src/backup/manifest.rs: cleanup signature generation
This commit is contained in:
Dietmar Maurer
@ -3,22 +3,56 @@ use std::convert::TryFrom;
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use std::path::Path;
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use serde_json::{json, Value};
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use ::serde::{Deserialize, Serialize};
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use crate::backup::{BackupDir, CryptMode, CryptConfig};
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pub const MANIFEST_BLOB_NAME: &str = "index.json.blob";
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pub const CLIENT_LOG_BLOB_NAME: &str = "client.log.blob";
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mod hex_csum {
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use serde::{self, Deserialize, Serializer, Deserializer};
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pub fn serialize<S>(
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csum: &[u8; 32],
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serializer: S,
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) -> Result<S::Ok, S::Error>
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where
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S: Serializer,
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{
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let s = proxmox::tools::digest_to_hex(csum);
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serializer.serialize_str(&s)
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}
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pub fn deserialize<'de, D>(
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deserializer: D,
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) -> Result<[u8; 32], D::Error>
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where
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D: Deserializer<'de>,
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{
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let s = String::deserialize(deserializer)?;
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proxmox::tools::hex_to_digest(&s).map_err(serde::de::Error::custom)
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}
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}
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#[derive(Serialize, Deserialize)]
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#[serde(rename_all="kebab-case")]
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pub struct FileInfo {
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pub filename: String,
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pub crypt_mode: CryptMode,
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pub size: u64,
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#[serde(with = "hex_csum")]
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pub csum: [u8; 32],
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}
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#[derive(Serialize, Deserialize)]
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#[serde(rename_all="kebab-case")]
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pub struct BackupManifest {
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snapshot: BackupDir,
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backup_type: String,
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backup_id: String,
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backup_time: i64,
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files: Vec<FileInfo>,
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pub unprotected: Value,
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}
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#[derive(PartialEq)]
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@ -46,7 +80,13 @@ pub fn archive_type<P: AsRef<Path>>(
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impl BackupManifest {
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pub fn new(snapshot: BackupDir) -> Self {
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Self { files: Vec::new(), snapshot }
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Self {
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backup_type: snapshot.group().backup_type().into(),
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backup_id: snapshot.group().backup_id().into(),
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backup_time: snapshot.backup_time().timestamp(),
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files: Vec::new(),
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unprotected: json!({}),
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}
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}
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pub fn add_file(&mut self, filename: String, size: u64, csum: [u8; 32], crypt_mode: CryptMode) -> Result<(), Error> {
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@ -84,65 +124,97 @@ impl BackupManifest {
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Ok(())
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}
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pub fn signature(&self, crypt_config: &CryptConfig) -> [u8; 32] {
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// Generate cannonical json
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fn to_canonical_json(value: &Value, output: &mut String) -> Result<(), Error> {
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match value {
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Value::Null => bail!("got unexpected null value"),
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Value::String(_) => {
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output.push_str(&serde_json::to_string(value)?);
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},
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Value::Number(_) => {
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output.push_str(&serde_json::to_string(value)?);
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}
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Value::Bool(_) => {
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output.push_str(&serde_json::to_string(value)?);
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},
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Value::Array(list) => {
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output.push('[');
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for (i, item) in list.iter().enumerate() {
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if i != 0 { output.push(','); }
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Self::to_canonical_json(item, output)?;
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}
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output.push(']');
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}
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Value::Object(map) => {
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output.push('{');
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let mut keys: Vec<String> = map.keys().map(|s| s.clone()).collect();
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keys.sort();
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for (i, key) in keys.iter().enumerate() {
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let item = map.get(key).unwrap();
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if i != 0 { output.push(','); }
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let mut data = String::new();
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data.push_str(self.snapshot.group().backup_type());
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data.push('\n');
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data.push_str(self.snapshot.group().backup_id());
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data.push('\n');
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data.push_str(&format!("{}", self.snapshot.backup_time().timestamp()));
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data.push('\n');
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data.push('\n');
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for info in self.files.iter() {
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data.push_str(&info.filename);
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data.push('\n');
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data.push_str(match info.crypt_mode {
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CryptMode::None => "None",
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CryptMode::SignOnly => "SignOnly",
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CryptMode::Encrypt => "Encrypt",
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});
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data.push('\n');
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data.push_str(&format!("{}", info.size));
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data.push('\n');
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data.push_str(&proxmox::tools::digest_to_hex(&info.csum));
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data.push('\n');
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data.push('\n');
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output.push_str(&serde_json::to_string(&Value::String(key.clone()))?);
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output.push(':');
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Self::to_canonical_json(item, output)?;
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}
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output.push('}');
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}
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}
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crypt_config.compute_auth_tag(data.as_bytes())
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Ok(())
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}
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pub fn into_json(self, crypt_config: Option<&CryptConfig>) -> Value {
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/// Compute manifest signature
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///
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/// By generating a HMAC SHA256 over the canonical json
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/// representation, The 'unpreotected' property is excluded.
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pub fn signature(&self, crypt_config: &CryptConfig) -> Result<[u8; 32], Error> {
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let mut manifest = json!({
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"backup-type": self.snapshot.group().backup_type(),
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"backup-id": self.snapshot.group().backup_id(),
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"backup-time": self.snapshot.backup_time().timestamp(),
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"files": self.files.iter()
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.fold(Vec::new(), |mut acc, info| {
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acc.push(json!({
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"filename": info.filename,
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"crypt-mode": info.crypt_mode,
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"size": info.size,
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"csum": proxmox::tools::digest_to_hex(&info.csum),
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}));
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acc
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})
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});
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let mut signed_data = serde_json::to_value(&self)?;
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signed_data.as_object_mut().unwrap().remove("unprotected"); // exclude
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let mut canonical = String::new();
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Self::to_canonical_json(&signed_data, &mut canonical)?;
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let sig = crypt_config.compute_auth_tag(canonical.as_bytes());
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Ok(sig)
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}
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/// Converts the Manifest into json string, and add a signature if there is a crypt_config.
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pub fn into_string(self, crypt_config: Option<&CryptConfig>) -> Result<String, Error> {
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let mut manifest = serde_json::to_value(&self)?;
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if let Some(crypt_config) = crypt_config {
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let sig = self.signature(crypt_config);
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let sig = self.signature(crypt_config)?;
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manifest["signature"] = proxmox::tools::digest_to_hex(&sig).into();
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}
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manifest
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let manifest = serde_json::to_string_pretty(&manifest).unwrap().into();
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Ok(manifest)
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}
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/// Try to read the manifest. This verifies the signature if there is a crypt_config.
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pub fn from_data(data: &[u8], crypt_config: Option<&CryptConfig>) -> Result<BackupManifest, Error> {
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let json: Value = serde_json::from_slice(data)?;
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let signature = json["signature"].as_str().map(String::from);
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let manifest = BackupManifest::try_from(json)?;
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if let Some(ref crypt_config) = crypt_config {
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if let Some(signature) = signature {
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let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(crypt_config)?);
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if signature != expected_signature {
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bail!("wrong signature in manifest");
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}
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} else {
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// not signed: warn/fail?
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}
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}
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Ok(manifest)
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}
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}
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impl TryFrom<super::DataBlob> for BackupManifest {
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type Error = Error;
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@ -199,3 +271,45 @@ impl TryFrom<Value> for BackupManifest {
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}
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}
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#[test]
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fn test_manifest_signature() -> Result<(), Error> {
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use crate::backup::{KeyDerivationConfig};
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let pw = b"test";
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let kdf = KeyDerivationConfig::Scrypt {
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n: 65536,
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r: 8,
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p: 1,
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salt: Vec::new(),
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};
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let testkey = kdf.derive_key(pw)?;
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let crypt_config = CryptConfig::new(testkey)?;
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let snapshot: BackupDir = "host/elsa/2020-06-26T13:56:05Z".parse()?;
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let mut manifest = BackupManifest::new(snapshot);
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manifest.add_file("test1.img.fidx".into(), 200, [1u8; 32], CryptMode::Encrypt)?;
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manifest.add_file("abc.blob".into(), 200, [2u8; 32], CryptMode::None)?;
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manifest.unprotected["note"] = "This is not protected by the signature.".into();
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let text = manifest.into_string(Some(&crypt_config))?;
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let manifest: Value = serde_json::from_str(&text)?;
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let signature = manifest["signature"].as_str().unwrap().to_string();
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assert_eq!(signature, "d7b446fb7db081662081d4b40fedd858a1d6307a5aff4ecff7d5bf4fd35679e9");
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let manifest = BackupManifest::try_from(manifest)?;
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let expected_signature = proxmox::tools::digest_to_hex(&manifest.signature(&crypt_config)?);
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assert_eq!(signature, expected_signature);
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Ok(())
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}
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