return auth.Credentials{}, false, ErrMissingFields
		}
		ch, s3Err = parseCredentialHeader(authFields[0], region, stype)
		if s3Err != ErrNone {
			return auth.Credentials{}, false, s3Err
		}
	}
	return checkKeyValid(r, ch.accessKey)
}

// parse credentialHeader string into its structured form.
func parseCredentialHeader(credElement string, region string, stype serviceType) (ch credentialHeader, aec APIErrorCode) {

				sampleTimeStr,
				"us-west-1",
				"s3",
				"aws4_request"),
			expectedErrCode: ErrNone,
		},
	}

	for i, testCase := range testCases {
		actualCredential, actualErrCode := parseCredentialHeader(testCase.inputCredentialStr, "us-west-1", "s3")
		// validating the credential fields.
		if testCase.expectedErrCode != actualErrCode {