
			`-->`

Initial outline and old notes (Rough merge of two precursor projects by Heiko, and outline notes by Paul) 2023-09-14 21:30:43 +02:00			`# ASCII Armor`

armor: add some content and outline 2023-09-26 12:56:56 +02:00			`The native format of OpenPGP data is binary.`

			`However, in many use cases it is customary to use OpenPGP data in a non-binary encoding called "ASCII Armor." For example, ASCII Armored OpenPGP data is often used in email, for encrypted messages or for signatures.`

			`OpenPGP's ASCII Armor mechanism consists of:`

			`- A [header line](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-header-line)`
			`- [Headers](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-headers) that can contain additional metadata`
			`- The [Base64 encoded](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-base64-conversions) OpenPGP data`
			`- An optional checksum for this data`
			`- A ["tail line"](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-armor-tail-line) (footer) that matches the header line`

			`## The Cleartext Signature Framework`

			```{admonition} TODO
			`:class: warning`

			`Explain/discuss, [link](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-cleartext-signature-framewo)`

ch11: add note 2023-09-21 11:36:43 +02:00			`- Linebreak normalization?`
armor: add some content and outline 2023-09-26 12:56:56 +02:00			`- Dash escaping`
			```


			`## Advanced topics`

			`### CRC (and its deprecation in crypto-refresh)`

			`See https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-10.html#name-optional-checksum`