From fb788083d456e24593aa62431f7f377bb793daf4 Mon Sep 17 00:00:00 2001
From: Arthur Gautier <arthur.gautier@arista.com>
Date: Mon, 17 Jun 2024 23:09:02 -0700
Subject: [PATCH] oaep: fixup `Deserialize` implementation

label_data was always empty because it was consumed by data.

This commits re-splits the payload according to the selected mgf hash.
---
 Cargo.lock               |  1 +
 Cargo.toml               |  5 ++--
 src/rsa/oaep/commands.rs | 50 ++++++++++++++++++++++++++++++++++++++--
 3 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f41f2698..4c6651df 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1024,6 +1024,7 @@ dependencies = [
  "rusb",
  "serde",
  "serde_json",
+ "sha1",
  "sha2",
  "signature",
  "spki",
diff --git a/Cargo.toml b/Cargo.toml
index 797c7b2a..03a87313 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,6 +22,7 @@ bitflags = "2"
 cmac = "0.7"
 cbc = "0.1"
 ccm = { version = "0.5", features = ["std"] }
+digest = { version = "0.10", default-features = false }
 ecdsa = { version = "0.16", default-features = false, features = ["pkcs8"] }
 ed25519 = "2"
 log = "0.4"
@@ -41,12 +42,12 @@ uuid = { version = "1", default-features = false }
 zeroize = { version = "1", features = ["zeroize_derive"] }
 
 # optional dependencies
-digest = { version = "0.10", optional = true, default-features = false }
 ed25519-dalek = { version = "2", optional = true, features = ["rand_core"] }
 hmac = { version = "0.12", optional = true }
 k256 = { version = "0.13", optional = true, features = ["ecdsa", "sha256"] }
 pbkdf2 = { version = "0.12", optional = true, default-features = false, features = ["hmac"] }
 serde_json = { version = "1", optional = true }
+sha1 = { version = "0.10", optional = true }
 rusb = { version = "0.9", optional = true }
 tiny_http = { version = "0.12", optional = true }
 
@@ -60,7 +61,7 @@ x509-cert = { version = "0.2.5", features = ["builder"] }
 default = ["http", "passwords", "setup"]
 http-server = ["tiny_http"]
 http = []
-mockhsm = ["digest", "ecdsa/arithmetic", "ed25519-dalek", "p256/ecdsa", "secp256k1"]
+mockhsm = ["ecdsa/arithmetic", "ed25519-dalek", "p256/ecdsa", "secp256k1", "sha1"]
 passwords = ["hmac", "pbkdf2"]
 secp256k1 = ["k256"]
 setup = ["passwords", "serde_json", "uuid/serde"]
diff --git a/src/rsa/oaep/commands.rs b/src/rsa/oaep/commands.rs
index c58f39e4..df6b4bb5 100644
--- a/src/rsa/oaep/commands.rs
+++ b/src/rsa/oaep/commands.rs
@@ -6,10 +6,13 @@ use crate::{
     response::Response,
     rsa,
 };
-use serde::{Deserialize, Serialize};
+use digest::{typenum::Unsigned, OutputSizeUser};
+use serde::{de::Deserializer, Deserialize, Serialize};
+use sha1::Sha1;
+use sha2::{Sha256, Sha384, Sha512};
 
 /// Request parameters for `command::decrypt_rsa_oaep`
-#[derive(Serialize, Deserialize, Debug)]
+#[derive(Serialize, Debug)]
 pub(crate) struct DecryptOaepCommand {
     /// ID of the decryption key
     pub key_id: object::Id,
@@ -41,3 +44,46 @@ impl From<DecryptOaepResponse> for rsa::oaep::DecryptedData {
         response.0
     }
 }
+
+impl<'de> Deserialize<'de> for DecryptOaepCommand {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        #[derive(Deserialize)]
+        struct DecryptOaepCommand {
+            /// ID of the decryption key
+            key_id: object::Id,
+
+            /// Hash algorithm to use for MGF1
+            mgf1_hash_alg: rsa::mgf::Algorithm,
+
+            /// Data to be decrypted
+            data: Vec<u8>,
+        }
+
+        let mut value = DecryptOaepCommand::deserialize(deserializer)?;
+
+        let label_hash = match value.mgf1_hash_alg {
+            rsa::mgf::Algorithm::Sha1 => value
+                .data
+                .split_off(value.data.len() - <Sha1 as OutputSizeUser>::OutputSize::USIZE),
+            rsa::mgf::Algorithm::Sha256 => value
+                .data
+                .split_off(value.data.len() - <Sha256 as OutputSizeUser>::OutputSize::USIZE),
+            rsa::mgf::Algorithm::Sha384 => value
+                .data
+                .split_off(value.data.len() - <Sha384 as OutputSizeUser>::OutputSize::USIZE),
+            rsa::mgf::Algorithm::Sha512 => value
+                .data
+                .split_off(value.data.len() - <Sha512 as OutputSizeUser>::OutputSize::USIZE),
+        };
+
+        Ok(Self {
+            key_id: value.key_id,
+            mgf1_hash_alg: value.mgf1_hash_alg,
+            data: value.data,
+            label_hash,
+        })
+    }
+}