add a new API to allow user to upload an existing certificate

is needed to be able to setup sharing when an user has an existing
certificate that may have been created outside of Nextcloud end-to-end
encryption app

that would for example apply when an external certificate authority is
in use to deliver user certificates for end-to-end encryption

Signed-off-by: Matthieu Gallien <matthieu.gallien@nextcloud.com>

appinfo/routes.php

@@ -30,6 +30,7 @@
 		['name' => 'Key#setPrivateKey', 'url' => '/api/v{apiVersion}/private-key', 'verb' => 'POST', 'requirements' => ['apiVersion' => '[1-2]']],
 		['name' => 'Key#getPrivateKey', 'url' => '/api/v{apiVersion}/private-key', 'verb' => 'GET', 'requirements' => ['apiVersion' => '[1-2]']],
 		['name' => 'Key#deletePrivateKey', 'url' => '/api/v{apiVersion}/private-key', 'verb' => 'DELETE', 'requirements' => ['apiVersion' => '[1-2]']],
+		['name' => 'Key#setPublicKey', 'url' => '/api/v{apiVersion}/public-key', 'verb' => 'PUT', 'requirements' => ['apiVersion' => '[1-2]']],
 		['name' => 'Key#createPublicKey', 'url' => '/api/v{apiVersion}/public-key', 'verb' => 'POST', 'requirements' => ['apiVersion' => '[1-2]']],
 		['name' => 'Key#getPublicKeys', 'url' => '/api/v{apiVersion}/public-key', 'verb' => 'GET', 'requirements' => ['apiVersion' => '[1-2]']],
 		['name' => 'Key#deletePublicKey', 'url' => '/api/v{apiVersion}/public-key', 'verb' => 'DELETE', 'requirements' => ['apiVersion' => '[1-2]']],

lib/Controller/KeyController.php

@@ -205,6 +205,26 @@ public function createPublicKey(string $csr): DataResponse {
 		return new DataResponse(['public-key' => $publicKey]);
 	}
 
+	/**
+	 * Set public key
+	 *
+	 * @NoAdminRequired
+	 * @E2ERestrictUserAgent
+	 * @throws OCSBadRequestException
+	 */
+	public function setPublicKey(string $publicKey): DataResponse {
+		try {
+			$this->keyStorage->setPublicKey($publicKey, $this->userId);
+		} catch (KeyExistsException $e) {
+			return new DataResponse([], Http::STATUS_CONFLICT);
+		} catch (Exception $e) {
+			$this->logger->error("Fail to set user public key", ['exception' => $e, 'app' => $this->appName]);
+			throw new OCSBadRequestException($this->l10n->t('Internal error'));
+		}
+
+		return new DataResponse(['public-key' => $publicKey]);
+	}
+
 	/**
 	 * Delete the users public key
 	 *