diff --git a/crates/core/src/proxy.rs b/crates/core/src/proxy.rs
index 9cfabb9..8fe51ff 100644
--- a/crates/core/src/proxy.rs
+++ b/crates/core/src/proxy.rs
@@ -261,15 +261,7 @@ where
         }
 
         // Resolve via proxy pipeline (with metadata for after_dispatch)
-        let (action, metadata) = self
-            .resolve_request_with_metadata(
-                req.method.clone(),
-                req.path,
-                req.query,
-                req.headers,
-                req.source_ip,
-            )
-            .await;
+        let (action, metadata) = self.resolve_request_with_metadata(req).await;
 
         // Helper to extract response body size
         fn response_body_bytes(body: &ProxyResponseBody) -> Option<u64> {
@@ -361,9 +353,8 @@ where
         headers: &HeaderMap,
         source_ip: Option<IpAddr>,
     ) -> HandlerAction {
-        let (action, _metadata) = self
-            .resolve_request_with_metadata(method, path, query, headers, source_ip)
-            .await;
+        let req = RequestInfo::new(&method, path, query, headers, source_ip);
+        let (action, _metadata) = self.resolve_request_with_metadata(&req).await;
         action
     }
 
@@ -371,45 +362,43 @@ where
     /// [`RequestMetadata`] for post-dispatch callbacks (e.g. metering).
     pub(crate) async fn resolve_request_with_metadata(
         &self,
-        method: Method,
-        path: &str,
-        query: Option<&str>,
-        headers: &HeaderMap,
-        source_ip: Option<IpAddr>,
+        req: &RequestInfo<'_>,
     ) -> (HandlerAction, RequestMetadata) {
         let request_id = Uuid::new_v4().to_string();
 
         tracing::info!(
             request_id = %request_id,
-            method = %method,
-            path = %path,
-            query = ?query,
+            method = %req.method,
+            path = %req.path,
+            query = ?req.query,
             "incoming request"
         );
 
         // Determine host style
-        let host_style = determine_host_style(headers, self.virtual_host_domain.as_deref());
+        let host_style = determine_host_style(req.headers, self.virtual_host_domain.as_deref());
 
         // Parse the S3 operation
-        let operation = match request::parse_s3_request(&method, path, query, headers, host_style) {
-            Ok(op) => op,
-            Err(err) => return self.error_result(err, path, &request_id, source_ip),
-        };
+        let operation =
+            match request::parse_s3_request(req.method, req.path, req.query, req.headers, host_style) {
+                Ok(op) => op,
+                Err(err) => return self.error_result(err, req.path, &request_id, req.source_ip),
+            };
         tracing::debug!(operation = ?operation, "parsed S3 operation");
 
-        // Resolve identity
+        // Resolve identity — use the original client-facing path and query for
+        // signature verification when provided (e.g. path-mapping rewrites).
         let identity = match auth::resolve_identity(
-            &method,
-            path,
-            query.unwrap_or(""),
-            headers,
+            req.method,
+            req.signing_path.unwrap_or(req.path),
+            req.signing_query.or(req.query).unwrap_or(""),
+            req.headers,
             &self.credential_registry,
             self.credential_resolver.as_deref(),
         )
         .await
         {
             Ok(id) => id,
-            Err(err) => return self.error_result(err, path, &request_id, source_ip),
+            Err(err) => return self.error_result(err, req.path, &request_id, req.source_ip),
         };
         tracing::debug!(identity = ?identity, "resolved identity");
 
@@ -429,7 +418,7 @@ where
                     tracing::trace!("authorization passed");
                     Some(resolved)
                 }
-                Err(err) => return self.error_result(err, path, &request_id, source_ip),
+                Err(err) => return self.error_result(err, req.path, &request_id, req.source_ip),
             }
         } else {
             None
@@ -440,8 +429,8 @@ where
             identity: &identity,
             operation: &operation,
             bucket_config: resolved.as_ref().map(|r| Cow::Borrowed(&r.config)),
-            headers,
-            source_ip,
+            headers: req.headers,
+            source_ip: req.source_ip,
             request_id: &request_id,
             list_rewrite: resolved.as_ref().and_then(|r| r.list_rewrite.as_ref()),
             display_name: resolved.as_ref().and_then(|r| r.display_name.as_deref()),
@@ -454,7 +443,7 @@ where
             identity: Some(identity.clone()),
             operation: Some(operation.clone()),
             bucket: operation.bucket().map(str::to_string),
-            source_ip,
+            source_ip: req.source_ip,
         };
 
         match next.run(ctx).await {
@@ -483,7 +472,7 @@ where
                 }
                 (action, metadata)
             }
-            Err(err) => self.error_result(err, path, &request_id, source_ip),
+            Err(err) => self.error_result(err, req.path, &request_id, req.source_ip),
         }
     }
 
diff --git a/crates/core/src/route_handler.rs b/crates/core/src/route_handler.rs
index db6c91b..4a919b7 100644
--- a/crates/core/src/route_handler.rs
+++ b/crates/core/src/route_handler.rs
@@ -218,6 +218,18 @@ pub struct RequestInfo<'a> {
     /// Populated by the router when a route pattern matches. Empty when the
     /// request is constructed via [`RequestInfo::new`].
     pub params: Params,
+    /// The original path as seen by the client, used for SigV4 signature
+    /// verification when the proxy rewrites paths before dispatch.
+    ///
+    /// When `None`, `path` is used for both operation parsing and signature
+    /// verification.
+    pub signing_path: Option<&'a str>,
+    /// The original query string as seen by the client, used for SigV4
+    /// signature verification when the proxy rewrites query parameters.
+    ///
+    /// When `None`, `query` is used for both operation parsing and signature
+    /// verification.
+    pub signing_query: Option<&'a str>,
 }
 
 impl<'a> RequestInfo<'a> {
@@ -236,8 +248,29 @@ impl<'a> RequestInfo<'a> {
             headers,
             source_ip,
             params: Params::default(),
+            signing_path: None,
+            signing_query: None,
         }
     }
+
+    /// Set the original client-facing path for SigV4 signature verification.
+    ///
+    /// Use this when the proxy rewrites paths (e.g. path-mapping) so that
+    /// signature verification uses the path the client actually signed.
+    pub fn with_signing_path(mut self, signing_path: &'a str) -> Self {
+        self.signing_path = Some(signing_path);
+        self
+    }
+
+    /// Set the original client-facing query string for SigV4 signature verification.
+    ///
+    /// Use this when the proxy rewrites query parameters (e.g. path-mapping
+    /// strips prefix segments from the `prefix` parameter) so that signature
+    /// verification uses the query string the client actually signed.
+    pub fn with_signing_query(mut self, signing_query: Option<&'a str>) -> Self {
+        self.signing_query = signing_query;
+        self
+    }
 }
 
 /// A pluggable handler that can intercept requests before proxy dispatch.
diff --git a/crates/core/src/router.rs b/crates/core/src/router.rs
index ef98187..b6bcc44 100644
--- a/crates/core/src/router.rs
+++ b/crates/core/src/router.rs
@@ -66,6 +66,8 @@ impl Router {
             query: req.query,
             headers: req.headers,
             source_ip: req.source_ip,
+            signing_path: req.signing_path,
+            signing_query: req.signing_query,
         };
         matched
             .value
diff --git a/crates/path-mapping/src/lib.rs b/crates/path-mapping/src/lib.rs
index a60e3f7..6df3dec 100644
--- a/crates/path-mapping/src/lib.rs
+++ b/crates/path-mapping/src/lib.rs
@@ -39,20 +39,22 @@
 //! assert_eq!(mapped.display_bucket, "acme");
 //!
 //! // Full request rewrite (path + query)
-//! let (path, query) = mapping.rewrite_request(
+//! let result = mapping.rewrite_request(
 //!     "/acme/data/report.csv",
 //!     None,
 //! );
-//! assert_eq!(path, "/acme:data/report.csv");
-//! assert_eq!(query, None);
+//! assert_eq!(result.path, "/acme:data/report.csv");
+//! assert_eq!(result.query, None);
+//! assert_eq!(result.signing_path, "/acme/data/report.csv");
 //!
 //! // Prefix-based list rewrite
-//! let (path, query) = mapping.rewrite_request(
+//! let result = mapping.rewrite_request(
 //!     "/acme",
 //!     Some("list-type=2&prefix=data/subdir/"),
 //! );
-//! assert_eq!(path, "/acme:data");
-//! assert_eq!(query, Some("list-type=2&prefix=subdir/".to_string()));
+//! assert_eq!(result.path, "/acme:data");
+//! assert_eq!(result.query, Some("list-type=2&prefix=subdir/".to_string()));
+//! assert_eq!(result.signing_query, Some("list-type=2&prefix=data/subdir/".to_string()));
 //! ```
 
 use multistore::api::list_rewrite::ListRewrite;
@@ -74,6 +76,22 @@ pub struct PathMapping {
     pub display_bucket_segments: usize,
 }
 
+/// Result of rewriting a request path and query string.
+///
+/// Contains both the rewritten values (for S3 operation parsing) and the
+/// original values (for SigV4 signature verification).
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RewriteResult {
+    /// Rewritten path for S3 operation parsing.
+    pub path: String,
+    /// Rewritten query for operation parsing.
+    pub query: Option<String>,
+    /// Original client path for SigV4 verification.
+    pub signing_path: String,
+    /// Original client query for SigV4 verification.
+    pub signing_query: Option<String>,
+}
+
 /// Result of mapping a request path.
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct MappedPath {
@@ -208,14 +226,22 @@ impl PathMapping {
     ///
     /// 3. **Pass-through**: all other paths are returned unchanged. Route handlers
     ///    or the gateway itself will handle them.
-    pub fn rewrite_request(&self, path: &str, query: Option<&str>) -> (String, Option<String>) {
+    pub fn rewrite_request(&self, path: &str, query: Option<&str>) -> RewriteResult {
+        let signing_path = path.to_string();
+        let signing_query = query.map(|q| q.to_string());
+
         // Case 1: enough path segments to map directly
         if let Some(mapped) = self.parse(path) {
             let rewritten_path = match mapped.key {
                 Some(ref key) => format!("/{}/{}", mapped.bucket, key),
                 None => format!("/{}", mapped.bucket),
             };
-            return (rewritten_path, query.map(|q| q.to_string()));
+            return RewriteResult {
+                path: rewritten_path,
+                query: query.map(|q| q.to_string()),
+                signing_path,
+                signing_query,
+            };
         }
 
         // Case 2: single-segment path with a list-type query and non-empty prefix
@@ -225,14 +251,26 @@ impl PathMapping {
             if is_list_request(query_str) {
                 if let Some(prefix) = extract_query_param(query_str, "prefix") {
                     if !prefix.is_empty() {
-                        return self.rewrite_prefix_to_bucket(trimmed, &prefix, query_str);
+                        let (rewritten_path, rewritten_query) =
+                            self.rewrite_prefix_to_bucket(trimmed, &prefix, query_str);
+                        return RewriteResult {
+                            path: rewritten_path,
+                            query: rewritten_query,
+                            signing_path,
+                            signing_query,
+                        };
                     }
                 }
             }
         }
 
         // Case 3: pass through unchanged
-        (path.to_string(), query.map(|q| q.to_string()))
+        RewriteResult {
+            path: path.to_string(),
+            query: query.map(|q| q.to_string()),
+            signing_path,
+            signing_query,
+        }
     }
 
     /// Fold the first prefix component into the bucket name.
diff --git a/crates/path-mapping/tests/mapping_tests.rs b/crates/path-mapping/tests/mapping_tests.rs
index 0cedbf0..68b4c46 100644
--- a/crates/path-mapping/tests/mapping_tests.rs
+++ b/crates/path-mapping/tests/mapping_tests.rs
@@ -115,104 +115,113 @@ fn trailing_slash_on_bucket_segments() {
 #[test]
 fn rewrite_multi_segment_path() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account/product/file.parquet", None),
-        ("/account--product/file.parquet".to_string(), None)
-    );
+    let result = mapping.rewrite_request("/account/product/file.parquet", None);
+    assert_eq!(result.path, "/account--product/file.parquet");
+    assert_eq!(result.query, None);
+    assert_eq!(result.signing_path, "/account/product/file.parquet");
+    assert_eq!(result.signing_query, None);
 }
 
 #[test]
 fn rewrite_multi_segment_nested_key() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account/product/dir/sub/file.parquet", None),
-        ("/account--product/dir/sub/file.parquet".to_string(), None)
-    );
+    let result = mapping.rewrite_request("/account/product/dir/sub/file.parquet", None);
+    assert_eq!(result.path, "/account--product/dir/sub/file.parquet");
+    assert_eq!(result.query, None);
+    assert_eq!(result.signing_path, "/account/product/dir/sub/file.parquet");
+    assert_eq!(result.signing_query, None);
 }
 
 #[test]
 fn rewrite_bucket_only_no_key() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account/product", Some("list-type=2")),
-        (
-            "/account--product".to_string(),
-            Some("list-type=2".to_string())
-        )
-    );
+    let result = mapping.rewrite_request("/account/product", Some("list-type=2"));
+    assert_eq!(result.path, "/account--product");
+    assert_eq!(result.query, Some("list-type=2".to_string()));
+    assert_eq!(result.signing_path, "/account/product");
+    assert_eq!(result.signing_query, Some("list-type=2".to_string()));
 }
 
 #[test]
 fn rewrite_prefix_routed_list() {
     let mapping = default_mapping();
+    let result = mapping.rewrite_request("/account", Some("list-type=2&prefix=product/"));
+    assert_eq!(result.path, "/account--product");
+    assert_eq!(result.query, Some("list-type=2&prefix=".to_string()));
+    assert_eq!(result.signing_path, "/account");
     assert_eq!(
-        mapping.rewrite_request("/account", Some("list-type=2&prefix=product/")),
-        (
-            "/account--product".to_string(),
-            Some("list-type=2&prefix=".to_string())
-        )
+        result.signing_query,
+        Some("list-type=2&prefix=product/".to_string())
     );
 }
 
 #[test]
 fn rewrite_prefix_routed_list_with_subdir() {
     let mapping = default_mapping();
+    let result = mapping.rewrite_request("/account", Some("list-type=2&prefix=product/subdir/"));
+    assert_eq!(result.path, "/account--product");
+    assert_eq!(result.query, Some("list-type=2&prefix=subdir/".to_string()));
+    assert_eq!(result.signing_path, "/account");
     assert_eq!(
-        mapping.rewrite_request("/account", Some("list-type=2&prefix=product/subdir/")),
-        (
-            "/account--product".to_string(),
-            Some("list-type=2&prefix=subdir/".to_string())
-        )
+        result.signing_query,
+        Some("list-type=2&prefix=product/subdir/".to_string())
     );
 }
 
 #[test]
 fn rewrite_url_encoded_prefix() {
     let mapping = default_mapping();
+    let result =
+        mapping.rewrite_request("/account", Some("list-type=2&prefix=my%20product/subdir/"));
+    assert_eq!(result.path, "/account--my product");
+    assert_eq!(result.query, Some("list-type=2&prefix=subdir/".to_string()));
+    assert_eq!(result.signing_path, "/account");
     assert_eq!(
-        mapping.rewrite_request("/account", Some("list-type=2&prefix=my%20product/subdir/")),
-        (
-            "/account--my product".to_string(),
-            Some("list-type=2&prefix=subdir/".to_string())
-        )
+        result.signing_query,
+        Some("list-type=2&prefix=my%20product/subdir/".to_string())
     );
 }
 
 #[test]
 fn rewrite_single_segment_no_list_passes_through() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account", None),
-        ("/account".to_string(), None)
-    );
+    let result = mapping.rewrite_request("/account", None);
+    assert_eq!(result.path, "/account");
+    assert_eq!(result.query, None);
+    assert_eq!(result.signing_path, "/account");
+    assert_eq!(result.signing_query, None);
 }
 
 #[test]
 fn rewrite_single_segment_list_no_prefix_passes_through() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account", Some("list-type=2")),
-        ("/account".to_string(), Some("list-type=2".to_string()))
-    );
+    let result = mapping.rewrite_request("/account", Some("list-type=2"));
+    assert_eq!(result.path, "/account");
+    assert_eq!(result.query, Some("list-type=2".to_string()));
+    assert_eq!(result.signing_path, "/account");
+    assert_eq!(result.signing_query, Some("list-type=2".to_string()));
 }
 
 #[test]
 fn rewrite_root_passes_through() {
     let mapping = default_mapping();
-    assert_eq!(mapping.rewrite_request("/", None), ("/".to_string(), None));
+    let result = mapping.rewrite_request("/", None);
+    assert_eq!(result.path, "/");
+    assert_eq!(result.query, None);
 }
 
 #[test]
 fn rewrite_empty_passes_through() {
     let mapping = default_mapping();
-    assert_eq!(mapping.rewrite_request("", None), ("".to_string(), None));
+    let result = mapping.rewrite_request("", None);
+    assert_eq!(result.path, "");
+    assert_eq!(result.query, None);
 }
 
 #[test]
 fn rewrite_trailing_slash_passes_through() {
     let mapping = default_mapping();
-    assert_eq!(
-        mapping.rewrite_request("/account/", Some("list-type=2")),
-        ("/account/".to_string(), Some("list-type=2".to_string()))
-    );
+    let result = mapping.rewrite_request("/account/", Some("list-type=2"));
+    assert_eq!(result.path, "/account/");
+    assert_eq!(result.query, Some("list-type=2".to_string()));
 }