SHA256 online Hash Generator

Currently I am using SHA256WithRSA to sign and verify signature between our server and third-party's one as below:

import java.security.Signature;import java.security.GeneralSecurityException;...private static final String SIGN_ALGORITHM = "SHA256WithRSA";public static byte[] sign(PrivateKey privateKey, byte[] data) throws GeneralSecurityException {    Signature sign = Signature.getInstance(SIGN_ALGORITHM);    sign.initSign(privateKey);    sign.update(data);    return sign.sign();}public static boolean verify(PublicKey publicKey, byte[] data, byte[] signature) throws GeneralSecurityException  {    Signature sign = Signature.getInstance(SIGN_ALGORITHM);    sign.initVerify(publicKey);    sign.update(data);    return sign.verify(signature);}

Any body know which standard is used for SHA256WithRSA?

Thanks,

I would like to ask your assistance on how to calculate sha256 of large files in PHP. Currently, I used Amazon Glacier to store old files and use their API to upload the archive. Initially, I just used small files that cannot reach to MB-sized images. When I tried to upload more than 1MB, the API response said that the checksum I gave to them is different from what they had calculated.

Here is my code to upload the file:

//get the sha256 using the file path$image = //image path;$sha256 = hash_file("sha256", $image);$archive = $glacier->uploadArchive([            'accountId' => '',             'body' => "",            'checksum' => $sha256,            'contentSHA256' => $sha256,            'sourceFile' => $image,            'vaultName' => 'my-vault'        ]);

And the error:

AWS HTTP error: Client error: `POST https://glacier.us-west-2.amazonaws.com/vaults/70/archives` resulted in a `400 Bad Request` response:{"code":"InvalidParameterValueException","message":"Checksum mismatch: expected 9f1d4da29b6ec24abde48cb65cc32652ff589467 (truncated...)

I tried the function like below to check for the final hash but it seems it's not the right hash when I print it:

private function getFinalHash($file){    $fp = fopen($file, "r");    $ctx = hash_init('sha256');    while (!feof($fp)) {        $buffer = fgets($fp, 1024);        hash_update($ctx, $buffer);    }    $hash = hash_final($ctx, true); print_r($hash);exit;    fclose($fp);}

The resulted hash is like this: ŸM¢›nÂJ½äŒ¶\Ã&RÿX”gíÖ'„IoA\C÷×

The Amazon Glacier API documentation shows how to compute the checksum as stated:

For each 1 MB chunk of payload data, compute the SHA-256 hash. The last chunk of data can be less than 1 MB. For example, if you are uploading a 3.2 MB archive, you compute the SHA-256 hash values for each of the first three 1 MB chunks of data, and then compute the SHA-256 hash of the remaining 0.2 MB data. These hash values form the leaf nodes of the tree.

I think there has something to with the correct way in providing the checksum but I don't know how I should do it with large files using PHP. I really need your help regarding this one.

I found an implementation of SHA256 on the net. It consists of a single file sha256.c, I've tested the function successfully on Linux.

Here's the link for the file: http://bradconte.com/sha256_c

When I try to use it in contiki, the output is not right.

Here's a piece of the code :

unsigned char text1[]={"sallam"}, hash[32];int idx;SHA256_CTX ctx;sha256_init(&ctx);sha256_update(&ctx, text1, strlen(text1));sha256_final(&ctx, hash);print_hash(hash);

Here's the function I use to print the hash:

void print_hash(unsigned char hash[]){    int idx;    for (idx=0; idx < 32; idx++)       printf("%02x",hash[idx]);    printf("\n");}

I've already tried to change the format ouptut to %x but it didn't help.I think it has something to do with little-endian vs big-endian (endianness) issues.

The code below generates a signed hash using HMAC SHA256. This code compiles and works fine on Debian Jessie and Ubuntu 16.04 (OpenSSL 1.0.2g 1 Mar 2016).

#include <openssl/evp.h>#include <openssl/hmac.h>#include <iomanip>#include <iostream>#include <string>#include <sstream>using namespace std;string HMAC256(string data, string key){        stringstream ss;        HMAC_CTX ctx;        unsigned int  len;        unsigned char out[EVP_MAX_MD_SIZE];        HMAC_Init(&ctx, key.c_str(), key.length(), EVP_sha256());        HMAC_Update(&ctx, (unsigned char*)data.c_str(), data.length());        HMAC_Final(&ctx, out, &len);        HMAC_cleanup(&ctx);         for (unsigned int i = 0;  i < len;  i++)        {          ss << setw(2) << setfill('0') << hex << static_cast<int> (out[i]);        }        return ss.str();}int main(){    cout << HMAC256("AAAA","BBBB") << endl;    return 0;}

HOWEVER....

When compiling it on Debian Stretch I get the following error:

hmac256.cpp: In function ‘std::__cxx11::string HMAC256(std::__cxx11::string, std::__cxx11::string)’:hmac256.cpp:14:18: error: aggregate ‘HMAC_CTX ctx’ has incomplete type and cannot be defined         HMAC_CTX ctx;                  ^~~hmac256.cpp:18:9: warning: ‘int HMAC_Init(HMAC_CTX*, const void*, int, const EVP_MD*)’ is deprecated [-Wdeprecated-declarations]         HMAC_Init(&ctx, key.c_str(), key.length(), EVP_sha256());         ^~~~~~~~~In file included from /usr/include/openssl/hmac.h:13:0,                 from hmac256.cpp:2:/usr/include/openssl/hmac.h:28:1: note: declared here DEPRECATEDIN_1_1_0(__owur int HMAC_Init(HMAC_CTX *ctx, const void *key, int len, ^

And this has to do with the new OpenSSL version (OpenSSL 1.1.0f 25 May 2017).

QUESTION

Why am I experiencing the problem with OpenSSL 1.1, and how to fix it in a way that maintains backward compatibility with OpenSSL 1.0?

I am trying to encrypt a file on Linux using OpenSSL. For cipher I want to use SHA256 bit encryption. This is something new to me and I don't have idea from where should I start.

Can anyone help me? How can I implement this? Please help me with steps or documentation that can help me in achieving this.

Thanks in advance.