move

lib/ssh-transport/src/key.rs

@@ -0,0 +1,59 @@
+//! Operations on SSH keys.
+
+use std::fmt::Display;
+
+use base64::Engine;
+
+use crate::parse::{self, ParseError, Parser, Writer};
+
+pub enum SshPubkey {
+    Ed25519 { public_key: [u8; 32] },
+}
+
+impl SshPubkey {
+    /// Parses an SSH public key from its wire encoding as specified in
+    /// RFC4253, RFC5656, and RFC8709.
+    pub fn from_wire_encoding(bytes: &[u8]) -> parse::Result<Self> {
+        let mut p = Parser::new(bytes);
+        let alg = p.utf8_string()?;
+
+        let k = match alg {
+            "ssh-ed25519" => {
+                let len = p.u32()?;
+                if len != 32 {
+                    return Err(ParseError(format!("incorrect ed25519 len: {len}")));
+                }
+                let public_key = p.array::<32>()?;
+                Self::Ed25519 { public_key }
+            }
+            _ => return Err(ParseError(format!("unsupported key type: {alg}"))),
+        };
+        Ok(k)
+    }
+
+    pub fn to_wire_encoding(&self) -> Vec<u8> {
+        let mut p = Writer::new();
+        match self {
+            Self::Ed25519 { public_key } => {
+                p.string(b"ssh-ed25519");
+                p.string(public_key);
+            }
+        }
+        p.finish()
+    }
+}
+
+impl Display for SshPubkey {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Ed25519 { .. } => {
+                let encoded_pubkey = b64encode(&self.to_wire_encoding());
+                write!(f, "ssh-ed25519 {encoded_pubkey}")
+            }
+        }
+    }
+}
+
+fn b64encode(bytes: &[u8]) -> String {
+    base64::prelude::BASE64_STANDARD_NO_PAD.encode(bytes)
+}