func doesPolicySignatureV2Match(formValues http.Header) (auth.Credentials, APIErrorCode) {
	accessKey := formValues.Get(xhttp.AmzAccessKeyID)

	r := &http.Request{Header: formValues}
	cred, _, s3Err := checkKeyValid(r, accessKey)
	if s3Err != ErrNone {
		return cred, s3Err
	}
	policy := formValues.Get("Policy")
	signature := formValues.Get(xhttp.AmzSignatureV2)

	if s3Err != ErrNone {
		return auth.Credentials{}, s3Err
	}

	r := &http.Request{Header: formValues}
	cred, _, s3Err := checkKeyValid(r, credHeader.accessKey)
	if s3Err != ErrNone {
		return cred, s3Err
	}

	// Get signing key.
	signingKey := getSigningKey(cred.SecretKey, credHeader.scope.date, credHeader.scope.region, serviceS3)

	extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
	if errCode != ErrNone {
		return cred, "", "", time.Time{}, errCode
	}

	cred, _, errCode = checkKeyValid(r, signV4Values.Credential.accessKey)
	if errCode != ErrNone {
		return cred, "", "", time.Time{}, errCode
	}

	// Verify if region is valid.
	region = signV4Values.Credential.scope.region