protected String createStringToSign(String canonicalRequest,
            AWS4SignerRequestParams signerParams) {

        final StringBuilder stringToSignBuilder = new StringBuilder(
                signerParams.getSigningAlgorithm());
        stringToSignBuilder.append(LINE_SEPARATOR)
                .append(signerParams.getFormattedSigningDateTime())
                .append(LINE_SEPARATOR)
                .append(signerParams.getScope())
                .append(LINE_SEPARATOR)
                .append(BinaryUtils.toHex(hash(canonicalRequest)));

        final String stringToSign = stringToSignBuilder.toString();

        if (log.isDebugEnabled())
            log.debug("AWS4 String to Sign: '\"" + stringToSign + "\"");

        return stringToSign;
    }
protected String createStringToSign ( String canonicalRequest , AWS4SignerRequestParams signerParams ) { final StringBuilder stringToSignBuilder = new StringBuilder ( signerParams . getSigningAlgorithm ( ) ) ; stringToSignBuilder . append ( LINE_SEPARATOR ) . append ( signerParams . getFormattedSigningDateTime ( ) ) . append ( LINE_SEPARATOR ) . append ( signerParams . getScope ( ) ) . append ( LINE_SEPARATOR ) . append ( BinaryUtils . toHex ( hash ( canonicalRequest ) ) ) ; final String stringToSign = stringToSignBuilder . toString ( ) ; if ( log . isDebugEnabled ( ) ) log . debug ( "AWS4 String to Sign: '\"" + stringToSign + "\"" ) ; return stringToSign ; }
Step 2 of the AWS Signature version 4 calculation. Refer to
http://docs.aws
.amazon.com/general/latest/gr/sigv4-create-string-to-sign.html.