good stuff

lib/ssh-agent-client/src/lib.rs

@@ -45,7 +45,7 @@ impl Request {
             } => {
                 p.u8(numbers::SSH_AGENTC_ADD_IDENTITY);
                 p.string(key_type.as_bytes());
-                p.write(&key_contents);
+                p.raw(&key_contents);
                 p.string(key_comment.as_bytes());
             }
             Self::RemoveAllIdentities => p.u8(numbers::SSH_AGENTC_REMOVE_ALL_IDENTITIES),

lib/ssh-keys/Cargo.toml

@@ -7,5 +7,7 @@ edition = "2021"
 aes = "0.8.4"
 bcrypt-pbkdf = "0.10.0"
 ctr = "0.9.2"
+ed25519-dalek = { version = "2.1.1", features = ["rand_core"] }
 pem = "3.0.4"
+rand = "0.8.5"
 ssh-transport = { path = "../ssh-transport" }

lib/ssh-keys/src/crypto.rs

@@ -1,7 +1,9 @@
 use std::str::FromStr;
 
 use aes::cipher::{KeySizeUser, StreamCipher};
-use ssh_transport::parse::{self, Parser};
+use ssh_transport::parse::{self, Parser, Writer};
+
+use crate::PrivateKeyType;
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Cipher {
@@ -27,6 +29,13 @@ impl FromStr for Cipher {
 }
 
 impl Cipher {
+    pub fn name(&self) -> &'static str {
+        match self {
+            Self::None => "none",
+            Self::Aes256Ctr => "aes256-ctr",
+        }
+    }
+
     pub(crate) fn key_iv_size(&self) -> (usize, usize) {
         match self {
             Cipher::None => (0, 0),
@@ -34,7 +43,8 @@ impl Cipher {
         }
     }
 
-    pub(crate) fn decrypt_in_place(&self, data: &mut [u8], key: &[u8], iv: &[u8]) {
+    /// Decrypt or encrypt a buffer in place (the same operation due to stream ciphers).
+    pub(crate) fn crypt_in_place(&self, data: &mut [u8], key: &[u8], iv: &[u8]) {
         match self {
             Cipher::None => unreachable!("cannot decrypt none cipher"),
             Cipher::Aes256Ctr => {
@@ -84,6 +94,25 @@ impl Kdf {
         Ok(kdf)
     }
 
+    pub fn name(&self) -> &'static str {
+        match self {
+            Self::None => "none",
+            Self::BCrypt { .. } => "bcrypt",
+        }
+    }
+
+    pub fn options(&self) -> Vec<u8> {
+        match self {
+            Self::None => Vec::new(),
+            Self::BCrypt { salt, rounds } => {
+                let mut opts = Writer::new();
+                opts.string(salt);
+                opts.u32(*rounds);
+                opts.finish()
+            }
+        }
+    }
+
     pub(crate) fn derive(&self, passphrase: &str, output: &mut [u8]) -> parse::Result<()> {
         match self {
             Self::None => unreachable!("should not attempt to derive passphrase from none"),
@@ -95,3 +124,24 @@ impl Kdf {
         }
     }
 }
+
+pub enum KeyType {
+    Ed25519,
+}
+
+pub struct KeyGenerationParams {
+    pub key_type: KeyType,
+}
+
+pub(crate) fn generate_private_key(params: KeyGenerationParams) -> PrivateKeyType {
+    match params.key_type {
+        KeyType::Ed25519 => {
+            let private_key = ed25519_dalek::SigningKey::generate(&mut rand::rngs::OsRng);
+
+            PrivateKeyType::Ed25519 {
+                public_key: private_key.verifying_key().to_bytes(),
+                private_key: private_key.to_bytes(),
+            }
+        }
+    }
+}

lib/ssh-keys/src/lib.rs

@@ -3,9 +3,13 @@ mod crypto;
 use crypto::{Cipher, Kdf};
 use ssh_transport::{
     key::PublicKey,
-    parse::{self, Parser},
+    parse::{self, Parser, Writer},
 };
 
+// TODO: good typed error messages so the user knows what's going on
+
+pub use crypto::{KeyGenerationParams, KeyType};
+
 pub struct EncryptedPrivateKeys {
     pub public_keys: Vec<PublicKey>,
     pub cipher: Cipher,
@@ -16,6 +20,7 @@ pub struct EncryptedPrivateKeys {
 pub struct PlaintextPrivateKey {
     pub private_key: PrivateKeyType,
     pub comment: String,
+    checkint: u32,
 }
 
 pub enum PrivateKeyType {
@@ -29,7 +34,7 @@ const MAGIC: &[u8; 15] = b"openssh-key-v1\0";
 
 impl EncryptedPrivateKeys {
     /// Parse OpenSSH private keys, either armored or not.
-    pub fn parse_unencrypted(content: &[u8]) -> parse::Result<Self> {
+    pub fn parse(content: &[u8]) -> parse::Result<Self> {
         // https://github.com/openssh/openssh-portable/blob/a76a6b85108e3032c8175611ecc5746e7131f876/PROTOCOL.key
         let pem: pem::Pem; // lifetime extension
         let content = if content.starts_with(b"openssh-key-v1") {
@@ -76,14 +81,35 @@ impl EncryptedPrivateKeys {
         })
     }
 
+    pub fn to_bytes_armored(&self) -> String {
+        let content = self.to_bytes();
+        let pem = pem::Pem::new("OPENSSH PRIVATE KEY", content);
+        pem::encode(&pem)
+    }
+
+    pub fn to_bytes(&self) -> Vec<u8> {
+        let mut p = Writer::new();
+        p.array(*MAGIC);
+        p.string(self.cipher.name().as_bytes());
+        p.string(self.kdf.name().as_bytes());
+        p.string(&self.kdf.options());
+
+        p.u32(self.public_keys.len() as u32);
+
+        for pubkey in &self.public_keys {
+            p.string(&pubkey.to_wire_encoding());
+        }
+
+        p.string(&self.encrypted_private_keys);
+
+        p.finish()
+    }
+
     pub fn requires_passphrase(&self) -> bool {
         (!matches!(self.kdf, Kdf::None)) && (!matches!(self.cipher, Cipher::None))
     }
 
-    pub fn parse_private(
-        &self,
-        passphrase: Option<&str>,
-    ) -> parse::Result<Vec<PlaintextPrivateKey>> {
+    pub fn decrypt_encrypted_part(&self, passphrase: Option<&str>) -> parse::Result<Vec<u8>> {
         let mut data = self.encrypted_private_keys.clone();
         if self.requires_passphrase() {
             let Some(passphrase) = passphrase else {
@@ -98,16 +124,22 @@ impl EncryptedPrivateKeys {
             let mut output = vec![0; key_size + iv_size];
             self.kdf.derive(passphrase, &mut output)?;
             let (key, iv) = output.split_at(key_size);
-            self.cipher.decrypt_in_place(&mut data, &key, &iv);
+            self.cipher.crypt_in_place(&mut data, &key, &iv);
         }
+        Ok(data)
+    }
+
+    pub fn parse_private(
+        &self,
+        passphrase: Option<&str>,
+    ) -> parse::Result<Vec<PlaintextPrivateKey>> {
+        let data = self.decrypt_encrypted_part(passphrase)?;
 
         let mut p = Parser::new(&data);
         let checkint1 = p.u32()?;
         let checkint2 = p.u32()?;
         if checkint1 != checkint2 {
-            return Err(parse::ParseError(format!(
-                "failed sanity check, invalid key or password ({checkint1}!={checkint2})"
-            )));
+            return Err(parse::ParseError(format!("invalid key or password")));
         }
 
         let mut result_keys = Vec::new();
@@ -115,6 +147,7 @@ impl EncryptedPrivateKeys {
         for pubkey in &self.public_keys {
             let keytype = match pubkey {
                 PublicKey::Ed25519 { public_key } => {
+                    // <https://datatracker.ietf.org/doc/html/draft-miller-ssh-agent#section-3.2.3>
                     let alg = p.utf8_string()?;
                     if alg != "ssh-ed25519" {
                         return Err(parse::ParseError(format!(
@@ -150,6 +183,7 @@ impl EncryptedPrivateKeys {
             result_keys.push(PlaintextPrivateKey {
                 private_key: keytype,
                 comment: comment.to_owned(),
+                checkint: checkint1,
             });
         }
 
@@ -169,6 +203,98 @@ impl EncryptedPrivateKeys {
     }
 }
 
+pub struct KeyEncryptionParams {
+    pub cipher: Cipher,
+    pub kdf: Kdf,
+    pub passphrase: Option<String>,
+}
+
+impl KeyEncryptionParams {
+    pub fn secure_or_none(passphrase: String) -> Self {
+        if passphrase.is_empty() {
+            Self {
+                cipher: Cipher::None,
+                kdf: Kdf::None,
+                passphrase: None,
+            }
+        } else {
+            Self {
+                cipher: Cipher::Aes256Ctr,
+                kdf: Kdf::BCrypt {
+                    salt: rand::random(),
+                    rounds: 24,
+                },
+                passphrase: Some(passphrase),
+            }
+        }
+    }
+}
+
+impl PlaintextPrivateKey {
+    pub fn generate(comment: String, params: KeyGenerationParams) -> Self {
+        let keytype = crypto::generate_private_key(params);
+        Self {
+            comment,
+            private_key: keytype,
+            checkint: rand::random(),
+        }
+    }
+
+    pub fn encrypt(&self, params: KeyEncryptionParams) -> parse::Result<EncryptedPrivateKeys> {
+        let public_keys = vec![self.private_key.public_key()];
+
+        let mut enc = Writer::new();
+        enc.u32(self.checkint);
+        enc.u32(self.checkint);
+
+        match self.private_key {
+            PrivateKeyType::Ed25519 {
+                public_key,
+                private_key,
+            } => {
+                // <https://datatracker.ietf.org/doc/html/draft-miller-ssh-agent#section-3.2.3>
+                enc.string(b"ssh-ed25519");
+                enc.string(&public_key);
+                let combined = private_key.len() + public_key.len();
+                enc.u32(combined as u32);
+                enc.raw(&private_key);
+                enc.raw(&public_key);
+                enc.string(&self.comment.as_bytes());
+            }
+        }
+
+        // uh..., i don't really now how much i need to pad so YOLO this here
+        // TODO: pad properly.
+        enc.u8(1);
+        enc.u8(2);
+
+        let mut encrypted_private_keys = enc.finish();
+
+        match params.cipher {
+            Cipher::None => {}
+            Cipher::Aes256Ctr => {
+                let (key_size, iv_size) = params.cipher.key_iv_size();
+
+                let mut output = vec![0; key_size + iv_size];
+                params
+                    .kdf
+                    .derive(&params.passphrase.unwrap(), &mut output)?;
+                let (key, iv) = output.split_at(key_size);
+                params
+                    .cipher
+                    .crypt_in_place(&mut encrypted_private_keys, &key, &iv);
+            }
+        }
+
+        Ok(EncryptedPrivateKeys {
+            public_keys,
+            cipher: params.cipher,
+            kdf: params.kdf,
+            encrypted_private_keys,
+        })
+    }
+}
+
 impl PrivateKeyType {
     pub fn public_key(&self) -> PublicKey {
         match *self {
@@ -179,7 +305,7 @@ impl PrivateKeyType {
 
 #[cfg(test)]
 mod tests {
-    use crate::{Cipher, EncryptedPrivateKeys, Kdf, PrivateKeyType};
+    use crate::{Cipher, EncryptedPrivateKeys, Kdf, KeyEncryptionParams, PrivateKeyType};
 
     // ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIHPaiIO6MePXM/QCJWVge1k4dsiefPr4taP9VJbCtXdx uwu
     // Password: 'test'
@@ -206,7 +332,7 @@ zukcSwhnKrg+wzw7/JZQAAAAA3V3dQEC
 
     #[test]
     fn ed25519_none() {
-        let keys = EncryptedPrivateKeys::parse_unencrypted(TEST_ED25519_NONE).unwrap();
+        let keys = EncryptedPrivateKeys::parse(TEST_ED25519_NONE).unwrap();
         assert_eq!(keys.public_keys.len(), 1);
         assert_eq!(keys.cipher, Cipher::None);
         assert_eq!(keys.kdf, Kdf::None);
@@ -218,9 +344,22 @@ zukcSwhnKrg+wzw7/JZQAAAAA3V3dQEC
         assert!(matches!(key.private_key, PrivateKeyType::Ed25519 { .. }));
     }
 
+    #[test]
+    fn roundtrip_ed25519_none() {
+        let keys = EncryptedPrivateKeys::parse(TEST_ED25519_NONE).unwrap();
+        let decrypted = keys.parse_private(None).unwrap();
+
+        let encrypted = decrypted[0]
+            .encrypt(KeyEncryptionParams::secure_or_none("".to_owned()))
+            .unwrap();
+
+        let bytes = encrypted.to_bytes();
+        assert_eq!(pem::parse(TEST_ED25519_NONE).unwrap().contents(), bytes);
+    }
+
     #[test]
     fn ed25519_aes256ctr() {
-        let keys = EncryptedPrivateKeys::parse_unencrypted(TEST_ED25519_AES256_CTR).unwrap();
+        let keys = EncryptedPrivateKeys::parse(TEST_ED25519_AES256_CTR).unwrap();
         assert_eq!(keys.public_keys.len(), 1);
         assert_eq!(keys.cipher, Cipher::Aes256Ctr);
         assert!(matches!(keys.kdf, Kdf::BCrypt { .. }));
@@ -231,4 +370,17 @@ zukcSwhnKrg+wzw7/JZQAAAAA3V3dQEC
         assert_eq!(key.comment, "uwu");
         assert!(matches!(key.private_key, PrivateKeyType::Ed25519 { .. }));
     }
+
+    #[test]
+    fn roundtrip_aes256ctr() {
+        let keys = EncryptedPrivateKeys::parse(TEST_ED25519_NONE).unwrap();
+        let decrypted = keys.parse_private(None).unwrap();
+
+        let encrypted = decrypted[0]
+            .encrypt(KeyEncryptionParams::secure_or_none("".to_owned()))
+            .unwrap();
+
+        let bytes = encrypted.to_bytes();
+        assert_eq!(pem::parse(TEST_ED25519_NONE).unwrap().contents(), bytes);
+    }
 }

lib/ssh-transport/src/parse.rs

@@ -116,19 +116,19 @@ impl Writer {
     }
 
     pub fn u8(&mut self, v: u8) {
-        self.write(&[v]);
+        self.raw(&[v]);
     }
 
     pub fn u32(&mut self, v: u32) {
-        self.write(&u32::to_be_bytes(v));
+        self.raw(&u32::to_be_bytes(v));
     }
 
-    pub fn write(&mut self, v: &[u8]) {
+    pub fn raw(&mut self, v: &[u8]) {
         self.0.extend_from_slice(v);
     }
 
     pub fn array<const N: usize>(&mut self, arr: [u8; N]) {
-        self.write(&arr);
+        self.raw(&arr);
     }
 
     pub fn name_list(&mut self, list: NameList<'_>) {
@@ -146,12 +146,12 @@ impl Writer {
         if pad_zero {
             self.u8(0);
         }
-        self.write(bytes);
+        self.raw(bytes);
     }
 
     pub fn string(&mut self, data: &[u8]) {
         self.u32(data.len() as u32);
-        self.write(data);
+        self.raw(data);
     }
 
     pub fn bool(&mut self, v: bool) {