Online MD5 Hash Generator

I have the following use case:

• Read n bytes from a file
• Compute (MD5) hash for these n bytes
• Read next m bytes from file
• Compute (MD5) hash for the file up to n+m bytes

Incrementally hashing a file isn't the problem, just call TransformBlock and TransformFinalBlock.

The problem is that I need multiple hashes of data that shares its beginning bytes, but after I have called TransformFinalBlock to read the Hash of the first n bytes I cannot continue to hash with the same object and need a new one.

Searching for the problem, I saw that both Python as well as OpenSSL have an option to copy a hashing object for exactly this purpose:

hash.copy()

Return a copy (“clone”) of the hash object. This can be used to efficiently compute the digests of strings that share a common initial substring.

EVP_MD_CTX_copy_ex() can be used to copy the message digest state from in to out. This is useful if large amounts of data are to be hashed which only differ in the last few bytes. out must be initialized before calling this function.

Searching as I may, I can't find anything withing the stock C# HashAlgorithm that would allow me to effectively Clone() == copy such an object before calling its TransformFinalBlock method -- and afterwards continue to hash the rest of the data with the clone.

I found a C# reference implementation for MD5 that could be trivially adapted to support cloning(*) but would strongly prefer to use what is there instead of introducing such a thing into the codebase.

(*) Indeed, as far as I understand, any Hashing Algorithm (as opposed to encryption/decryption) I've bothered to check is trivially copyable because all the state such an algorithm has is a form of a digest.

So am I missing something here or does the standard C#/.NET interface in fact not offer a way to copy the hash object?

Another data point:

Microsoft's own native API for crypto services has a function CryptDuplicateHash, the docs of which state, quote:

The CryptDuplicateHash function can be used to create separate hashes of two different contents that begin with the same content.

Been around since Windows XP. :-|

Note wrt. MD5: The use case is not cryptographically sensitive. Just reliable file checksumming.

in C# I'm trying to get a hashed md5 value of a password like so:

 string sb = textBox2.Text;            byte[] asciiBytes = ASCIIEncoding.ASCII.GetBytes(sb);            byte[] hashedBytes = MD5CryptoServiceProvider.Create().ComputeHash(asciiBytes);            string hashedString = BitConverter.ToString(hashedBytes).Replace("-", "").ToLower(); var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(sb);            sb = System.Convert.ToBase64String(plainTextBytes);

in php I get that value by using md5 command,

echo md5("megusia94");

the input in both cases are the same,yet the output in PHP is: d1e44ad921daadaf8defadcd21c8644awhile in C# the output is: bWVndXMpYTk0

What am I doing wrong? I've searched this forum and tried:MD5 hashing does not match in C# and PHPc# md5 and php md5 not match

I want to ask how to change password for logged in user,I can change the password when I enter password that matches anyone in database.For just example, user have "admin" password, I just enter the current password,new password and confirm password.

Current password: adminNew Password: newadminCurrent Password: new admin

And also I don't know how to change the password if the passworduses md5(). I hope you can help me, I am a newbie on Codeigniter.I search answers but I really don't understand it so I want to comment but it's required 50 reputation so I post new question.

Here's my code :

Controller

    public function update(){    $this->form_validation->set_rules('password', 'Current Password', 'required|alpha_numeric|min_length[6]|max_length[20]');    $this->form_validation->set_rules('newpass', 'New Password', 'required|alpha_numeric|min_length[6]|max_length[20]');    $this->form_validation->set_rules('confpassword', 'Confirm Password', 'required|alpha_numeric|min_length[6]|max_length[20]');    if($this->form_validation->run()){        $cur_password = $this->input->post('password');        $new_password = $this->input->post('newpass');        $conf_password = $this->input->post('confpassword');        $this->load->model('queries');        $userid = '1';        $passwd = $this->queries->getCurrPassword($userid);        if($passwd->password == $cur_password){            if($new_password == $conf_password){                if($this->queries->updatePassword($new_password, $userid)){                    echo 'Password updated successfully';                }                else{                    echo 'Failed to update password';                }            }            else{                echo 'New password & Confirm password is not matching';            }        }        else{            echo'Sorry! Current password is not matching';    }}else{    echo validation_errors();}

model

 public function getCurrPassword($userid){  $query = $this->db->where(['id'=>$userid])                    ->get('users');    if($query->num_rows() > 0){        return $query->row();    } }  public function updatePassword($new_password, $userid){  $data = array(      'password'=> $new_password      );      return $this->db->where('id', $userid)                      ->update('users', $data); }

in objective-c, We can encrypt a string with md5 by the following codes

const char *cStr = [someString UTF8String];unsigned char result[16];CC_MD5( cStr, strlen(cStr), result );md5String = [NSString stringWithFormat:        @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",        result[0], result[1], result[2], result[3],        result[4], result[5], result[6], result[7],        result[8], result[9], result[10], result[11],        result[12], result[13], result[14], result[15]        ];

but now CC_MD5 dosn't work in swift.How to deal this.

I am trying to get MD5 hash of my data (image downloaded from the interweb). Unfortunately I have upgraded the framework to swift 3 and the method I have been using doesn't work now.

I have converted most of it but I am unable to get bytes out of the data:

import Foundationimport CommonCryptostruct MD5 {    static func get(data: Data) -> String {        var digest = [UInt8](repeating: 0, count: Int(CC_MD5_DIGEST_LENGTH))        CC_MD5(data.bytes, CC_LONG(data.count), &digest)        var digestHex = ""        for index in 0..<Int(CC_MD5_DIGEST_LENGTH) {            digestHex += String(format: "%02x", digest[index])        }        return digestHex    }}

the CommonCrypto is already imported as a custom module. Problem is I am getting 'bytes' is unavailable: use withUnsafeBytes instead on CC_MD5(data.bytes,...

So the question really is, how do I get the bytes out of the data and will this solution work?