Expanded minimum RSA Keylength to 3072

German Federal Office for Information Security requests in its technical guideline BSI TR-02102-1 RSA Keylength not shorter than 3000bits starting 2024, in the year 2023 3000bits as a recommendation. Gitea should request longer RSA Keys by default in favor of security and drop old clients which do not support shorter keys.

Author: mainboarder

custom/conf/app.example.ini

@@ -1339,7 +1339,7 @@ LEVEL = Info
 ;; Define allowed algorithms and their minimum key length (use -1 to disable a type)
 ;ED25519 = 256
 ;ECDSA = 256
-;RSA = 2047 ; we allow 2047 here because an otherwise valid 2048 bit RSA key can be reported as having 2047 bit length
+;RSA = 3071 ; we allow 3071 here because an otherwise valid 3072 bit RSA key can be reported as having 3071 bit length
 ;DSA = -1 ; set to 1024 to switch on
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

docs/content/administration/config-cheat-sheet.en-us.md

@@ -681,7 +681,7 @@ Define allowed algorithms and their minimum key length (use -1 to disable a type
 
 - `ED25519`: **256**
 - `ECDSA`: **256**
-- `RSA`: **2047**: We set 2047 here because an otherwise valid 2048 RSA key can be reported as 2047 length.
+- `RSA`: **3071**: We set 3071 here because an otherwise valid 3072 RSA key can be reported as 3071 length.
 - `DSA`: **-1**: DSA is now disabled by default. Set to **1024** to re-enable but ensure you may need to reconfigure your SSHD provider
 
 ## Webhook (`webhook`)

docs/content/administration/config-cheat-sheet.zh-cn.md

@@ -648,7 +648,7 @@ Gitea 创建以下非唯一队列：
 
 - `ED25519`：**256**
 - `ECDSA`：**256**
-- `RSA`：**2047**：我们在这里设置为2047，因为一个其他方面有效的2048 RSA密钥可能被报告为2047长度。
+- `RSA`：**3071**：我们在这里设置为2047，因为一个其他方面有效的3072 RSA密钥可能被报告为3071长度。
 - `DSA`：**-1**：默认情况下禁用DSA。设置为**1024**以重新启用，但请注意可能需要重新配置您的SSHD提供者
 
 ## Webhook (`webhook`)

modules/setting/ssh.go

@@ -60,7 +60,7 @@ var SSH = struct {
 	ServerMACs:                    []string{"[email protected]", "hmac-sha2-256", "hmac-sha1"},
 	KeygenPath:                    "",
 	MinimumKeySizeCheck:           true,
-	MinimumKeySizes:               map[string]int{"ed25519": 256, "ed25519-sk": 256, "ecdsa": 256, "ecdsa-sk": 256, "rsa": 2047},
+	MinimumKeySizes:               map[string]int{"ed25519": 256, "ed25519-sk": 256, "ecdsa": 256, "ecdsa-sk": 256, "rsa": 3071},
 	ServerHostKeys:                []string{"ssh/gitea.rsa", "ssh/gogs.rsa"},
 	AuthorizedKeysCommandTemplate: "{{.AppPath}} --config={{.CustomConf}} serv key-{{.Key.ID}}",
 	PerWriteTimeout:               PerWriteTimeout,