added support for PPK format private keys

Cargo.toml

@@ -27,7 +27,7 @@ sha1 = { version = "0.10.5", features = ["oid"] }
 sha2 = { version = "0.10.6", features = ["oid"] }
 signature = "2.2"
 ssh-encoding = { version = "0.2", features = ["bytes"] }
-ssh-key = { version = "0.6.3-internal.2", features = [
+ssh-key = { version = "0.6.7-internal.4", features = [
     "ed25519",
     "rsa",
     "rsa-sha1",
@@ -36,6 +36,7 @@ ssh-key = { version = "0.6.3-internal.2", features = [
     "p521",
     "encryption",
 ], package = "internal-russh-forked-ssh-key" }
+    "ppk",
 thiserror = "1.0.30"
 tokio = { version = "1.17.0" }
 tokio-stream = { version = "0.1.3", features = ["net", "sync"] }

russh-keys/src/format/mod.rs

@@ -44,6 +44,9 @@ enum Format {
 /// Decode a secret key, possibly deciphering it with the supplied
 /// password.
 pub fn decode_secret_key(secret: &str, password: Option<&str>) -> Result<PrivateKey, Error> {
+    if secret.trim().starts_with("PuTTY-User-Key-File-") {
+        return Ok(PrivateKey::from_ppk(secret, password.map(Into::into))?);
+    }
     let mut format = None;
     let secret = {
         let mut started = false;