Backport 25969 ([opentitantool] Correct the SHA256 hash ordering)

rules/signing.bzl

@@ -275,13 +275,13 @@ def _presigning_artifacts(ctx, opentitantool, src, manifest, ecdsa_key, rsa_key,
     if spx_key:
         if spx_domain.lower() == "prehashedsha256":
             spxmsg = digest
+            rev = spx_key.config.get("byte-reversal-bug", "false")
+            fmt = "Sha256HashReversed" if rev == "true" else "Sha256Hash"
             signing_directives.append(struct(
                 command = "spx-sign",
                 id = None,
                 label = spx_key.name,
-                # TODO(#25870): Set `little_endian` appropriately.
-                little_endian = True,
-                format = "Sha256Hash",
+                format = fmt,
                 domain = spx_domain,
                 output = "{}.spx_sig".format(basename),
                 input = "{}.digest".format(basename),
@@ -306,7 +306,6 @@ def _presigning_artifacts(ctx, opentitantool, src, manifest, ecdsa_key, rsa_key,
                 command = "spx-sign",
                 id = None,
                 label = spx_key.name,
-                little_endian = False,
                 format = "PlainText",
                 domain = spx_domain,
                 output = "{}.spx_sig".format(basename),
@@ -375,15 +374,7 @@ def _local_sign(ctx, tool, digest, ecdsa_key, rsa_key, spxmsg = None, spx_key =
             fail("Expected either KeyInfo or KeySetInfo; got neither")
         spx_sig = ctx.actions.declare_file(paths.replace_extension(spxmsg.basename, ".spx_sig"))
         domain = spx_key.config.get("domain", "Pure")
-
-        # TODO(#25870): Currently, opentitantool emits SHA256 digests in byte-reversed order,
-        # so for proper creation of PrehashedSha256 signatures, we need to reverse the input.
-        # The ROM erroneously uses the reversed representation, so when "byte-reversal-bug" is
-        # true, we should not reverse the bytes (since they're already reversed).
-        # This logic will change when we fix opentitantool to emit in the correct order.
-        rev = "true" if domain.lower() == "prehashedsha256" else "false"
-        if spx_key.config.get("byte-reversal-bug") == "true":
-            rev = "false"
+        rev = spx_key.config.get("byte-reversal-bug", "false")
         ctx.actions.run(
             outputs = [spx_sig],
             inputs = [spxmsg, private_key],
@@ -392,7 +383,7 @@ def _local_sign(ctx, tool, digest, ecdsa_key, rsa_key, spxmsg = None, spx_key =
                 "--quiet",
                 "spx",
                 "sign",
-                "--input-bytes-reversed={}".format(rev),
+                "--spx-hash-reversal-bug={}".format(rev),
                 "--domain={}".format(domain),
                 "--output={}".format(spx_sig.path),
                 spxmsg.path,
@@ -469,10 +460,11 @@ def _hsmtool_sign(ctx, tool, digest, ecdsa_key, rsa_key, spxmsg = None, spx_key
     if spxmsg and spx_key:
         domain = spx_key.config.get("domain", "Pure")
         if domain.lower() == "prehashedsha256":
+            rev = spx_key.config.get("byte-reversal-bug", "false")
+            fmt = "sha256-hash-reversed" if rev == "true" else "sha256-hash"
             args = [
-                # TODO(#25870): Set `little-endian` appropriately.
                 "--little-endian",
-                "--format=sha256-hash",
+                "--format={}".format(fmt),
                 "--domain={}".format(domain),
             ]
         else:

signing/softhsm/README.md

@@ -11,3 +11,22 @@ softhsm2-util --init-token --label fake_keys --so-pin officer_pin --pin 123456 -
 ```
 
 Where `softhsm-util` is one of the binaries emitted by the `@softhsm2//:softhsm2` target.
+
+## Keys
+
+The softhsm instance contains a few keys needed for testing.  These were
+imported with hsmtool.
+
+```
+export HSMTOOL_MODULE=bazel-out/k8-fastbuild/bin/external/softhsm2/softhsm2/lib/softhsm/libsofthsm2.so
+export HSMTOOL_SPX_MODULE=pkcs11-ef
+export SOFTHSM2_CONF=signing/softhsm/softhsm.conf
+
+hsmtool -t fake_keys -u user -p 123456 \
+    ecdsa import --label fake_app_prod_ecdsa \
+    sw/device/silicon_creator/lib/ownership/keys/fake/app_prod_ecdsa_p256.der
+
+hsmtool -t fake_keys -u user -p 123456 \
+    spx import --label fake_app_prod_spx \
+    sw/device/silicon_creator/lib/ownership/keys/fake/app_prod_spx.pem
+```

sw/device/silicon_creator/lib/ownership/keys/fake/BUILD

@@ -80,6 +80,16 @@ filegroup(
     srcs = ["app_dev_ecdsa_p256.pub.der"],
 )
 
+filegroup(
+    name = "app_spx_prod",
+    srcs = ["app_prod_spx.pem"],
+)
+
+filegroup(
+    name = "app_spx_prod_pub",
+    srcs = ["app_prod_spx.pub.pem"],
+)
+
 key_ecdsa(
     name = "app_prod_ecdsa",
     method = "local",

sw/host/hsmtool/src/commands/ecdsa/sign.rs

@@ -25,7 +25,7 @@ pub struct Sign {
     label: Option<String>,
     #[arg(short, long, default_value = "sha256-hash", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data and result (for little-endian targets).
+    /// Reverse the result (for little-endian targets).
     #[arg(short = 'r', long)]
     little_endian: bool,
     #[arg(short, long)]
@@ -51,9 +51,8 @@ impl Dispatch for Sign {
         let object = helper::find_one_object(session, &attrs)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .prepare(KeyType::Ec, &data, self.little_endian)?;
+        let data = self.format.prepare(KeyType::Ec, &data)?;
+
         let mechanism = self.format.mechanism(KeyType::Ec)?;
         let mut result = session.sign(&mechanism, object, &data)?;
         if self.little_endian {

sw/host/hsmtool/src/commands/ecdsa/verify.rs

@@ -25,7 +25,7 @@ pub struct Verify {
     label: Option<String>,
     #[arg(short, long, default_value = "sha256-hash", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data and result (for little-endian targets).
+    /// Reverse the result (for little-endian targets).
     #[arg(short = 'r', long)]
     little_endian: bool,
     /// The signature is at the given byte range of the input file.
@@ -51,9 +51,7 @@ impl Dispatch for Verify {
         let object = helper::find_one_object(session, &attrs)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .prepare(KeyType::Ec, &data, self.little_endian)?;
+        let data = self.format.prepare(KeyType::Ec, &data)?;
         let mechanism = self.format.mechanism(KeyType::Ec)?;
         let mut signature = if let Some(filename) = &self.signature {
             std::fs::read(filename)?

sw/host/hsmtool/src/commands/rsa/sign.rs

@@ -25,7 +25,7 @@ pub struct Sign {
     label: Option<String>,
     #[arg(short, long, default_value = "sha256-hash", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data and result (for little-endian targets).
+    /// Reverse the result (for little-endian targets).
     #[arg(short = 'r', long)]
     little_endian: bool,
     #[arg(short, long)]
@@ -51,9 +51,7 @@ impl Dispatch for Sign {
         let object = helper::find_one_object(session, &attrs)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .prepare(KeyType::Rsa, &data, self.little_endian)?;
+        let data = self.format.prepare(KeyType::Rsa, &data)?;
         let mechanism = self.format.mechanism(KeyType::Rsa)?;
         let mut result = session.sign(&mechanism, object, &data)?;
         if self.little_endian {

sw/host/hsmtool/src/commands/rsa/verify.rs

@@ -25,7 +25,7 @@ pub struct Verify {
     label: Option<String>,
     #[arg(short, long, default_value = "sha256-hash", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data and result (for little-endian targets).
+    /// Reverse the result (for little-endian targets).
     #[arg(short = 'r', long)]
     little_endian: bool,
     /// The signature is at the given byte range of the input file.
@@ -51,9 +51,7 @@ impl Dispatch for Verify {
         let object = helper::find_one_object(session, &attrs)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .prepare(KeyType::Rsa, &data, self.little_endian)?;
+        let data = self.format.prepare(KeyType::Rsa, &data)?;
         let mechanism = self.format.mechanism(KeyType::Rsa)?;
         let mut signature = if let Some(filename) = &self.signature {
             std::fs::read(filename)?

sw/host/hsmtool/src/commands/spx/sign.rs

@@ -22,9 +22,6 @@ pub struct Sign {
     label: Option<String>,
     #[arg(short, long, default_value = "plain-text", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data (for little-endian targets).
-    #[arg(short = 'r', long)]
-    little_endian: bool,
     /// The SPHINCS+ signing domain.
     #[arg(short = 'd', long, default_value = "pure")]
     domain: SpxDomain,
@@ -45,9 +42,7 @@ impl Dispatch for Sign {
         let _token = hsm.token.as_deref().ok_or(HsmError::SessionRequired)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .spx_prepare(self.domain, &data, self.little_endian)?;
+        let data = self.format.spx_prepare(self.domain, &data)?;
         let result = spx.sign(self.label.as_deref(), self.id.as_deref(), &data)?;
         std::fs::write(&self.output, &result)?;
         Ok(Box::<BasicResult>::default())

sw/host/hsmtool/src/commands/spx/verify.rs

@@ -22,9 +22,6 @@ pub struct Verify {
     label: Option<String>,
     #[arg(short, long, default_value = "plain-text", help=SignData::HELP)]
     format: SignData,
-    /// Reverse the input data (for little-endian targets).
-    #[arg(short = 'r', long)]
-    little_endian: bool,
     /// The SPHINCS+ signing domain.
     #[arg(short = 'd', long, default_value = "pure")]
     domain: SpxDomain,
@@ -44,9 +41,7 @@ impl Dispatch for Verify {
         let _token = hsm.token.as_deref().ok_or(HsmError::SessionRequired)?;
 
         let data = std::fs::read(&self.input)?;
-        let data = self
-            .format
-            .spx_prepare(self.domain, &data, self.little_endian)?;
+        let data = self.format.spx_prepare(self.domain, &data)?;
         let signature = std::fs::read(&self.signature)?;
         let result = spx.verify(self.label.as_deref(), self.id.as_deref(), &data, &signature)?;
         Ok(Box::new(BasicResult {