fix RSA key signatures

src-tauri/src/credentials/ssh.rs

@@ -12,6 +12,8 @@ use serde::ser::{
     SerializeStruct,
 };
 use serde::de::{self, Visitor};
+use sha2::{Sha256, Sha512};
+use signature::{Signer, SignatureEncoding};
 use sqlx::{
     FromRow,
     Sqlite,
@@ -19,11 +21,15 @@ use sqlx::{
     Transaction,
     types::Uuid,
 };
-use ssh_agent_lib::proto::message::Identity;
+use ssh_agent_lib::proto::message::{
+    Identity,
+    SignRequest,
+};
+use ssh_encoding::Encode;
 use ssh_key::{
     Algorithm,
     LineEnding,
-    private::PrivateKey,
+    private::{PrivateKey, KeypairData},
     public::PublicKey,
 };
 use tokio_stream::StreamExt;
@@ -119,6 +125,33 @@ impl SshKey {
 
         Ok(identities)
     }
+
+    pub fn sign_request(&self, req: &SignRequest) -> Result<Vec<u8>, HandlerError> {
+        let mut sig = Vec::new();
+        match self.private_key.key_data() {
+            KeypairData::Rsa(keypair) => {
+                // 2 is the flag value for `SSH_AGENT_RSA_SHA2_256`
+                if req.flags & 2 > 0 {
+                    let signer = rsa::pkcs1v15::SigningKey::<Sha256>::try_from(keypair)?;
+                    let sig_data = signer.try_sign(&req.data)?.to_vec();
+                    "rsa-sha-256".encode(&mut sig)?;
+                    sig_data.encode(&mut sig)?;
+                }
+                else {
+                    let signer = rsa::pkcs1v15::SigningKey::<Sha512>::try_from(keypair)?;
+                    let sig_data = signer.try_sign(&req.data)?.to_vec();
+                    "rsa-sha2-512".encode(&mut sig)?;
+                    sig_data.encode(&mut sig)?;
+                }
+            },
+            _ => {
+                let sig_data = self.private_key.try_sign(&req.data)?;
+                self.algorithm.as_str().encode(&mut sig)?;
+                sig_data.as_bytes().encode(&mut sig)?;
+            },
+        }
+        Ok(sig)
+    }
 }