src/backup/key_derivation.rs: move kdf code into separate file

src/backup/key_derivation.rs

@@ -0,0 +1,180 @@
+use failure::*;
+
+use serde::{Deserialize, Serialize};
+use chrono::{Local, TimeZone, DateTime};
+
+#[derive(Deserialize, Serialize, Debug)]
+pub enum KeyDerivationConfig {
+    Scrypt {
+        n: u64,
+        r: u64,
+        p: u64,
+        #[serde(with = "proxmox::tools::serde::bytes_as_base64")]
+        salt: Vec<u8>,
+    },
+    PBKDF2 {
+        iter: usize,
+        #[serde(with = "proxmox::tools::serde::bytes_as_base64")]
+        salt: Vec<u8>,
+    },
+}
+
+impl KeyDerivationConfig {
+
+    /// Derive a key from provided passphrase
+    pub fn derive_key(&self, passphrase: &[u8]) -> Result<[u8; 32], Error> {
+
+        let mut key = [0u8; 32];
+
+        match self {
+            KeyDerivationConfig::Scrypt { n, r, p, salt } => {
+                // estimated scrypt memory usage is 128*r*n*p
+                openssl::pkcs5::scrypt(
+                    passphrase,
+                    &salt,
+                    *n, *r, *p,
+                    1025*1024*1024,
+                    &mut key,
+                )?;
+
+                Ok(key)
+            }
+            KeyDerivationConfig::PBKDF2 { iter, salt } => {
+
+                 openssl::pkcs5::pbkdf2_hmac(
+                    passphrase,
+                    &salt,
+                    *iter,
+                    openssl::hash::MessageDigest::sha256(),
+                    &mut key,
+                )?;
+
+                Ok(key)
+            }
+        }
+    }
+}
+
+#[derive(Deserialize, Serialize, Debug)]
+pub struct KeyConfig {
+    kdf: Option<KeyDerivationConfig>,
+    #[serde(with = "proxmox::tools::serde::date_time_as_rfc3339")]
+    created: DateTime<Local>,
+    #[serde(with = "proxmox::tools::serde::bytes_as_base64")]
+    data: Vec<u8>,
+ }
+
+
+pub fn store_key_with_passphrase(
+    path: &std::path::Path,
+    raw_key: &[u8],
+    passphrase: &[u8],
+    replace: bool,
+) -> Result<(), Error> {
+
+    let salt = proxmox::sys::linux::random_data(32)?;
+
+    let kdf = KeyDerivationConfig::Scrypt {
+        n: 65536,
+        r: 8,
+        p: 1,
+        salt,
+    };
+
+    let derived_key = kdf.derive_key(passphrase)?;
+
+    let cipher = openssl::symm::Cipher::aes_256_gcm();
+
+    let iv = proxmox::sys::linux::random_data(16)?;
+    let mut tag = [0u8; 16];
+
+    let encrypted_key = openssl::symm::encrypt_aead(
+        cipher,
+        &derived_key,
+        Some(&iv),
+        b"",
+        &raw_key,
+        &mut tag,
+    )?;
+
+    let mut enc_data = vec![];
+    enc_data.extend_from_slice(&iv);
+    enc_data.extend_from_slice(&tag);
+    enc_data.extend_from_slice(&encrypted_key);
+
+    let created =  Local.timestamp(Local::now().timestamp(), 0);
+
+
+    let key_config = KeyConfig {
+        kdf: Some(kdf),
+        created,
+        data: enc_data,
+    };
+
+    let data = serde_json::to_string(&key_config)?;
+
+    use std::io::Write;
+
+    try_block!({
+        if replace {
+            let mode = nix::sys::stat::Mode::S_IRUSR | nix::sys::stat::Mode::S_IWUSR;
+            crate::tools::file_set_contents(&path, data.as_bytes(), Some(mode))?;
+        } else {
+            use std::os::unix::fs::OpenOptionsExt;
+
+            let mut file = std::fs::OpenOptions::new()
+                .write(true)
+                .mode(0o0600)
+                .create_new(true)
+                .open(&path)?;
+
+            file.write_all(data.as_bytes())?;
+        }
+
+        Ok(())
+    }).map_err(|err: Error| format_err!("Unable to create file {:?} - {}", path, err))?;
+
+    Ok(())
+}
+
+pub fn load_and_decrtypt_key(path: &std::path::Path, passphrase: fn() -> Result<Vec<u8>, Error>) -> Result<Vec<u8>, Error> {
+
+    let raw = crate::tools::file_get_contents(&path)?;
+    let data = String::from_utf8(raw)?;
+
+    let key_config: KeyConfig = serde_json::from_str(&data)?;
+
+    let raw_data = key_config.data;
+
+    if let Some(kdf) = key_config.kdf {
+
+        let passphrase = passphrase()?;
+        if passphrase.len() < 5 {
+            bail!("Passphrase is too short!");
+        }
+
+        let derived_key = kdf.derive_key(&passphrase)?;
+
+        if raw_data.len() < 32 {
+            bail!("Unable to encode key - short data");
+        }
+        let iv = &raw_data[0..16];
+        let tag = &raw_data[16..32];
+        let enc_data = &raw_data[32..];
+
+        let cipher = openssl::symm::Cipher::aes_256_gcm();
+
+        let decr_data = openssl::symm::decrypt_aead(
+            cipher,
+            &derived_key,
+            Some(&iv),
+            b"", //??
+            &enc_data,
+            &tag,
+        ).map_err(|err| format_err!("Unable to decrypt key - {}", err))?;
+
+        Ok(decr_data)
+    } else {
+        Ok(raw_data)
+    }
+}