openpgp-notes/book/source/13-armor.md
2023-09-26 12:56:56 +02:00

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# 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