Hi, 

This is my code to upload File to s3 bucket.

public with sharing class AWS_File_Upload_Ctrl {

    public static String testIntegration(String filename, String base64Data , String contentType) {
        System.debug('filename---->>'+filename);
        System.debug('base64Data---->>'+base64Data);
        System.debug('contentType---->>'+contentType);
        Blob beforeblob = EncodingUtil.base64Decode(base64Data);
        //Blob beforeblob = Blob.valueOf(base64Data);
        
        String attachmentBody = EncodingUtil.base64Encode(beforeblob);
        String formattedDateString = Datetime.now().formatGMT('EEE, dd MMM yyyy HH:mm:ss z');
        String key = 'AKIAJNWEGTHJFMQQLPBA';
        String secret = '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';
        String bucketname = 'personalsfbucket';
        String foldername = 'DocumentUploaded';
        String host = 's3.ap-south-1.amazonaws.com';
        String method = 'PUT';

        HttpRequest req = new HttpRequest();
        req.setMethod(method);
        req.setEndpoint('https://' + bucketname + '.' + host + '/' + fileName); //('https://' + host + '/' + bucketname + '/' + filename);
        req.setTimeout(120000);
        req.setHeader('Host', bucketname + '.' + host);
        req.setHeader('Content-Length', String.valueOf(attachmentBody.length()));
        req.setHeader('Content-Encoding', 'base64');
        req.setHeader('Content-type', contentType);
        req.setHeader('Connection', 'keep-alive');
        req.setHeader('Date', formattedDateString);
        req.setHeader('ACL', 'public-read');
        req.setBodyAsBlob(beforeblob);
        System.debug('req---->'+req);
        /* String stringToSign = 'PUT\n\n' +
                contentType + '\n' +
                formattedDateString + '\n' +
                '/' + bucketname + '/' + bucketname + '/' + filename; */

        String stringToSign = 'PUT\n' +
                contentType + '\n' +
                formattedDateString + '\n' +
                '/' + bucketname + '/' + bucketname + '/' + filename;
        System.debug('stringToSign---->>'+stringToSign);

        String encodedStringToSign = EncodingUtil.urlEncode(stringToSign, 'UTF-8');
        Blob mac = Crypto.generateMac('HMACSHA1', blob.valueof(stringToSign),blob.valueof(secret));
        String signed = EncodingUtil.base64Encode(mac);
        String authHeader = 'AWS' + ' ' + key + ':' + signed;
        System.debug('authHeader---->>'+authHeader);
        req.setHeader('Authorization',authHeader);
        String decoded = EncodingUtil.urlDecode(encodedStringToSign , 'UTF-8');

        Http http = new Http();
        HTTPResponse res = http.send(req);
        System.debug('RESPONSE STRING: ' + res.toString());
        System.debug('RESPONSE STATUS: ' + res.getStatus());
        System.debug('STATUS_CODE: ' + res.getStatusCode());
        if(res.getStatusCode() == 200){
            String ReturnUrl = 'https://'+host+'/'+bucketname+'/'+bucketname+'/'+filename;
            System.debug('ReturnUrl---->>'+ReturnUrl);
            return ReturnUrl;
        }
        return 'ERROR';
    }
}

I am getting error message while runing it through Anonymous Window:

System.HttpResponse[Status=Bad Request, StatusCode=400]

Please Help:(

Thanks in advance:)