From 967750cecfeacdcecce87bbf63ac25aa38351144 Mon Sep 17 00:00:00 2001 From: Jack Grigg Date: Sun, 17 Dec 2023 17:23:11 +0000 Subject: [PATCH] scrypt: Increase `log_n` until it is measurable Closes str4d/rage#418. --- age/CHANGELOG.md | 2 ++ age/src/scrypt.rs | 15 +++++++++++---- 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/age/CHANGELOG.md b/age/CHANGELOG.md index e7059f3..18363b4 100644 --- a/age/CHANGELOG.md +++ b/age/CHANGELOG.md @@ -17,6 +17,8 @@ to 1.0.0 are beta releases. - Migrated to `base64 0.21`, `rsa 0.9`. ### Fixed +- `age::Encryptor::with_user_passphrase` will now re-measure the `scrypt` work + factor until it is measurable, instead of setting the work factor to maximum. - `age::cli_common`: - `UiCallbacks::confirm` no longer requires erasing the confirmation message before it will accept a response. diff --git a/age/src/scrypt.rs b/age/src/scrypt.rs index f2416ee..6f254f3 100644 --- a/age/src/scrypt.rs +++ b/age/src/scrypt.rs @@ -25,10 +25,7 @@ const ENCRYPTED_FILE_KEY_BYTES: usize = FILE_KEY_BYTES + 16; /// /// Guaranteed to return a valid work factor (less than 64). fn target_scrypt_work_factor() -> u8 { - // Time a work factor that should always be fast. - let mut log_n = 10; - - let duration: Option = { + let measure_duration = |log_n| { // Platforms that have a functional SystemTime::now(): #[cfg(not(all(target_arch = "wasm32", not(target_os = "wasi"))))] { @@ -61,6 +58,16 @@ fn target_scrypt_work_factor() -> u8 { } }; + // Time a work factor that should always be fast. + let mut log_n = 10; + let mut duration: Option = measure_duration(log_n); + while duration.map(|d| d.is_zero()).unwrap_or(false) { + // On some newer platforms, the work factor may be so fast that it is cannot be + // measured. Increase the work factor until we can measure something. + log_n += 1; + duration = measure_duration(log_n); + } + duration .map(|mut d| { // Use duration as a proxy for CPU usage, which scales linearly with N.