[pbs-devel] [PATCH v3 proxmox-backup 05/20] proxmox_client_tools: move common key related functions to key_source.rs

[Stefan Reiter <s.reiter@proxmox.com>]

Add a new module containing key-related functions and schemata from all
over, code moved is not changed as much as possible.

Requires adapting some 'use' statements across proxmox-backup-client and
putting the XDG helpers quite cozily into proxmox_client_tools/mod.rs

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---

v2:
* don't move entire key.rs, just what is necessary

 src/bin/proxmox-backup-client.rs           | 453 +---------------
 src/bin/proxmox_backup_client/benchmark.rs |   4 +-
 src/bin/proxmox_backup_client/catalog.rs   |   3 +-
 src/bin/proxmox_backup_client/key.rs       | 112 +---
 src/bin/proxmox_backup_client/mod.rs       |  28 -
 src/bin/proxmox_backup_client/mount.rs     |   4 +-
 src/bin/proxmox_backup_client/snapshot.rs  |   4 +-
 src/bin/proxmox_client_tools/key_source.rs | 573 +++++++++++++++++++++
 src/bin/proxmox_client_tools/mod.rs        |  48 +-
 9 files changed, 631 insertions(+), 598 deletions(-)
 create mode 100644 src/bin/proxmox_client_tools/key_source.rs

diff --git a/src/bin/proxmox-backup-client.rs b/src/bin/proxmox-backup-client.rs
index 45b26c7a..50703dcb 100644
--- a/src/bin/proxmox-backup-client.rs
+++ b/src/bin/proxmox-backup-client.rs
@@ -1,7 +1,5 @@
 use std::collections::HashSet;
-use std::convert::TryFrom;
 use std::io::{self, Read, Write, Seek, SeekFrom};
-use std::os::unix::io::{FromRawFd, RawFd};
 use std::path::{Path, PathBuf};
 use std::pin::Pin;
 use std::sync::{Arc, Mutex};
@@ -19,7 +17,7 @@ use pathpatterns::{MatchEntry, MatchType, PatternFlag};
 use proxmox::{
     tools::{
         time::{strftime_local, epoch_i64},
-        fs::{file_get_contents, file_get_json, replace_file, CreateOptions, image_size},
+        fs::{file_get_json, replace_file, CreateOptions, image_size},
     },
     api::{
         api,
@@ -71,8 +69,18 @@ use proxmox_backup::backup::{
 mod proxmox_backup_client;
 use proxmox_backup_client::*;
 
-mod proxmox_client_tools;
-use proxmox_client_tools::*;
+pub mod proxmox_client_tools;
+use proxmox_client_tools::{
+    complete_archive_name, complete_auth_id, complete_backup_group, complete_backup_snapshot,
+    complete_backup_source, complete_chunk_size, complete_group_or_snapshot,
+    complete_img_archive_name, complete_pxar_archive_name, complete_repository, connect,
+    extract_repository_from_value,
+    key_source::{
+        crypto_parameters, format_key_source, get_encryption_key_password, KEYFD_SCHEMA,
+        KEYFILE_SCHEMA, MASTER_PUBKEY_FD_SCHEMA, MASTER_PUBKEY_FILE_SCHEMA,
+    },
+    CHUNK_SIZE_SCHEMA, REPO_URL_SCHEMA,
+};
 
 fn record_repository(repo: &BackupRepository) {
 
@@ -503,437 +511,6 @@ fn spawn_catalog_upload(
     Ok(CatalogUploadResult { catalog_writer, result: catalog_result_rx })
 }
 
-#[derive(Clone, Debug, Eq, PartialEq)]
-enum KeySource {
-    DefaultKey,
-    Fd,
-    Path(String),
-}
-
-fn format_key_source(source: &KeySource, key_type: &str) -> String {
-    match source {
-        KeySource::DefaultKey => format!("Using default {} key..", key_type),
-        KeySource::Fd => format!("Using {} key from file descriptor..", key_type),
-        KeySource::Path(path) => format!("Using {} key from '{}'..", key_type, path),
-    }
-}
-
-#[derive(Clone, Debug, Eq, PartialEq)]
-struct KeyWithSource {
-    pub source: KeySource,
-    pub key: Vec<u8>,
-}
-
-impl KeyWithSource {
-    pub fn from_fd(key: Vec<u8>) -> Self {
-        Self {
-            source: KeySource::Fd,
-            key,
-        }
-    }
-
-    pub fn from_default(key: Vec<u8>) -> Self {
-        Self {
-            source: KeySource::DefaultKey,
-            key,
-        }
-    }
-
-    pub fn from_path(path: String, key: Vec<u8>) -> Self {
-        Self {
-            source: KeySource::Path(path),
-            key,
-        }
-    }
-}
-
-#[derive(Debug, Eq, PartialEq)]
-struct CryptoParams {
-    mode: CryptMode,
-    enc_key: Option<KeyWithSource>,
-    // FIXME switch to openssl::rsa::rsa<openssl::pkey::Public> once that is Eq?
-    master_pubkey: Option<KeyWithSource>,
-}
-
-fn crypto_parameters(param: &Value) -> Result<CryptoParams, Error> {
-    let keyfile = match param.get("keyfile") {
-        Some(Value::String(keyfile)) => Some(keyfile),
-        Some(_) => bail!("bad --keyfile parameter type"),
-        None => None,
-    };
-
-    let key_fd = match param.get("keyfd") {
-        Some(Value::Number(key_fd)) => Some(
-            RawFd::try_from(key_fd
-                .as_i64()
-                .ok_or_else(|| format_err!("bad key fd: {:?}", key_fd))?
-            )
-            .map_err(|err| format_err!("bad key fd: {:?}: {}", key_fd, err))?
-        ),
-        Some(_) => bail!("bad --keyfd parameter type"),
-        None => None,
-    };
-
-    let master_pubkey_file = match param.get("master-pubkey-file") {
-        Some(Value::String(keyfile)) => Some(keyfile),
-        Some(_) => bail!("bad --master-pubkey-file parameter type"),
-        None => None,
-    };
-
-    let master_pubkey_fd = match param.get("master-pubkey-fd") {
-        Some(Value::Number(key_fd)) => Some(
-            RawFd::try_from(key_fd
-                .as_i64()
-                .ok_or_else(|| format_err!("bad master public key fd: {:?}", key_fd))?
-            )
-            .map_err(|err| format_err!("bad public master key fd: {:?}: {}", key_fd, err))?
-        ),
-        Some(_) => bail!("bad --master-pubkey-fd parameter type"),
-        None => None,
-    };
-
-    let mode: Option<CryptMode> = match param.get("crypt-mode") {
-        Some(mode) => Some(serde_json::from_value(mode.clone())?),
-        None => None,
-    };
-
-    let key = match (keyfile, key_fd) {
-        (None, None) => None,
-        (Some(_), Some(_)) => bail!("--keyfile and --keyfd are mutually exclusive"),
-        (Some(keyfile), None) => Some(KeyWithSource::from_path(
-            keyfile.clone(),
-            file_get_contents(keyfile)?,
-        )),
-        (None, Some(fd)) => {
-            let input = unsafe { std::fs::File::from_raw_fd(fd) };
-            let mut data = Vec::new();
-            let _len: usize = { input }.read_to_end(&mut data).map_err(|err| {
-                format_err!("error reading encryption key from fd {}: {}", fd, err)
-            })?;
-            Some(KeyWithSource::from_fd(data))
-        }
-    };
-
-    let master_pubkey = match (master_pubkey_file, master_pubkey_fd) {
-        (None, None) => None,
-        (Some(_), Some(_)) => bail!("--keyfile and --keyfd are mutually exclusive"),
-        (Some(keyfile), None) => Some(KeyWithSource::from_path(
-            keyfile.clone(),
-            file_get_contents(keyfile)?,
-        )),
-        (None, Some(fd)) => {
-            let input = unsafe { std::fs::File::from_raw_fd(fd) };
-            let mut data = Vec::new();
-            let _len: usize = { input }
-                .read_to_end(&mut data)
-                .map_err(|err| format_err!("error reading master key from fd {}: {}", fd, err))?;
-            Some(KeyWithSource::from_fd(data))
-        }
-    };
-
-    let res = match mode {
-        // no crypt mode, enable encryption if keys are available
-        None => match (key, master_pubkey) {
-            // only default keys if available
-            (None, None) => match key::read_optional_default_encryption_key()? {
-                None => CryptoParams { mode: CryptMode::None, enc_key: None, master_pubkey: None },
-                enc_key => {
-                    let master_pubkey = key::read_optional_default_master_pubkey()?;
-                    CryptoParams {
-                        mode: CryptMode::Encrypt,
-                        enc_key,
-                        master_pubkey,
-                    }
-                },
-            },
-
-            // explicit master key, default enc key needed
-            (None, master_pubkey) => match key::read_optional_default_encryption_key()? {
-                None => bail!("--master-pubkey-file/--master-pubkey-fd specified, but no key available"),
-                enc_key => {
-                    CryptoParams {
-                        mode: CryptMode::Encrypt,
-                        enc_key,
-                        master_pubkey,
-                    }
-                },
-            },
-
-            // explicit keyfile, maybe default master key
-            (enc_key, None) => CryptoParams { mode: CryptMode::Encrypt, enc_key, master_pubkey: key::read_optional_default_master_pubkey()? },
-
-            // explicit keyfile and master key
-            (enc_key, master_pubkey) => CryptoParams { mode: CryptMode::Encrypt, enc_key, master_pubkey },
-        },
-
-        // explicitly disabled encryption
-        Some(CryptMode::None) => match (key, master_pubkey) {
-            // no keys => OK, no encryption
-            (None, None) => CryptoParams { mode: CryptMode::None, enc_key: None, master_pubkey: None },
-
-            // --keyfile and --crypt-mode=none
-            (Some(_), _) => bail!("--keyfile/--keyfd and --crypt-mode=none are mutually exclusive"),
-
-            // --master-pubkey-file and --crypt-mode=none
-            (_, Some(_)) => bail!("--master-pubkey-file/--master-pubkey-fd and --crypt-mode=none are mutually exclusive"),
-        },
-
-        // explicitly enabled encryption
-        Some(mode) => match (key, master_pubkey) {
-            // no key, maybe master key
-            (None, master_pubkey) => match key::read_optional_default_encryption_key()? {
-                None => bail!("--crypt-mode without --keyfile and no default key file available"),
-                enc_key => {
-                    eprintln!("Encrypting with default encryption key!");
-                    let master_pubkey = match master_pubkey {
-                        None => key::read_optional_default_master_pubkey()?,
-                        master_pubkey => master_pubkey,
-                    };
-
-                    CryptoParams {
-                        mode,
-                        enc_key,
-                        master_pubkey,
-                    }
-                },
-            },
-
-            // --keyfile and --crypt-mode other than none
-            (enc_key, master_pubkey) => {
-                let master_pubkey = match master_pubkey {
-                    None => key::read_optional_default_master_pubkey()?,
-                    master_pubkey => master_pubkey,
-                };
-
-                CryptoParams { mode, enc_key, master_pubkey }
-            },
-        },
-    };
-
-    Ok(res)
-}
-
-#[test]
-// WARNING: there must only be one test for crypto_parameters as the default key handling is not
-// safe w.r.t. concurrency
-fn test_crypto_parameters_handling() -> Result<(), Error> {
-    let some_key = vec![1;1];
-    let default_key = vec![2;1];
-
-    let some_master_key = vec![3;1];
-    let default_master_key = vec![4;1];
-
-    let keypath = "./target/testout/keyfile.test";
-    let master_keypath = "./target/testout/masterkeyfile.test";
-    let invalid_keypath = "./target/testout/invalid_keyfile.test";
-
-    let no_key_res = CryptoParams {
-        enc_key: None,
-        master_pubkey: None,
-        mode: CryptMode::None,
-    };
-    let some_key_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_path(
-            keypath.to_string(),
-            some_key.clone(),
-        )),
-        master_pubkey: None,
-        mode: CryptMode::Encrypt,
-    };
-    let some_key_some_master_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_path(
-            keypath.to_string(),
-            some_key.clone(),
-        )),
-        master_pubkey: Some(KeyWithSource::from_path(
-            master_keypath.to_string(),
-            some_master_key.clone(),
-        )),
-        mode: CryptMode::Encrypt,
-    };
-    let some_key_default_master_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_path(
-            keypath.to_string(),
-            some_key.clone(),
-        )),
-        master_pubkey: Some(KeyWithSource::from_default(default_master_key.clone())),
-        mode: CryptMode::Encrypt,
-    };
-
-    let some_key_sign_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_path(
-            keypath.to_string(),
-            some_key.clone(),
-        )),
-        master_pubkey: None,
-        mode: CryptMode::SignOnly,
-    };
-    let default_key_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_default(default_key.clone())),
-        master_pubkey: None,
-        mode: CryptMode::Encrypt,
-    };
-    let default_key_sign_res = CryptoParams {
-        enc_key: Some(KeyWithSource::from_default(default_key.clone())),
-        master_pubkey: None,
-        mode: CryptMode::SignOnly,
-    };
-
-    replace_file(&keypath, &some_key, CreateOptions::default())?;
-    replace_file(&master_keypath, &some_master_key, CreateOptions::default())?;
-
-    // no params, no default key == no key
-    let res = crypto_parameters(&json!({}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // keyfile param == key from keyfile
-    let res = crypto_parameters(&json!({"keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // crypt mode none == no key
-    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // crypt mode encrypt/sign-only, no keyfile, no default key == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
-
-    // crypt mode none with explicit key == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
-
-    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
-    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_sign_res);
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // invalid keyfile parameter always errors
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
-
-    // now set a default key
-    unsafe { key::set_test_encryption_key(Ok(Some(default_key.clone()))); }
-
-    // and repeat
-
-    // no params but default key == default key
-    let res = crypto_parameters(&json!({}));
-    assert_eq!(res.unwrap(), default_key_res);
-
-    // keyfile param == key from keyfile
-    let res = crypto_parameters(&json!({"keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // crypt mode none == no key
-    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // crypt mode encrypt/sign-only, no keyfile, default key == default key with correct mode
-    let res = crypto_parameters(&json!({"crypt-mode": "sign-only"}));
-    assert_eq!(res.unwrap(), default_key_sign_res);
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt"}));
-    assert_eq!(res.unwrap(), default_key_res);
-
-    // crypt mode none with explicit key == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
-
-    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
-    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_sign_res);
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // invalid keyfile parameter always errors
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
-
-    // now make default key retrieval error
-    unsafe { key::set_test_encryption_key(Err(format_err!("test error"))); }
-
-    // and repeat
-
-    // no params, default key retrieval errors == Error
-    assert!(crypto_parameters(&json!({})).is_err());
-
-    // keyfile param == key from keyfile
-    let res = crypto_parameters(&json!({"keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // crypt mode none == no key
-    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // crypt mode encrypt/sign-only, no keyfile, default key error == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
-
-    // crypt mode none with explicit key == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
-
-    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
-    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_sign_res);
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_res);
-
-    // invalid keyfile parameter always errors
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
-
-    // now remove default key again
-    unsafe { key::set_test_encryption_key(Ok(None)); }
-    // set a default master key
-    unsafe { key::set_test_default_master_pubkey(Ok(Some(default_master_key.clone()))); }
-
-    // and use an explicit master key
-    assert!(crypto_parameters(&json!({"master-pubkey-file": master_keypath})).is_err());
-    // just a default == no key
-    let res = crypto_parameters(&json!({}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // keyfile param == key from keyfile
-    let res = crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": master_keypath}));
-    assert_eq!(res.unwrap(), some_key_some_master_res);
-    // same with fallback to default master key
-    let res = crypto_parameters(&json!({"keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_default_master_res);
-
-    // crypt mode none == error
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "master-pubkey-file": master_keypath})).is_err());
-    // with just default master key == no key
-    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
-    assert_eq!(res.unwrap(), no_key_res);
-
-    // crypt mode encrypt without enc key == error
-    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt", "master-pubkey-file": master_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
-
-    // crypt mode none with explicit key == Error
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath, "master-pubkey-file": master_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
-
-    // crypt mode encrypt with keyfile == key from keyfile with correct mode
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath, "master-pubkey-file": master_keypath}));
-    assert_eq!(res.unwrap(), some_key_some_master_res);
-    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
-    assert_eq!(res.unwrap(), some_key_default_master_res);
-
-    // invalid master keyfile parameter always errors when a key is passed, even with a valid
-    // default master key
-    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "none"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "sign-only"})).is_err());
-    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "encrypt"})).is_err());
-
-    Ok(())
-}
-
 #[api(
    input: {
        properties: {
@@ -1164,7 +741,7 @@ async fn create_backup(
             );
 
             let (key, created, fingerprint) =
-                decrypt_key(&key_with_source.key, &key::get_encryption_key_password)?;
+                decrypt_key(&key_with_source.key, &get_encryption_key_password)?;
             println!("Encryption key fingerprint: {}", fingerprint);
 
             let crypt_config = CryptConfig::new(key)?;
@@ -1514,7 +1091,7 @@ async fn restore(param: Value) -> Result<Value, Error> {
         None => None,
         Some(ref key) => {
             let (key, _, _) =
-                decrypt_key(&key.key, &key::get_encryption_key_password).map_err(|err| {
+                decrypt_key(&key.key, &get_encryption_key_password).map_err(|err| {
                     eprintln!("{}", format_key_source(&key.source, "encryption"));
                     err
                 })?;
diff --git a/src/bin/proxmox_backup_client/benchmark.rs b/src/bin/proxmox_backup_client/benchmark.rs
index 1076dc19..c1673701 100644
--- a/src/bin/proxmox_backup_client/benchmark.rs
+++ b/src/bin/proxmox_backup_client/benchmark.rs
@@ -34,6 +34,8 @@ use crate::{
     connect,
 };
 
+use crate::proxmox_client_tools::key_source::get_encryption_key_password;
+
 #[api()]
 #[derive(Copy, Clone, Serialize)]
 /// Speed test result
@@ -152,7 +154,7 @@ pub async fn benchmark(
     let crypt_config = match keyfile {
         None => None,
         Some(path) => {
-            let (key, _, _) = load_and_decrypt_key(&path, &crate::key::get_encryption_key_password)?;
+            let (key, _, _) = load_and_decrypt_key(&path, &get_encryption_key_password)?;
             let crypt_config = CryptConfig::new(key)?;
             Some(Arc::new(crypt_config))
         }
diff --git a/src/bin/proxmox_backup_client/catalog.rs b/src/bin/proxmox_backup_client/catalog.rs
index 659200ff..f4b0a1d5 100644
--- a/src/bin/proxmox_backup_client/catalog.rs
+++ b/src/bin/proxmox_backup_client/catalog.rs
@@ -17,7 +17,6 @@ use crate::{
     extract_repository_from_value,
     format_key_source,
     record_repository,
-    key::get_encryption_key_password,
     decrypt_key,
     api_datastore_latest_snapshot,
     complete_repository,
@@ -38,6 +37,8 @@ use crate::{
     Shell,
 };
 
+use crate::proxmox_client_tools::key_source::get_encryption_key_password;
+
 #[api(
    input: {
         properties: {
diff --git a/src/bin/proxmox_backup_client/key.rs b/src/bin/proxmox_backup_client/key.rs
index 76b135a2..c442fad9 100644
--- a/src/bin/proxmox_backup_client/key.rs
+++ b/src/bin/proxmox_backup_client/key.rs
@@ -20,114 +20,10 @@ use proxmox_backup::{
     tools::paperkey::{generate_paper_key, PaperkeyFormat},
 };
 
-use crate::KeyWithSource;
-
-pub const DEFAULT_ENCRYPTION_KEY_FILE_NAME: &str = "encryption-key.json";
-pub const DEFAULT_MASTER_PUBKEY_FILE_NAME: &str = "master-public.pem";
-
-pub fn find_default_master_pubkey() -> Result<Option<PathBuf>, Error> {
-    super::find_xdg_file(
-        DEFAULT_MASTER_PUBKEY_FILE_NAME,
-        "default master public key file",
-    )
-}
-
-pub fn place_default_master_pubkey() -> Result<PathBuf, Error> {
-    super::place_xdg_file(
-        DEFAULT_MASTER_PUBKEY_FILE_NAME,
-        "default master public key file",
-    )
-}
-
-pub fn find_default_encryption_key() -> Result<Option<PathBuf>, Error> {
-    super::find_xdg_file(
-        DEFAULT_ENCRYPTION_KEY_FILE_NAME,
-        "default encryption key file",
-    )
-}
-
-pub fn place_default_encryption_key() -> Result<PathBuf, Error> {
-    super::place_xdg_file(
-        DEFAULT_ENCRYPTION_KEY_FILE_NAME,
-        "default encryption key file",
-    )
-}
-
-#[cfg(not(test))]
-pub(crate) fn read_optional_default_encryption_key() -> Result<Option<KeyWithSource>, Error> {
-    find_default_encryption_key()?
-        .map(|path| file_get_contents(path).map(KeyWithSource::from_default))
-        .transpose()
-}
-
-#[cfg(not(test))]
-pub(crate) fn read_optional_default_master_pubkey() -> Result<Option<KeyWithSource>, Error> {
-    find_default_master_pubkey()?
-        .map(|path| file_get_contents(path).map(KeyWithSource::from_default))
-        .transpose()
-}
-
-#[cfg(test)]
-static mut TEST_DEFAULT_ENCRYPTION_KEY: Result<Option<Vec<u8>>, Error> = Ok(None);
-
-#[cfg(test)]
-pub(crate) fn read_optional_default_encryption_key() -> Result<Option<KeyWithSource>, Error> {
-    // not safe when multiple concurrent test cases end up here!
-    unsafe {
-        match &TEST_DEFAULT_ENCRYPTION_KEY {
-            Ok(Some(key)) => Ok(Some(KeyWithSource::from_default(key.clone()))),
-            Ok(None) => Ok(None),
-            Err(_) => bail!("test error"),
-        }
-    }
-}
-
-#[cfg(test)]
-// not safe when multiple concurrent test cases end up here!
-pub(crate) unsafe fn set_test_encryption_key(value: Result<Option<Vec<u8>>, Error>) {
-    TEST_DEFAULT_ENCRYPTION_KEY = value;
-}
-
-#[cfg(test)]
-static mut TEST_DEFAULT_MASTER_PUBKEY: Result<Option<Vec<u8>>, Error> = Ok(None);
-
-#[cfg(test)]
-pub(crate) fn read_optional_default_master_pubkey() -> Result<Option<KeyWithSource>, Error> {
-    // not safe when multiple concurrent test cases end up here!
-    unsafe {
-        match &TEST_DEFAULT_MASTER_PUBKEY {
-            Ok(Some(key)) => Ok(Some(KeyWithSource::from_default(key.clone()))),
-            Ok(None) => Ok(None),
-            Err(_) => bail!("test error"),
-        }
-    }
-}
-
-#[cfg(test)]
-// not safe when multiple concurrent test cases end up here!
-pub(crate) unsafe fn set_test_default_master_pubkey(value: Result<Option<Vec<u8>>, Error>) {
-    TEST_DEFAULT_MASTER_PUBKEY = value;
-}
-
-pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
-    // fixme: implement other input methods
-
-    use std::env::VarError::*;
-    match std::env::var("PBS_ENCRYPTION_PASSWORD") {
-        Ok(p) => return Ok(p.as_bytes().to_vec()),
-        Err(NotUnicode(_)) => bail!("PBS_ENCRYPTION_PASSWORD contains bad characters"),
-        Err(NotPresent) => {
-            // Try another method
-        }
-    }
-
-    // If we're on a TTY, query the user for a password
-    if tty::stdin_isatty() {
-        return Ok(tty::read_password("Encryption Key Password: ")?);
-    }
-
-    bail!("no password input mechanism available");
-}
+use crate::proxmox_client_tools::key_source::{
+    find_default_encryption_key, find_default_master_pubkey, get_encryption_key_password,
+    place_default_encryption_key, place_default_master_pubkey,
+};
 
 #[api(
     input: {
diff --git a/src/bin/proxmox_backup_client/mod.rs b/src/bin/proxmox_backup_client/mod.rs
index a14b0dc1..d272dc8f 100644
--- a/src/bin/proxmox_backup_client/mod.rs
+++ b/src/bin/proxmox_backup_client/mod.rs
@@ -1,5 +1,3 @@
-use anyhow::{Context, Error};
-
 mod benchmark;
 pub use benchmark::*;
 mod mount;
@@ -13,29 +11,3 @@ pub use snapshot::*;
 
 pub mod key;
 
-pub fn base_directories() -> Result<xdg::BaseDirectories, Error> {
-    xdg::BaseDirectories::with_prefix("proxmox-backup").map_err(Error::from)
-}
-
-/// Convenience helper for better error messages:
-pub fn find_xdg_file(
-    file_name: impl AsRef<std::path::Path>,
-    description: &'static str,
-) -> Result<Option<std::path::PathBuf>, Error> {
-    let file_name = file_name.as_ref();
-    base_directories()
-        .map(|base| base.find_config_file(file_name))
-        .with_context(|| format!("error searching for {}", description))
-}
-
-pub fn place_xdg_file(
-    file_name: impl AsRef<std::path::Path>,
-    description: &'static str,
-) -> Result<std::path::PathBuf, Error> {
-    let file_name = file_name.as_ref();
-    base_directories()
-        .and_then(|base| {
-            base.place_config_file(file_name).map_err(Error::from)
-        })
-        .with_context(|| format!("failed to place {} in xdg home", description))
-}
diff --git a/src/bin/proxmox_backup_client/mount.rs b/src/bin/proxmox_backup_client/mount.rs
index be6aca05..f3498e35 100644
--- a/src/bin/proxmox_backup_client/mount.rs
+++ b/src/bin/proxmox_backup_client/mount.rs
@@ -43,6 +43,8 @@ use crate::{
     BufferedDynamicReadAt,
 };
 
+use crate::proxmox_client_tools::key_source::get_encryption_key_password;
+
 #[sortable]
 const API_METHOD_MOUNT: ApiMethod = ApiMethod::new(
     &ApiHandler::Sync(&mount),
@@ -182,7 +184,7 @@ async fn mount_do(param: Value, pipe: Option<Fd>) -> Result<Value, Error> {
         None => None,
         Some(path) => {
             println!("Encryption key file: '{:?}'", path);
-            let (key, _, fingerprint) = load_and_decrypt_key(&path, &crate::key::get_encryption_key_password)?;
+            let (key, _, fingerprint) = load_and_decrypt_key(&path, &get_encryption_key_password)?;
             println!("Encryption key fingerprint: '{}'", fingerprint);
             Some(Arc::new(CryptConfig::new(key)?))
         }
diff --git a/src/bin/proxmox_backup_client/snapshot.rs b/src/bin/proxmox_backup_client/snapshot.rs
index 5988ebf6..a98b1ca2 100644
--- a/src/bin/proxmox_backup_client/snapshot.rs
+++ b/src/bin/proxmox_backup_client/snapshot.rs
@@ -35,6 +35,8 @@ use crate::{
     record_repository,
 };
 
+use crate::proxmox_client_tools::key_source::get_encryption_key_password;
+
 #[api(
    input: {
         properties: {
@@ -239,7 +241,7 @@ async fn upload_log(param: Value) -> Result<Value, Error> {
     let crypt_config = match crypto.enc_key {
         None => None,
         Some(key) => {
-            let (key, _created, _) = decrypt_key(&key.key, &crate::key::get_encryption_key_password)?;
+            let (key, _created, _) = decrypt_key(&key.key, &get_encryption_key_password)?;
             let crypt_config = CryptConfig::new(key)?;
             Some(Arc::new(crypt_config))
         }
diff --git a/src/bin/proxmox_client_tools/key_source.rs b/src/bin/proxmox_client_tools/key_source.rs
new file mode 100644
index 00000000..92132ba5
--- /dev/null
+++ b/src/bin/proxmox_client_tools/key_source.rs
@@ -0,0 +1,573 @@
+use std::convert::TryFrom;
+use std::path::PathBuf;
+use std::os::unix::io::{FromRawFd, RawFd};
+use std::io::Read;
+
+use anyhow::{bail, format_err, Error};
+use serde_json::Value;
+
+use proxmox::api::schema::*;
+use proxmox::sys::linux::tty;
+use proxmox::tools::fs::file_get_contents;
+
+use proxmox_backup::backup::CryptMode;
+
+pub const DEFAULT_ENCRYPTION_KEY_FILE_NAME: &str = "encryption-key.json";
+pub const DEFAULT_MASTER_PUBKEY_FILE_NAME: &str = "master-public.pem";
+
+pub const KEYFILE_SCHEMA: Schema =
+    StringSchema::new("Path to encryption key. All data will be encrypted using this key.")
+        .schema();
+
+pub const KEYFD_SCHEMA: Schema =
+    IntegerSchema::new("Pass an encryption key via an already opened file descriptor.")
+        .minimum(0)
+        .schema();
+
+pub const MASTER_PUBKEY_FILE_SCHEMA: Schema = StringSchema::new(
+    "Path to master public key. The encryption key used for a backup will be encrypted using this key and appended to the backup.")
+    .schema();
+
+pub const MASTER_PUBKEY_FD_SCHEMA: Schema =
+    IntegerSchema::new("Pass a master public key via an already opened file descriptor.")
+        .minimum(0)
+        .schema();
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum KeySource {
+    DefaultKey,
+    Fd,
+    Path(String),
+}
+
+pub fn format_key_source(source: &KeySource, key_type: &str) -> String {
+    match source {
+        KeySource::DefaultKey => format!("Using default {} key..", key_type),
+        KeySource::Fd => format!("Using {} key from file descriptor..", key_type),
+        KeySource::Path(path) => format!("Using {} key from '{}'..", key_type, path),
+    }
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct KeyWithSource {
+    pub source: KeySource,
+    pub key: Vec<u8>,
+}
+
+impl KeyWithSource {
+    pub fn from_fd(key: Vec<u8>) -> Self {
+        Self {
+            source: KeySource::Fd,
+            key,
+        }
+    }
+
+    pub fn from_default(key: Vec<u8>) -> Self {
+        Self {
+            source: KeySource::DefaultKey,
+            key,
+        }
+    }
+
+    pub fn from_path(path: String, key: Vec<u8>) -> Self {
+        Self {
+            source: KeySource::Path(path),
+            key,
+        }
+    }
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct CryptoParams {
+    pub mode: CryptMode,
+    pub enc_key: Option<KeyWithSource>,
+    // FIXME switch to openssl::rsa::rsa<openssl::pkey::Public> once that is Eq?
+    pub master_pubkey: Option<KeyWithSource>,
+}
+
+pub fn crypto_parameters(param: &Value) -> Result<CryptoParams, Error> {
+    let keyfile = match param.get("keyfile") {
+        Some(Value::String(keyfile)) => Some(keyfile),
+        Some(_) => bail!("bad --keyfile parameter type"),
+        None => None,
+    };
+
+    let key_fd = match param.get("keyfd") {
+        Some(Value::Number(key_fd)) => Some(
+            RawFd::try_from(key_fd
+                .as_i64()
+                .ok_or_else(|| format_err!("bad key fd: {:?}", key_fd))?
+            )
+            .map_err(|err| format_err!("bad key fd: {:?}: {}", key_fd, err))?
+        ),
+        Some(_) => bail!("bad --keyfd parameter type"),
+        None => None,
+    };
+
+    let master_pubkey_file = match param.get("master-pubkey-file") {
+        Some(Value::String(keyfile)) => Some(keyfile),
+        Some(_) => bail!("bad --master-pubkey-file parameter type"),
+        None => None,
+    };
+
+    let master_pubkey_fd = match param.get("master-pubkey-fd") {
+        Some(Value::Number(key_fd)) => Some(
+            RawFd::try_from(key_fd
+                .as_i64()
+                .ok_or_else(|| format_err!("bad master public key fd: {:?}", key_fd))?
+            )
+            .map_err(|err| format_err!("bad public master key fd: {:?}: {}", key_fd, err))?
+        ),
+        Some(_) => bail!("bad --master-pubkey-fd parameter type"),
+        None => None,
+    };
+
+    let mode: Option<CryptMode> = match param.get("crypt-mode") {
+        Some(mode) => Some(serde_json::from_value(mode.clone())?),
+        None => None,
+    };
+
+    let key = match (keyfile, key_fd) {
+        (None, None) => None,
+        (Some(_), Some(_)) => bail!("--keyfile and --keyfd are mutually exclusive"),
+        (Some(keyfile), None) => Some(KeyWithSource::from_path(
+            keyfile.clone(),
+            file_get_contents(keyfile)?,
+        )),
+        (None, Some(fd)) => {
+            let input = unsafe { std::fs::File::from_raw_fd(fd) };
+            let mut data = Vec::new();
+            let _len: usize = { input }.read_to_end(&mut data).map_err(|err| {
+                format_err!("error reading encryption key from fd {}: {}", fd, err)
+            })?;
+            Some(KeyWithSource::from_fd(data))
+        }
+    };
+
+    let master_pubkey = match (master_pubkey_file, master_pubkey_fd) {
+        (None, None) => None,
+        (Some(_), Some(_)) => bail!("--keyfile and --keyfd are mutually exclusive"),
+        (Some(keyfile), None) => Some(KeyWithSource::from_path(
+            keyfile.clone(),
+            file_get_contents(keyfile)?,
+        )),
+        (None, Some(fd)) => {
+            let input = unsafe { std::fs::File::from_raw_fd(fd) };
+            let mut data = Vec::new();
+            let _len: usize = { input }
+                .read_to_end(&mut data)
+                .map_err(|err| format_err!("error reading master key from fd {}: {}", fd, err))?;
+            Some(KeyWithSource::from_fd(data))
+        }
+    };
+
+    let res = match mode {
+        // no crypt mode, enable encryption if keys are available
+        None => match (key, master_pubkey) {
+            // only default keys if available
+            (None, None) => match read_optional_default_encryption_key()? {
+                None => CryptoParams { mode: CryptMode::None, enc_key: None, master_pubkey: None },
+                enc_key => {
+                    let master_pubkey = read_optional_default_master_pubkey()?;
+                    CryptoParams {
+                        mode: CryptMode::Encrypt,
+                        enc_key,
+                        master_pubkey,
+                    }
+                },
+            },
+
+            // explicit master key, default enc key needed
+            (None, master_pubkey) => match read_optional_default_encryption_key()? {
+                None => bail!("--master-pubkey-file/--master-pubkey-fd specified, but no key available"),
+                enc_key => {
+                    CryptoParams {
+                        mode: CryptMode::Encrypt,
+                        enc_key,
+                        master_pubkey,
+                    }
+                },
+            },
+
+            // explicit keyfile, maybe default master key
+            (enc_key, None) => CryptoParams { mode: CryptMode::Encrypt, enc_key, master_pubkey: read_optional_default_master_pubkey()? },
+
+            // explicit keyfile and master key
+            (enc_key, master_pubkey) => CryptoParams { mode: CryptMode::Encrypt, enc_key, master_pubkey },
+        },
+
+        // explicitly disabled encryption
+        Some(CryptMode::None) => match (key, master_pubkey) {
+            // no keys => OK, no encryption
+            (None, None) => CryptoParams { mode: CryptMode::None, enc_key: None, master_pubkey: None },
+
+            // --keyfile and --crypt-mode=none
+            (Some(_), _) => bail!("--keyfile/--keyfd and --crypt-mode=none are mutually exclusive"),
+
+            // --master-pubkey-file and --crypt-mode=none
+            (_, Some(_)) => bail!("--master-pubkey-file/--master-pubkey-fd and --crypt-mode=none are mutually exclusive"),
+        },
+
+        // explicitly enabled encryption
+        Some(mode) => match (key, master_pubkey) {
+            // no key, maybe master key
+            (None, master_pubkey) => match read_optional_default_encryption_key()? {
+                None => bail!("--crypt-mode without --keyfile and no default key file available"),
+                enc_key => {
+                    eprintln!("Encrypting with default encryption key!");
+                    let master_pubkey = match master_pubkey {
+                        None => read_optional_default_master_pubkey()?,
+                        master_pubkey => master_pubkey,
+                    };
+
+                    CryptoParams {
+                        mode,
+                        enc_key,
+                        master_pubkey,
+                    }
+                },
+            },
+
+            // --keyfile and --crypt-mode other than none
+            (enc_key, master_pubkey) => {
+                let master_pubkey = match master_pubkey {
+                    None => read_optional_default_master_pubkey()?,
+                    master_pubkey => master_pubkey,
+                };
+
+                CryptoParams { mode, enc_key, master_pubkey }
+            },
+        },
+    };
+
+    Ok(res)
+}
+
+pub fn find_default_master_pubkey() -> Result<Option<PathBuf>, Error> {
+    super::find_xdg_file(
+        DEFAULT_MASTER_PUBKEY_FILE_NAME,
+        "default master public key file",
+    )
+}
+
+pub fn place_default_master_pubkey() -> Result<PathBuf, Error> {
+    super::place_xdg_file(
+        DEFAULT_MASTER_PUBKEY_FILE_NAME,
+        "default master public key file",
+    )
+}
+
+pub fn find_default_encryption_key() -> Result<Option<PathBuf>, Error> {
+    super::find_xdg_file(
+        DEFAULT_ENCRYPTION_KEY_FILE_NAME,
+        "default encryption key file",
+    )
+}
+
+pub fn place_default_encryption_key() -> Result<PathBuf, Error> {
+    super::place_xdg_file(
+        DEFAULT_ENCRYPTION_KEY_FILE_NAME,
+        "default encryption key file",
+    )
+}
+
+#[cfg(not(test))]
+pub(crate) fn read_optional_default_encryption_key() -> Result<Option<KeyWithSource>, Error> {
+    find_default_encryption_key()?
+        .map(|path| file_get_contents(path).map(KeyWithSource::from_default))
+        .transpose()
+}
+
+#[cfg(not(test))]
+pub(crate) fn read_optional_default_master_pubkey() -> Result<Option<KeyWithSource>, Error> {
+    find_default_master_pubkey()?
+        .map(|path| file_get_contents(path).map(KeyWithSource::from_default))
+        .transpose()
+}
+
+#[cfg(test)]
+static mut TEST_DEFAULT_ENCRYPTION_KEY: Result<Option<Vec<u8>>, Error> = Ok(None);
+
+#[cfg(test)]
+pub(crate) fn read_optional_default_encryption_key() -> Result<Option<KeyWithSource>, Error> {
+    // not safe when multiple concurrent test cases end up here!
+    unsafe {
+        match &TEST_DEFAULT_ENCRYPTION_KEY {
+            Ok(Some(key)) => Ok(Some(KeyWithSource::from_default(key.clone()))),
+            Ok(None) => Ok(None),
+            Err(_) => bail!("test error"),
+        }
+    }
+}
+
+#[cfg(test)]
+// not safe when multiple concurrent test cases end up here!
+pub(crate) unsafe fn set_test_encryption_key(value: Result<Option<Vec<u8>>, Error>) {
+    TEST_DEFAULT_ENCRYPTION_KEY = value;
+}
+
+#[cfg(test)]
+static mut TEST_DEFAULT_MASTER_PUBKEY: Result<Option<Vec<u8>>, Error> = Ok(None);
+
+#[cfg(test)]
+pub(crate) fn read_optional_default_master_pubkey() -> Result<Option<KeyWithSource>, Error> {
+    // not safe when multiple concurrent test cases end up here!
+    unsafe {
+        match &TEST_DEFAULT_MASTER_PUBKEY {
+            Ok(Some(key)) => Ok(Some(KeyWithSource::from_default(key.clone()))),
+            Ok(None) => Ok(None),
+            Err(_) => bail!("test error"),
+        }
+    }
+}
+
+#[cfg(test)]
+// not safe when multiple concurrent test cases end up here!
+pub(crate) unsafe fn set_test_default_master_pubkey(value: Result<Option<Vec<u8>>, Error>) {
+    TEST_DEFAULT_MASTER_PUBKEY = value;
+}
+
+pub fn get_encryption_key_password() -> Result<Vec<u8>, Error> {
+    // fixme: implement other input methods
+
+    use std::env::VarError::*;
+    match std::env::var("PBS_ENCRYPTION_PASSWORD") {
+        Ok(p) => return Ok(p.as_bytes().to_vec()),
+        Err(NotUnicode(_)) => bail!("PBS_ENCRYPTION_PASSWORD contains bad characters"),
+        Err(NotPresent) => {
+            // Try another method
+        }
+    }
+
+    // If we're on a TTY, query the user for a password
+    if tty::stdin_isatty() {
+        return Ok(tty::read_password("Encryption Key Password: ")?);
+    }
+
+    bail!("no password input mechanism available");
+}
+
+#[test]
+// WARNING: there must only be one test for crypto_parameters as the default key handling is not
+// safe w.r.t. concurrency
+fn test_crypto_parameters_handling() -> Result<(), Error> {
+    use serde_json::json;
+    use proxmox::tools::fs::{replace_file, CreateOptions};
+
+    let some_key = vec![1;1];
+    let default_key = vec![2;1];
+
+    let some_master_key = vec![3;1];
+    let default_master_key = vec![4;1];
+
+    let keypath = "./target/testout/keyfile.test";
+    let master_keypath = "./target/testout/masterkeyfile.test";
+    let invalid_keypath = "./target/testout/invalid_keyfile.test";
+
+    let no_key_res = CryptoParams {
+        enc_key: None,
+        master_pubkey: None,
+        mode: CryptMode::None,
+    };
+    let some_key_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_path(
+            keypath.to_string(),
+            some_key.clone(),
+        )),
+        master_pubkey: None,
+        mode: CryptMode::Encrypt,
+    };
+    let some_key_some_master_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_path(
+            keypath.to_string(),
+            some_key.clone(),
+        )),
+        master_pubkey: Some(KeyWithSource::from_path(
+            master_keypath.to_string(),
+            some_master_key.clone(),
+        )),
+        mode: CryptMode::Encrypt,
+    };
+    let some_key_default_master_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_path(
+            keypath.to_string(),
+            some_key.clone(),
+        )),
+        master_pubkey: Some(KeyWithSource::from_default(default_master_key.clone())),
+        mode: CryptMode::Encrypt,
+    };
+
+    let some_key_sign_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_path(
+            keypath.to_string(),
+            some_key.clone(),
+        )),
+        master_pubkey: None,
+        mode: CryptMode::SignOnly,
+    };
+    let default_key_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_default(default_key.clone())),
+        master_pubkey: None,
+        mode: CryptMode::Encrypt,
+    };
+    let default_key_sign_res = CryptoParams {
+        enc_key: Some(KeyWithSource::from_default(default_key.clone())),
+        master_pubkey: None,
+        mode: CryptMode::SignOnly,
+    };
+
+    replace_file(&keypath, &some_key, CreateOptions::default())?;
+    replace_file(&master_keypath, &some_master_key, CreateOptions::default())?;
+
+    // no params, no default key == no key
+    let res = crypto_parameters(&json!({}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // keyfile param == key from keyfile
+    let res = crypto_parameters(&json!({"keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // crypt mode none == no key
+    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // crypt mode encrypt/sign-only, no keyfile, no default key == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
+
+    // crypt mode none with explicit key == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
+
+    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
+    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_sign_res);
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // invalid keyfile parameter always errors
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
+
+    // now set a default key
+    unsafe { set_test_encryption_key(Ok(Some(default_key.clone()))); }
+
+    // and repeat
+
+    // no params but default key == default key
+    let res = crypto_parameters(&json!({}));
+    assert_eq!(res.unwrap(), default_key_res);
+
+    // keyfile param == key from keyfile
+    let res = crypto_parameters(&json!({"keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // crypt mode none == no key
+    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // crypt mode encrypt/sign-only, no keyfile, default key == default key with correct mode
+    let res = crypto_parameters(&json!({"crypt-mode": "sign-only"}));
+    assert_eq!(res.unwrap(), default_key_sign_res);
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt"}));
+    assert_eq!(res.unwrap(), default_key_res);
+
+    // crypt mode none with explicit key == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
+
+    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
+    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_sign_res);
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // invalid keyfile parameter always errors
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
+
+    // now make default key retrieval error
+    unsafe { set_test_encryption_key(Err(format_err!("test error"))); }
+
+    // and repeat
+
+    // no params, default key retrieval errors == Error
+    assert!(crypto_parameters(&json!({})).is_err());
+
+    // keyfile param == key from keyfile
+    let res = crypto_parameters(&json!({"keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // crypt mode none == no key
+    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // crypt mode encrypt/sign-only, no keyfile, default key error == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
+
+    // crypt mode none with explicit key == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
+
+    // crypt mode sign-only/encrypt with keyfile == key from keyfile with correct mode
+    let res = crypto_parameters(&json!({"crypt-mode": "sign-only", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_sign_res);
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_res);
+
+    // invalid keyfile parameter always errors
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "none"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": invalid_keypath, "crypt-mode": "encrypt"})).is_err());
+
+    // now remove default key again
+    unsafe { set_test_encryption_key(Ok(None)); }
+    // set a default master key
+    unsafe { set_test_default_master_pubkey(Ok(Some(default_master_key.clone()))); }
+
+    // and use an explicit master key
+    assert!(crypto_parameters(&json!({"master-pubkey-file": master_keypath})).is_err());
+    // just a default == no key
+    let res = crypto_parameters(&json!({}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // keyfile param == key from keyfile
+    let res = crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": master_keypath}));
+    assert_eq!(res.unwrap(), some_key_some_master_res);
+    // same with fallback to default master key
+    let res = crypto_parameters(&json!({"keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_default_master_res);
+
+    // crypt mode none == error
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "master-pubkey-file": master_keypath})).is_err());
+    // with just default master key == no key
+    let res = crypto_parameters(&json!({"crypt-mode": "none"}));
+    assert_eq!(res.unwrap(), no_key_res);
+
+    // crypt mode encrypt without enc key == error
+    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt", "master-pubkey-file": master_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"crypt-mode": "encrypt"})).is_err());
+
+    // crypt mode none with explicit key == Error
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath, "master-pubkey-file": master_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"crypt-mode": "none", "keyfile": keypath})).is_err());
+
+    // crypt mode encrypt with keyfile == key from keyfile with correct mode
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath, "master-pubkey-file": master_keypath}));
+    assert_eq!(res.unwrap(), some_key_some_master_res);
+    let res = crypto_parameters(&json!({"crypt-mode": "encrypt", "keyfile": keypath}));
+    assert_eq!(res.unwrap(), some_key_default_master_res);
+
+    // invalid master keyfile parameter always errors when a key is passed, even with a valid
+    // default master key
+    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "none"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "sign-only"})).is_err());
+    assert!(crypto_parameters(&json!({"keyfile": keypath, "master-pubkey-file": invalid_keypath,"crypt-mode": "encrypt"})).is_err());
+
+    Ok(())
+}
+
diff --git a/src/bin/proxmox_client_tools/mod.rs b/src/bin/proxmox_client_tools/mod.rs
index 7b69e8cb..73744ba2 100644
--- a/src/bin/proxmox_client_tools/mod.rs
+++ b/src/bin/proxmox_client_tools/mod.rs
@@ -1,8 +1,7 @@
 //! Shared tools useful for common CLI clients.
-
 use std::collections::HashMap;
 
-use anyhow::{bail, format_err, Error};
+use anyhow::{bail, format_err, Context, Error};
 use serde_json::{json, Value};
 use xdg::BaseDirectories;
 
@@ -17,6 +16,8 @@ use proxmox_backup::backup::BackupDir;
 use proxmox_backup::client::*;
 use proxmox_backup::tools;
 
+pub mod key_source;
+
 const ENV_VAR_PBS_FINGERPRINT: &str = "PBS_FINGERPRINT";
 const ENV_VAR_PBS_PASSWORD: &str = "PBS_PASSWORD";
 
@@ -25,24 +26,6 @@ pub const REPO_URL_SCHEMA: Schema = StringSchema::new("Repository URL.")
     .max_length(256)
     .schema();
 
-pub const KEYFILE_SCHEMA: Schema =
-    StringSchema::new("Path to encryption key. All data will be encrypted using this key.")
-        .schema();
-
-pub const KEYFD_SCHEMA: Schema =
-    IntegerSchema::new("Pass an encryption key via an already opened file descriptor.")
-        .minimum(0)
-        .schema();
-
-pub const MASTER_PUBKEY_FILE_SCHEMA: Schema = StringSchema::new(
-    "Path to master public key. The encryption key used for a backup will be encrypted using this key and appended to the backup.")
-    .schema();
-
-pub const MASTER_PUBKEY_FD_SCHEMA: Schema =
-    IntegerSchema::new("Pass a master public key via an already opened file descriptor.")
-        .minimum(0)
-        .schema();
-
 pub const CHUNK_SIZE_SCHEMA: Schema = IntegerSchema::new("Chunk size in KB. Must be a power of 2.")
     .minimum(64)
     .maximum(4096)
@@ -364,3 +347,28 @@ pub fn complete_backup_source(arg: &str, param: &HashMap<String, String>) -> Vec
 
     result
 }
+
+pub fn base_directories() -> Result<xdg::BaseDirectories, Error> {
+    xdg::BaseDirectories::with_prefix("proxmox-backup").map_err(Error::from)
+}
+
+/// Convenience helper for better error messages:
+pub fn find_xdg_file(
+    file_name: impl AsRef<std::path::Path>,
+    description: &'static str,
+) -> Result<Option<std::path::PathBuf>, Error> {
+    let file_name = file_name.as_ref();
+    base_directories()
+        .map(|base| base.find_config_file(file_name))
+        .with_context(|| format!("error searching for {}", description))
+}
+
+pub fn place_xdg_file(
+    file_name: impl AsRef<std::path::Path>,
+    description: &'static str,
+) -> Result<std::path::PathBuf, Error> {
+    let file_name = file_name.as_ref();
+    base_directories()
+        .and_then(|base| base.place_config_file(file_name).map_err(Error::from))
+        .with_context(|| format!("failed to place {} in xdg home", description))
+}
-- 
2.20.1