first commit

src/gpu_rent/ssh_keys.py

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+"""Ed25519 key at ~/.gpu-rent/id_ed25519 (no passphrase)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+
+from gpu_rent.paths import default_ssh_key_path
+
+
+def public_path(private: Path) -> Path:
+    return private.with_suffix(private.suffix + ".pub") if private.suffix else Path(str(private) + ".pub")
+
+
+def ensure_ed25519(path: Path | None = None) -> tuple[Path, Path]:
+    private = path or default_ssh_key_path()
+    pub = public_path(private)
+    if private.is_file() and pub.is_file():
+        return private, pub
+
+    private.parent.mkdir(parents=True, exist_ok=True)
+    key = Ed25519PrivateKey.generate()
+    private_bytes = key.private_bytes(
+        encoding=serialization.Encoding.PEM,
+        format=serialization.PrivateFormat.OpenSSH,
+        encryption_algorithm=serialization.NoEncryption(),
+    )
+    public_bytes = key.public_key().public_bytes(
+        encoding=serialization.Encoding.OpenSSH,
+        format=serialization.PublicFormat.OpenSSH,
+    ) + b" gpu-rent\n"
+
+    private.write_bytes(private_bytes)
+    try:
+        private.chmod(0o600)
+    except OSError:
+        pass
+    pub.write_bytes(public_bytes)
+    return private, pub
+
+
+def key_ready(path: Path | None = None) -> bool:
+    private = path or default_ssh_key_path()
+    return private.is_file() and public_path(private).is_file()