diff --git a/internal/sigv4auth/auth.go b/internal/sigv4auth/auth.go
new file mode 100644
index 0000000..e57a16d
--- /dev/null
+++ b/internal/sigv4auth/auth.go
@@ -0,0 +1,247 @@
+// Copyright 2026 Versity Software
+// This file is licensed under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sigv4auth
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"strings"
+	"time"
+	"unicode"
+)
+
+const (
+	AlgorithmHMACSHA256 = "AWS4-HMAC-SHA256"
+	Terminal            = "aws4_request"
+	ServiceS3           = "s3"
+	ServiceIAM          = "iam"
+	ServiceSTS          = "sts"
+
+	ISO8601Format = "20060102T150405Z"
+	YYYYMMDD      = "20060102"
+
+	// HeaderSecurityToken is the header a temporary credential's
+	// SessionToken is presented in, matching AWS's X-Amz-Security-Token.
+	HeaderSecurityToken = "X-Amz-Security-Token"
+
+	// TempAccessKeyIDPrefix marks temporary credentials minted by
+	// AssumeRoleWithWebIdentity, matching AWS's ASIA… convention that
+	// distinguishes them from long-term AKIA… access keys.
+	TempAccessKeyIDPrefix = "ASIA"
+)
+
+// IsTempAccessKeyID reports whether accessKeyID is a temporary (session)
+// credential rather than a long-term AKIA… access key.
+func IsTempAccessKeyID(accessKeyID string) bool {
+	return strings.HasPrefix(accessKeyID, TempAccessKeyIDPrefix)
+}
+
+type ParseErrorKind string
+
+const (
+	ErrInvalidAuthorizationHeader      ParseErrorKind = "invalid_authorization_header"
+	ErrUnsupportedAuthorizationVersion ParseErrorKind = "unsupported_authorization_version"
+	ErrInvalidAuthorizationType        ParseErrorKind = "invalid_authorization_type"
+	ErrMissingComponents               ParseErrorKind = "missing_components"
+	ErrMissingCredential               ParseErrorKind = "missing_credential"
+	ErrMissingSignedHeaders            ParseErrorKind = "missing_signed_headers"
+	ErrMissingSignature                ParseErrorKind = "missing_signature"
+	ErrMalformedComponent              ParseErrorKind = "malformed_component"
+	ErrMalformedCredential             ParseErrorKind = "malformed_credential"
+	ErrIncorrectService                ParseErrorKind = "incorrect_service"
+	ErrIncorrectTerminal               ParseErrorKind = "incorrect_terminal"
+	ErrInvalidDateFormat               ParseErrorKind = "invalid_date_format"
+)
+
+type ParseError struct {
+	Kind     ParseErrorKind
+	Input    string
+	Value    string
+	Expected string
+	Actual   string
+}
+
+func (e *ParseError) Error() string {
+	if e == nil {
+		return ""
+	}
+	switch e.Kind {
+	case ErrIncorrectService, ErrIncorrectTerminal:
+		return fmt.Sprintf("sigv4 %s: expected %q, got %q", e.Kind, e.Expected, e.Actual)
+	case ErrInvalidAuthorizationType, ErrMalformedComponent, ErrInvalidDateFormat:
+		return fmt.Sprintf("sigv4 %s: %q", e.Kind, e.Value)
+	default:
+		return string(e.Kind)
+	}
+}
+
+// AuthData is the parsed authorization data from an AWS SigV4 Authorization header.
+type AuthData struct {
+	Algorithm     string
+	Access        string
+	Region        string
+	Service       string
+	SignedHeaders string
+	Signature     string
+	Date          string
+}
+
+type CredentialsScope struct {
+	Access  string
+	Date    string
+	Region  string
+	Service string
+}
+
+// HexBytes returns the hex byte representation used by AWS-style diagnostic
+// signature mismatch errors.
+func HexBytes(s string) string {
+	b := []byte(s)
+
+	parts := make([]string, len(b))
+	for i, v := range b {
+		parts[i] = fmt.Sprintf("%02x", v)
+	}
+
+	return strings.Join(parts, " ")
+}
+
+func PayloadSHA256Hex(payload []byte) string {
+	hashedPayload := sha256.Sum256(payload)
+	return hex.EncodeToString(hashedPayload[:])
+}
+
+// ParseAuthorization parses and validates an AWS SigV4 Authorization header.
+// The credential scope service must match expectedService.
+func ParseAuthorization(authorization, expectedService string) (AuthData, error) {
+	a := AuthData{}
+
+	authParts := strings.SplitN(authorization, " ", 2)
+	for i, el := range authParts {
+		if strings.Contains(el, " ") {
+			authParts[i] = removeSpace(el)
+		}
+	}
+
+	if len(authParts) < 2 {
+		return a, &ParseError{Kind: ErrInvalidAuthorizationHeader, Input: authorization}
+	}
+
+	algo := authParts[0]
+	if algo == "AWS" {
+		return a, &ParseError{Kind: ErrUnsupportedAuthorizationVersion, Value: algo}
+	}
+	if algo != AlgorithmHMACSHA256 {
+		return a, &ParseError{Kind: ErrInvalidAuthorizationType, Value: algo}
+	}
+
+	kvPairs := strings.Split(authParts[1], ",")
+	if len(kvPairs) != 3 {
+		return a, &ParseError{Kind: ErrMissingComponents, Input: authorization}
+	}
+
+	var access, region, service, signedHeaders, signature, date string
+	for i, kv := range kvPairs {
+		keyValue := strings.Split(kv, "=")
+		if len(keyValue) != 2 {
+			return a, &ParseError{Kind: ErrMalformedComponent, Value: kv}
+		}
+		key, value := keyValue[0], keyValue[1]
+		switch i {
+		case 0:
+			if key != "Credential" {
+				return a, &ParseError{Kind: ErrMissingCredential}
+			}
+		case 1:
+			if key != "SignedHeaders" {
+				return a, &ParseError{Kind: ErrMissingSignedHeaders}
+			}
+		case 2:
+			if key != "Signature" {
+				return a, &ParseError{Kind: ErrMissingSignature}
+			}
+		}
+
+		switch key {
+		case "Credential":
+			creds, err := ParseCredentials(value, expectedService)
+			if err != nil {
+				return a, err
+			}
+			access = creds.Access
+			date = creds.Date
+			region = creds.Region
+			service = creds.Service
+		case "SignedHeaders":
+			signedHeaders = value
+		case "Signature":
+			signature = value
+		}
+	}
+
+	return AuthData{
+		Algorithm:     algo,
+		Access:        access,
+		Region:        region,
+		Service:       service,
+		SignedHeaders: signedHeaders,
+		Signature:     signature,
+		Date:          date,
+	}, nil
+}
+
+func ParseCredentials(input, expectedService string) (*CredentialsScope, error) {
+	creds := strings.Split(input, "/")
+	if len(creds) != 5 {
+		return nil, &ParseError{Kind: ErrMalformedCredential, Input: input}
+	}
+	if creds[3] != expectedService {
+		return nil, &ParseError{
+			Kind:     ErrIncorrectService,
+			Input:    input,
+			Expected: expectedService,
+			Actual:   creds[3],
+		}
+	}
+	if creds[4] != Terminal {
+		return nil, &ParseError{
+			Kind:     ErrIncorrectTerminal,
+			Input:    input,
+			Expected: Terminal,
+			Actual:   creds[4],
+		}
+	}
+	if _, err := time.Parse(YYYYMMDD, creds[1]); err != nil {
+		return nil, &ParseError{Kind: ErrInvalidDateFormat, Input: input, Value: creds[1]}
+	}
+
+	return &CredentialsScope{
+		Access:  creds[0],
+		Date:    creds[1],
+		Region:  creds[2],
+		Service: creds[3],
+	}, nil
+}
+
+func removeSpace(str string) string {
+	var b strings.Builder
+	b.Grow(len(str))
+	for _, ch := range str {
+		if !unicode.IsSpace(ch) {
+			b.WriteRune(ch)
+		}
+	}
+	return b.String()
+}
diff --git a/s3api/utils/auth-reader.go b/s3api/utils/auth-reader.go
new file mode 100644
index 0000000..8161b5e
--- /dev/null
+++ b/s3api/utils/auth-reader.go
@@ -0,0 +1,171 @@
+// Copyright 2023 Versity Software
+// This file is licensed under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package utils
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"time"
+
+	"github.com/gofiber/fiber/v3"
+	"github.com/versity/versitygw/internal/sigv4auth"
+	"github.com/versity/versitygw/s3err"
+)
+
+const (
+	iso8601Format = sigv4auth.ISO8601Format
+	yyyymmdd      = sigv4auth.YYYYMMDD
+)
+
+func HexBytes(s string) string {
+	return sigv4auth.HexBytes(s)
+}
+
+const (
+	service = sigv4auth.ServiceS3
+)
+
+// CheckValidSignature validates the ctx v4 auth signature against
+// derivedKey — the request's kSigning value, either derived locally from a
+// known secret or obtained from a standalone IAM service that never reveals
+// the secret itself.
+func CheckValidSignature(ctx fiber.Ctx, auth AuthData, derivedKey []byte, checksum string, tdate time.Time, contentLen int64) (string, error) {
+	result, err := sigv4auth.CheckSignature(ctx, auth, derivedKey, checksum, tdate, contentLen, sigv4auth.CheckOptions{
+		Service: service,
+	})
+	if err != nil {
+		return "", mapSigV4Error(err)
+	}
+
+	return result.CanonicalString, nil
+}
+
+// AuthData is the parsed authorization data from the header.
+type AuthData = sigv4auth.AuthData
+
+// ParseAuthorization returns the parsed fields for the aws v4 auth header
+// example authorization string from aws docs:
+// Authorization: AWS4-HMAC-SHA256
+// Credential=AKIAIOSFODNN7EXAMPLE/20130524/us-east-1/s3/aws4_request,
+// SignedHeaders=host;range;x-amz-date,
+// Signature=fe5f80f77d5fa3beca038a248ff027d0445342fe2855ddc963176630326f1024
+func ParseAuthorization(authorization string) (AuthData, error) {
+	authData, err := sigv4auth.ParseAuthorization(authorization, service)
+	if err != nil {
+		return AuthData{}, mapSigV4Error(err)
+	}
+	return authData, nil
+}
+
+type CredentialsScope = sigv4auth.CredentialsScope
+
+type CredsError interface {
+	MalformedCredential(string) s3err.S3Error
+	IncorrectService(string, string) s3err.S3Error
+	IncorrectTerminal(string, string) s3err.S3Error
+	InvalidDateFormat(string, string) s3err.S3Error
+}
+
+func ParseCredentials(input string, errHandler CredsError) (*CredentialsScope, error) {
+	creds, err := sigv4auth.ParseCredentials(input, service)
+	if err != nil {
+		return nil, mapCredentialsError(input, err, errHandler)
+	}
+	return creds, nil
+}
+
+// SignPostPolicy signs a POST-policy document with derivedKey
+func SignPostPolicy(base64Policy string, derivedKey []byte) (string, error) {
+	h := hmac.New(sha256.New, derivedKey)
+	h.Write([]byte(base64Policy))
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+func mapSigV4Error(err error) error {
+	var parseErr *sigv4auth.ParseError
+	if errors.As(err, &parseErr) {
+		return mapAuthParseError(parseErr)
+	}
+
+	var headersErr *sigv4auth.HeadersNotSignedError
+	if errors.As(err, &headersErr) {
+		return s3err.GetHeadersNotSignedErr(headersErr.Headers)
+	}
+
+	var sigErr *sigv4auth.SignatureMismatchError
+	if errors.As(err, &sigErr) {
+		return s3err.GetSignatureDoesNotMatchErr(
+			sigErr.AccessKeyID,
+			sigErr.StringToSign,
+			sigErr.SignatureProvided,
+			sigErr.StringToSignBytes,
+			sigErr.CanonicalRequest,
+			sigErr.CanonicalRequestBytes,
+		)
+	}
+
+	return err
+}
+
+func mapAuthParseError(err *sigv4auth.ParseError) error {
+	switch err.Kind {
+	case sigv4auth.ErrInvalidAuthorizationHeader:
+		return s3err.GetInvalidArgumentErr(s3err.InvalidArgAuthHeader, err.Input)
+	case sigv4auth.ErrUnsupportedAuthorizationVersion:
+		return s3err.GetAPIError(s3err.ErrUnsupportedAuthorizationMechanism)
+	case sigv4auth.ErrInvalidAuthorizationType:
+		return s3err.GetInvalidArgumentErr(s3err.InvalidArgAuthorizationType, err.Value)
+	case sigv4auth.ErrMissingComponents:
+		return s3err.MalformedAuth.MissingComponents()
+	case sigv4auth.ErrMissingCredential:
+		return s3err.MalformedAuth.MissingCredential()
+	case sigv4auth.ErrMissingSignedHeaders:
+		return s3err.MalformedAuth.MissingSignedHeaders()
+	case sigv4auth.ErrMissingSignature:
+		return s3err.MalformedAuth.MissingSignature()
+	case sigv4auth.ErrMalformedComponent:
+		return s3err.MalformedAuth.MalformedComponent(err.Value)
+	default:
+		return mapCredentialsParseError(err, s3err.MalformedAuth)
+	}
+}
+
+func mapCredentialsError(input string, err error, errHandler CredsError) error {
+	var parseErr *sigv4auth.ParseError
+	if !errors.As(err, &parseErr) {
+		return err
+	}
+	if parseErr.Input == "" {
+		parseErr.Input = input
+	}
+	return mapCredentialsParseError(parseErr, errHandler)
+}
+
+func mapCredentialsParseError(err *sigv4auth.ParseError, errHandler CredsError) error {
+	switch err.Kind {
+	case sigv4auth.ErrMalformedCredential:
+		return errHandler.MalformedCredential(err.Input)
+	case sigv4auth.ErrIncorrectService:
+		return errHandler.IncorrectService(err.Input, err.Actual)
+	case sigv4auth.ErrIncorrectTerminal:
+		return errHandler.IncorrectTerminal(err.Input, err.Actual)
+	case sigv4auth.ErrInvalidDateFormat:
+		return errHandler.InvalidDateFormat(err.Input, err.Value)
+	default:
+		return err
+	}
+}
diff --git a/s3api/utils/auth_test.go b/s3api/utils/auth_test.go
new file mode 100644
index 0000000..af1f97a
--- /dev/null
+++ b/s3api/utils/auth_test.go
@@ -0,0 +1,146 @@
+// Copyright 2023 Versity Software
+// This file is licensed under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package utils
+
+import (
+	"net"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/gofiber/fiber/v3"
+	"github.com/valyala/fasthttp"
+	"github.com/valyala/fasthttp/fasthttputil"
+	"github.com/versity/versitygw/internal/sigv4auth"
+)
+
+func TestAuthParse(t *testing.T) {
+	vectors := []struct {
+		name    string // name of test string
+		authstr string // Authorization string
+		algo    string
+		sig     string
+	}{
+		{
+			name:    "restic",
+			authstr: "AWS4-HMAC-SHA256 Credential=user/20240116/us-east-1/s3/aws4_request,SignedHeaders=content-md5;host;x-amz-content-sha256;x-amz-date;x-amz-decoded-content-length,Signature=d5199fc7f3aa35dd3d400427be2ae4c98bfad390785280cbb9eea015b51e12ac",
+			algo:    "AWS4-HMAC-SHA256",
+			sig:     "d5199fc7f3aa35dd3d400427be2ae4c98bfad390785280cbb9eea015b51e12ac",
+		},
+		{
+			name:    "aws eaxample",
+			authstr: "AWS4-HMAC-SHA256 Credential=AKIAIOSFODNN7EXAMPLE/20130524/us-east-1/s3/aws4_request, SignedHeaders=host;range;x-amz-date, Signature=fe5f80f77d5fa3beca038a248ff027d0445342fe2855ddc963176630326f1024",
+			algo:    "AWS4-HMAC-SHA256",
+			sig:     "fe5f80f77d5fa3beca038a248ff027d0445342fe2855ddc963176630326f1024",
+		},
+		{
+			name:    "s3browser",
+			authstr: "AWS4-HMAC-SHA256 Credential=access_key/20240206/us-east-1/s3/aws4_request,SignedHeaders=host;user-agent;x-amz-content-sha256;x-amz-date, Signature=37a35d96998d786113ad420c57c22c5433f6aca74f88f26566caa047fc3601c6",
+			algo:    "AWS4-HMAC-SHA256",
+			sig:     "37a35d96998d786113ad420c57c22c5433f6aca74f88f26566caa047fc3601c6",
+		},
+	}
+
+	for _, v := range vectors {
+		t.Run(v.name, func(t *testing.T) {
+			data, err := ParseAuthorization(v.authstr)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if data.Algorithm != v.algo {
+				t.Errorf("algo got %v, expected %v", data.Algorithm, v.algo)
+			}
+			if data.Signature != v.sig {
+				t.Errorf("signature got %v, expected %v", data.Signature, v.sig)
+			}
+		})
+	}
+}
+
+// 2024/02/06 21:03:28 Request headers:
+// 2024/02/06 21:03:28 Host: 172.21.0.160:11000
+// 2024/02/06 21:03:28 User-Agent: S3 Browser/11.5.7 (https://s3browser.com)
+// 2024/02/06 21:03:28 Authorization: AWS4-HMAC-SHA256 Credential=access_key/20240206/us-east-1/s3/aws4_request,SignedHeaders=host;user-agent;x-amz-content-sha256;x-amz-date, Signature=37a35d96998d786113ad420c57c22c5433f6aca74f88f26566caa047fc3601c6
+// 2024/02/06 21:03:28 X-Amz-Content-Sha256: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
+// 2024/02/06 21:03:28 X-Amz-Date: 20240206T210328Z
+func Test_Client_UserAgent(t *testing.T) {
+	signedHdrs := []string{"host", "user-agent", "x-amz-content-sha256", "x-amz-date"}
+	access := "access_key"
+	secret := "secret_key"
+	region := "us-east-1"
+	host := "172.21.0.160:11000"
+	agent := "S3 Browser/11.5.7 (https://s3browser.com)"
+	expectedSig := "37a35d96998d786113ad420c57c22c5433f6aca74f88f26566caa047fc3601c6"
+	dateStr := "20240206T210328Z"
+
+	app := fiber.New(fiber.Config{})
+
+	tdate, err := time.Parse(iso8601Format, dateStr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	app.Get("/", func(c fiber.Ctx) error {
+		auth := sigv4auth.AuthData{
+			Access:        access,
+			Region:        region,
+			Service:       service,
+			SignedHeaders: strings.Join(signedHdrs, ";"),
+			Signature:     expectedSig,
+		}
+		derivedKey := sigv4auth.DeriveKey(secret, dateStr[:8], region, service)
+		opts := sigv4auth.CheckOptions{DisableURIPathEscaping: true}
+		contentLen := int64(c.Request().Header.ContentLength())
+
+		if _, err := sigv4auth.CheckSignature(c, auth, derivedKey, zeroLenSig, tdate, contentLen, opts); err != nil {
+			t.Errorf("CheckSignature: %v", err)
+		}
+
+		return c.Send(c.Request().Header.UserAgent())
+	})
+
+	ln := fasthttputil.NewInmemoryListener()
+	go func() {
+		err := app.Listener(ln)
+		if err != nil {
+			panic(err)
+		}
+	}()
+
+	client := fasthttp.Client{
+		Dial: func(_ string) (net.Conn, error) { return ln.Dial() },
+	}
+
+	req := fasthttp.AcquireRequest()
+	resp := fasthttp.AcquireResponse()
+	defer fasthttp.ReleaseRequest(req)
+	defer fasthttp.ReleaseResponse(resp)
+
+	// Host/User-Agent/X-Amz-Content-Sha256/X-Amz-Date are sent as real
+	// headers, reproducing the captured request verbatim, so CheckSignature
+	// extracts them straight off the live fiber.Ctx like it does for any
+	// real request.
+	req.SetRequestURI("http://" + host + "/")
+	req.Header.SetUserAgent(agent)
+	req.Header.Set("X-Amz-Content-Sha256", zeroLenSig)
+	req.Header.Set("X-Amz-Date", dateStr)
+	if err := client.Do(req, resp); err != nil {
+		t.Fatal(err)
+	}
+
+	if got := string(resp.Body()); got != agent {
+		t.Errorf("user-agent got %q, expected %q", got, agent)
+	}
+}
diff --git a/tests/integration/sigv4_auth.go b/tests/integration/sigv4_auth.go
new file mode 100644
index 0000000..551b43f
--- /dev/null
+++ b/tests/integration/sigv4_auth.go
@@ -0,0 +1,666 @@
+// Copyright 2023 Versity Software
+// This file is licensed under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package integration
+
+import (
+	"encoding/xml"
+	"fmt"
+	"io"
+	"net/http"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/aws/aws-sdk-go-v2/service/s3"
+	"github.com/versity/versitygw/s3err"
+)
+
+func Authentication_invalid_auth_header(s *S3Conf) error {
+	testName := "Authentication_invalid_auth_header"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		req.Header.Set("Authorization", "invalid_header")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetInvalidArgumentErr(s3err.InvalidArgAuthHeader, "invalid_header"))
+	})
+}
+
+func Authentication_unsupported_signature_version(s *S3Conf) error {
+	testName := "Authentication_unsupported_signature_version"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		authHdr := req.Header.Get("Authorization")
+		authHdr = strings.Replace(authHdr, "AWS4-HMAC-SHA256", "AWS2-HMAC-SHA1", 1)
+		req.Header.Set("Authorization", authHdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetInvalidArgumentErr(s3err.InvalidArgAuthorizationType, "AWS2-HMAC-SHA1"))
+	})
+}
+
+func Authentication_missing_components(s *S3Conf) error {
+	testName := "Authentication_missing_components"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		// missing SignedHeaders component
+		req.Header.Set("Authorization", "AWS4-HMAC-SHA256 Credential=access/20250912/us-east-1/s3/aws4_request,Signature=5fb279ae552098ea7c5c807df54cdb159e74939e19449b29831552639ec34b29")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MissingComponents())
+	})
+}
+
+func Authentication_malformed_component(s *S3Conf) error {
+	testName := "Authentication_malformed_component"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		// malformed SignedHeaders
+		req.Header.Set("Authorization", "AWS4-HMAC-SHA256 Credential=access/20250912/us-east-1/s3/aws4_request,SignedHeaders-Content-Length,Signature=signature")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MalformedComponent("SignedHeaders-Content-Length"))
+	})
+}
+
+func Authentication_missing_credentials(s *S3Conf) error {
+	testName := "Authentication_missing_credentials"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		// missing Credentials
+		req.Header.Set("Authorization", "AWS4-HMAC-SHA256 missing_creds=access/20250912/us-east-1/s3/aws4_request,SignedHeaders=content-length;x-amz-date,Signature=5fb279ae552098ea7c5c807df54cdb159e74939e19449b29831552639ec34b29")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MissingCredential())
+	})
+}
+
+func Authentication_missing_signedheaders(s *S3Conf) error {
+	testName := "Authentication_missing_signedheaders"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		// missing SignedHeaders
+		req.Header.Set("Authorization", "AWS4-HMAC-SHA256 Credential=access/20250912/us-east-1/s3/aws4_request,missing=content-length;x-amz-date,Signature=5fb279ae552098ea7c5c807df54cdb159e74939e19449b29831552639ec34b29")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MissingSignedHeaders())
+	})
+}
+
+func Authentication_missing_signature(s *S3Conf) error {
+	testName := "Authentication_missing_signature"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		// missing Signature
+		req.Header.Set("Authorization", "AWS4-HMAC-SHA256 Credential=access/20250912/us-east-1/s3/aws4_request,SignedHeaders=content-length;x-amz-date,missing=5fb279ae552098ea7c5c807df54cdb159e74939e19449b29831552639ec34b29")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MissingSignature())
+	})
+}
+
+func Authentication_malformed_credential(s *S3Conf) error {
+	testName := "Authentication_malformed_credential"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=[^,]+,")
+		hdr := regExp.ReplaceAllString(authHdr, "Credential=access/32234/us-east-1/s3/extra/things,")
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.MalformedCredential(""))
+	})
+}
+
+func Authentication_credentials_invalid_terminal(s *S3Conf) error {
+	testName := "Authentication_credentials_invalid_terminal"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=[^,]+,")
+		hdr := regExp.ReplaceAllString(authHdr, "Credential=access/32234/us-east-1/s3/aws_request,")
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.IncorrectTerminal("", "aws_request"))
+	})
+}
+
+func Authentication_credentials_incorrect_service(s *S3Conf) error {
+	testName := "Authentication_credentials_incorrect_service"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=[^,]+,")
+		hdr := regExp.ReplaceAllString(authHdr, "Credential=access/32234/us-east-1/ec2/aws4_request,")
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.IncorrectService("", "ec2"))
+	})
+}
+
+func Authentication_credentials_incorrect_region(s *S3Conf) error {
+	testName := "Authentication_credentials_incorrect_region"
+	cfg := *s
+	if cfg.awsRegion == "us-east-1" {
+		cfg.awsRegion = "us-west-1"
+	} else {
+		cfg.awsRegion = "us-east-1"
+	}
+	return authHandler(&cfg, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.IncorrectRegion(s.awsRegion, cfg.awsRegion))
+	})
+}
+
+// Authentication_credentials_incorrect_region_head verifies that a HEAD request
+// signed for the wrong region reports the gateway region in the
+// x-amz-bucket-region response header. HEAD responses carry no body, so the
+// header is the only channel through which a client can discover the region and
+// retry against it, which is how the aws sdks recover from the mismatch.
+func Authentication_credentials_incorrect_region_head(s *S3Conf) error {
+	testName := "Authentication_credentials_incorrect_region_head"
+	cfg := *s
+	if cfg.awsRegion == "us-east-1" {
+		cfg.awsRegion = "us-west-1"
+	} else {
+		cfg.awsRegion = "us-east-1"
+	}
+	return authHandler(&cfg, &authConfig{
+		testName: testName,
+		path:     getBucketName(),
+		method:   http.MethodHead,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+
+		expected := s3err.MalformedAuth.IncorrectRegion(s.awsRegion, cfg.awsRegion)
+		if resp.StatusCode != expected.BaseError().HTTPStatusCode {
+			return fmt.Errorf("expected response status code to be %v, instead got %v",
+				expected.BaseError().HTTPStatusCode, resp.StatusCode)
+		}
+
+		return checkRegionMismatchHeader(resp, expected)
+	})
+}
+
+func Authentication_credentials_invalid_date(s *S3Conf) error {
+	testName := "Authentication_credentials_invalid_date"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=[^,]+,")
+		hdr := regExp.ReplaceAllString(authHdr, "Credential=access/3223423234/us-east-1/s3/aws4_request,")
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.InvalidDateFormat("", "3223423234"))
+	})
+}
+
+func Authentication_credentials_future_date(s *S3Conf) error {
+	testName := "Authentication_credentials_future_date"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now().Add(time.Duration(5) * 24 * time.Hour),
+	}, func(req *http.Request) error {
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return err
+		}
+
+		var errResp APIErrorResponse
+		err = xml.Unmarshal(body, &errResp)
+		if err != nil {
+			return err
+		}
+
+		if resp.StatusCode != http.StatusForbidden {
+			return fmt.Errorf("expected response status code to be %v, instead got %v", http.StatusForbidden, resp.StatusCode)
+		}
+		if errResp.Code != "RequestTimeTooSkewed" {
+			return fmt.Errorf("expected error code to be %v, instead got %v", "RequestTimeTooSkewed", errResp.Code)
+		}
+
+		return nil
+	})
+}
+
+func Authentication_credentials_past_date(s *S3Conf) error {
+	testName := "Authentication_credentials_past_date"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now().Add(time.Duration(-5) * 24 * time.Hour),
+	}, func(req *http.Request) error {
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+		body, err := io.ReadAll(resp.Body)
+		if err != nil {
+			return err
+		}
+
+		var errResp APIErrorResponse
+		err = xml.Unmarshal(body, &errResp)
+		if err != nil {
+			return err
+		}
+
+		if resp.StatusCode != http.StatusForbidden {
+			return fmt.Errorf("expected response status code to be %v, instead got %v", http.StatusForbidden, resp.StatusCode)
+		}
+		if errResp.Code != "RequestTimeTooSkewed" {
+			return fmt.Errorf("expected error code to be %v, instead got %v", "RequestTimeTooSkewed", errResp.Code)
+		}
+
+		return nil
+	})
+}
+
+func Authentication_credentials_non_existing_access_key(s *S3Conf) error {
+	testName := "Authentication_credentials_non_existing_access_key"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		accessKeyID := "a_rarely_existing_access_key_id_a7s86df78as6df89790a8sd7f"
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=([^/]+)")
+		hdr := regExp.ReplaceAllString(authHdr, "Credential="+accessKeyID)
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetInvalidAccessKeyIdErr(accessKeyID))
+	})
+}
+
+func Authentication_missing_date_header(s *S3Conf) error {
+	testName := "Authentication_missing_date_header"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		req.Header.Set("X-Amz-Date", "")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetAPIError(s3err.ErrMissingDateHeader))
+	})
+}
+
+func Authentication_invalid_date_header(s *S3Conf) error {
+	testName := "Authentication_invalid_date_header"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		req.Header.Set("X-Amz-Date", "03032006")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetAPIError(s3err.ErrMissingDateHeader))
+	})
+}
+
+func Authentication_date_mismatch(s *S3Conf) error {
+	testName := "Authentication_date_mismatch"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		testuser := getUser("user")
+		err := createUsers(s, []user{testuser})
+		if err != nil {
+			return err
+		}
+
+		authHdr := req.Header.Get("Authorization")
+		regExp := regexp.MustCompile("Credential=[^,]+,")
+		hdr := regExp.ReplaceAllString(authHdr, fmt.Sprintf("Credential=%s/20250912/us-east-1/s3/aws4_request,", testuser.access))
+		req.Header.Set("Authorization", hdr)
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.MalformedAuth.DateMismatch())
+	})
+}
+
+func Authentication_invalid_sha256_payload_hash(s *S3Conf) error {
+	testName := "Authentication_invalid_sha256_payload_hash"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodPut,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+		path:     "bucket/object",
+	}, func(req *http.Request) error {
+		req.Header.Set("X-Amz-Content-Sha256", "invalid_sha256")
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetInvalidArgumentErr(s3err.InvalidArgSHA256Payload, "invalid_sha256"))
+	})
+}
+
+func Authentication_incorrect_payload_hash(s *S3Conf) error {
+	testName := "Authentication_incorrect_payload_hash"
+	const incorrectPayloadHash = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b854"
+	return authHandler(s, &authConfig{
+		testName:       testName,
+		method:         http.MethodPut,
+		body:           nil,
+		service:        "s3",
+		date:           time.Now(),
+		path:           "bucket/object?tagging",
+		overrideSha256: incorrectPayloadHash,
+	}, func(req *http.Request) error {
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetContentSHA256MismatchErr(incorrectPayloadHash, emptySHA256Hash))
+	})
+}
+
+func Authentication_unsigned_required_header(s *S3Conf) error {
+	testName := "Authentication_unsigned_required_header"
+	return actionHandler(s, testName, func(_ *s3.Client, bucket string) error {
+		req, err := createSignedReq(http.MethodPut, s.endpoint, fmt.Sprintf("%s/obj", bucket), s.awsID, s.awsSecret, "s3", s.awsRegion, "", nil, time.Now(), nil)
+		if err != nil {
+			return err
+		}
+
+		req.Header.Set("X-Amz-Copy-Source", "source-bucket/source-key")
+		req.Header.Set("X-Amz-Tagging", "a=b")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetHeadersNotSignedErr([]string{"x-amz-copy-source", "x-amz-tagging"}))
+	})
+}
+
+func Authentication_unsigned_non_required_header(s *S3Conf) error {
+	testName := "Authentication_unsigned_non_required_header"
+	return actionHandler(s, testName, func(_ *s3.Client, bucket string) error {
+		req, err := createSignedReq(http.MethodPut, s.endpoint, fmt.Sprintf("%s/obj", bucket), s.awsID, s.awsSecret, "s3", s.awsRegion, "", nil, time.Now(), nil)
+		if err != nil {
+			return err
+		}
+
+		req.Header.Set("Content-Type", "text/plain")
+		req.Header.Set("X-Custom-Header", "value")
+		req.Header.Set("X-Another-Custom-Header", "value")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+		defer resp.Body.Close()
+
+		if resp.StatusCode != http.StatusOK {
+			return fmt.Errorf("expected response status code to be %v, instead got %v", http.StatusOK, resp.StatusCode)
+		}
+
+		return nil
+	})
+}
+
+func Authentication_signature_error_incorrect_secret_key(s *S3Conf) error {
+	testName := "Authentication_signature_error_incorrect_secret_key"
+	cfg := *s
+	cfg.awsSecret = s.awsSecret + "a"
+	return authHandler(&cfg, &authConfig{
+		testName: testName,
+		method:   http.MethodGet,
+		body:     nil,
+		service:  "s3",
+		date:     time.Now(),
+	}, func(req *http.Request) error {
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		return checkHTTPResponseApiErr(resp, s3err.GetAPIError(s3err.ErrSignatureDoesNotMatch))
+	})
+}
+
+func Authentication_sigv2_not_supported(s *S3Conf) error {
+	testName := "Authentication_sigv2_not_supported"
+	bucket := getBucketName()
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodPut,
+		service:  "s3",
+		date:     time.Now(),
+		path:     fmt.Sprintf("%s/object", bucket),
+	}, func(req *http.Request) error {
+		err := setup(s, bucket)
+		if err != nil {
+			return err
+		}
+
+		req.Header.Del("Authorization")
+		req.Header.Set("Authorization", "AWS seed_signature")
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		if err := checkHTTPResponseApiErr(resp, s3err.GetAPIError(s3err.ErrUnsupportedAuthorizationMechanism)); err != nil {
+			return err
+		}
+
+		return teardown(s, bucket)
+	})
+}
+
+func Authentication_with_expect_header(s *S3Conf) error {
+	testName := "Authentication_with_expect_header"
+	bucket, object := getBucketName(), "object"
+	return authHandler(s, &authConfig{
+		testName: testName,
+		method:   http.MethodPut,
+		body:     []byte("dummy data"),
+		service:  "s3",
+		date:     time.Now(),
+		path:     fmt.Sprintf("%s/%s", bucket, object),
+		headers: map[string]string{
+			"Expect": "100-continue",
+		},
+	}, func(req *http.Request) error {
+		err := setup(s, bucket)
+		if err != nil {
+			return err
+		}
+
+		resp, err := s.httpClient.Do(req)
+		if err != nil {
+			return err
+		}
+
+		if resp.StatusCode != 200 {
+			return fmt.Errorf("expected the response status to be 200, instead got %v", resp.StatusCode)
+		}
+
+		err = teardown(s, bucket)
+		return err
+	})
+}