Update quickstart document

docs/source/pgpainless-sop/quickstart.md

@@ -75,10 +75,21 @@ In both cases, the resulting output will be the UTF8 encoded, ASCII armored Open
 
 To disable ASCII armoring, call `noArmor()` before calling `generate()`.
 
-At the time of writing, the resulting OpenPGP secret key will consist of a certification-capable 256-bits
+Revision `05` of the Stateless OpenPGP Protocol specification introduced the concept of profiles for
+certain operations.
+The key generation feature is the first operation to make use of profiles to specify different key algorithms.
+To set a profile, simply call `profile(String profileName)` and pass in one of the available profile identifiers.
+
+To explore, which profiles are available, refer to the dedicated [section](#explore-profiles).
+
+The default profile used by `pgpainless-sop` is called `draft-koch-eddsa-for-openpgp-00`.
+If this profile is used, the resulting OpenPGP secret key will consist of a certification-capable 256-bits
 ed25519 EdDSA primary key, a 256-bits ed25519 EdDSA subkey used for signing, as well as a 256-bits X25519
 ECDH subkey for encryption.
 
+Another profile defined by `pgpainless-sop` is `rfc4880`, which changes the key generation behaviour such that
+the resulting key is a single 4096-bit RSA key capable of certifying, signing and encrypting.
+
 The whole key does not have an expiration date set.
 
 ### Extract a Certificate
@@ -186,6 +197,13 @@ If any keys used for signing are password protected, you need to provide the sig
 It does not matter in which order signing keys and key passwords are provided, the implementation will figure out
 matches on its own. If different key passwords are used, the `withKeyPassword(_)` method can be called multiple times.
 
+You can modify the behaviour of the encrypt operation by switching between different profiles via the
+`profile(String profileName)` method.
+At the time of writing, the only available profile for this operation is `rfc4880` which applies encryption
+as defined in [rfc4880](https://datatracker.ietf.org/doc/html/rfc4880).
+
+To explore, which profiles are available, refer to the dedicated [section](#explore-profiles).
+
 By default, the encrypted message will be ASCII armored. To disable ASCII armor, call `noArmor()` before the
 `plaintext(_)` method call.
 
@@ -464,3 +482,23 @@ By default, the signatures output will be ASCII armored. This can be disabled by
 prior to `message(_)`.
 
 The detached signatures can now be verified like in the section above.
+
+### Explore Profiles
+
+Certain operations allow modification of their behaviour by selecting between different profiles.
+An example for this is the `generateKey()` operation, where different profiles result in different algorithms used
+during key generation.
+
+To explore, which profiles are supported by a certain operation, you can use the `listProfiles()` operation.
+For example, this is how you can get a list of profiles supported by the `generateKey()` operation:
+
+```java
+List<Profile> profiles = sop.listProfiles().subcommand("generate-key");
+```
+
+:::{note}
+As you can see, the argument passed into the `subcommand()` method must match the operation name as defined in the
+[Stateless OpenPGP Protocol specification](https://datatracker.ietf.org/doc/draft-dkg-openpgp-stateless-cli/).
+:::
+
+At the time of writing (the latest revision of the SOP spec is 06), only `generate-key` and `encrypt` accept profiles.