Online SHA256 Hash Generator

I want to get sha2 hash of particular java object. I don't want it to be int, I want byte[] or at least String. I've got the following code to create sha2:

static byte[] sha2(byte[] message) {    if (message == null || message.length == 0) {        throw new IllegalArgumentException("message is null");    }    try {        MessageDigest sha256 = MessageDigest.getInstance(SHA_256);        return sha256.digest(message);    } catch (NoSuchAlgorithmException e) {        throw new IllegalArgumentException(e);    }}

I can just convert my object to byte[], but I don't think it's a good idea to store big array in memory just to create 32 byte array. So how can I compute sha2(or maybe another crypto hash function) of object?

I have some string and I want to hash it with the SHA-256 hash function using C#. I want something like this:

 string hashString = sha256_hash("samplestring");

Is there something built into the framework to do this?

I have two different csv-files with 3 columns (SHA256hash,path+filename,date), i have to know witch hashes match in these files. Is there a simple way to do this with sed/grep/awk?

Example file:

A7F68D4D0B6718BFFACD27BDD24AA3F8D3BBC89D73293CBBAE61F157C8134E5E;/home/user/file1;07.10.2017 15:16:17 F31482DBEDD54E03A40C3AEE68FB8526A5DECD4159847D97B37B0B8338A31B46;/home/user/file2;30.10.2017 16:09:05 80145B8DF148B15223C6ACA28A3AE8F49FD58B1618893A46F3DA4A3C7701E983;/home/user/file3;20.01.2011 14:58:30

Im a student and this is for educational purpose:I've created a class where you can update (create a new) password for a user. This is my first time using encryption and I have some problems in this regards. The password is hashed and salt is stored. But when i try to log in with a hashed and salted user, I simply get access denied because its wrong username/password.

Login code:

    private bool UserExists(string Username, string Password)    {        using (var con = new MySqlConnection(_connectionString))        {            con.Open();            MySqlCommand cmd = con.CreateCommand();            cmd.CommandType = CommandType.Text;            cmd.CommandText =                @"SELECT *                     FROM user                   WHERE username= @username                   AND password= @password";            cmd.Parameters.AddWithValue("@username", bxUserName.Text);            cmd.Parameters.AddWithValue("@password", bxPassword.Text = GenerateSHA256Hash(bxPassword.Text, salt));            cmd.ExecuteNonQuery();            DataTable dt = new DataTable();            MySqlDataAdapter da = new MySqlDataAdapter(cmd);            da.Fill(dt);            using (var reader = cmd.ExecuteReader())            {                return (reader.Read());            }        }    }

I have reused GenerateSHA256Hash() and CreateSalt() in the login form.

Code for where i hash password:

    private void updatePassword()    {        String salt = CreateSalt(10);        String hashedpassword = GenerateSHA256Hash(txtPassword.Text, salt);        using (var con = new MySqlConnection(_connectionString))        {            con.Open();            MySqlCommand cmd = con.CreateCommand();            cmd.CommandType = CommandType.Text;            cmd.CommandText =                @"UPDATE user                    SET password=@password, salt=@salt WHERE username= @username";            cmd.Parameters.AddWithValue("@password", txtPassword.Text = GenerateSHA256Hash(txtPassword.Text, salt));             cmd.Parameters.AddWithValue("@salt", txtPassword.Text = salt);             cmd.Parameters.AddWithValue("@username", txtUserName.Text);            cmd.ExecuteNonQuery();            lblEditPW.Show();          }      }    public String GenerateSHA256Hash(String input, String salt)    {        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(input + salt);        System.Security.Cryptography.SHA256Managed sha256hashstring =             new System.Security.Cryptography.SHA256Managed();        byte[] hash = sha256hashstring.ComputeHash(bytes);        var sb = new StringBuilder();        foreach (byte b in hash) sb.AppendFormat("{0:x2}", b);        return sb.ToString();    }    public String CreateSalt(int size)    {        RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider();         byte[] buffer = new byte[8];        rng.GetBytes(buffer);        string salt = BitConverter.ToString(buffer);        return Convert.ToBase64String(buffer);    }

I am working on an encryption method in the iPhone with the RSA encryption method, so far i could achieve getting the encryption string with this method, the string is successfully decrypted by the server.

SecKeyRef keyRef = [self addPublicKey:pubKey];SecKeyAlgorithm algorithm = kSecKeyAlgorithmRSAEncryptionOAEPSHA256;if (!keyRef) {    return nil;}BOOL canEncrypt =  SecKeyIsAlgorithmSupported(keyRef, kSecKeyOperationTypeEncrypt, algorithm);if (canEncrypt) {    CFErrorRef error = NULL;    NSData *encryptedData = (NSData *)CFBridgingRelease(                                                        SecKeyCreateEncryptedData(keyRef, algorithm, (__bridge CFDataRef) content, &error)    );    if (encryptedData) {        return encryptedData;    }else{        NSError *err = CFBridgingRelease(error);        NSLog(@"Ocurrió un error %@", err.localizedDescription);        return nil;    }}

This method works for ios 10 and newer, what i need is to know how to set the algorithm in prior ios versions, my code is the following

SecKeyRef keyRef = [self addPublicKey:pubKey];if (!keyRef) {    return nil;}size_t cipherBufferSize = SecKeyGetBlockSize(keyRef);uint8_t *cipherBuffer = malloc(cipherBufferSize * sizeof(uint8_t));memset((void *)cipherBuffer, 0*0, cipherBufferSize);NSData *plainTextBytes = content;size_t blockSize = cipherBufferSize - 11;size_t blockCount = (size_t)ceil([plainTextBytes length] / (double)blockSize);NSMutableData *encryptedData = [NSMutableData dataWithCapacity:0];for (int i=0; i<blockCount; i++) {    int bufferSize = (int)MIN(blockSize,[plainTextBytes length] - i * blockSize);    NSData *buffer = [plainTextBytes subdataWithRange:NSMakeRange(i * blockSize, bufferSize)];    OSStatus status = SecKeyEncrypt(keyRef,                                    kSecPaddingOAEP,                                    (const uint8_t *)[buffer bytes],                                    [buffer length],                                    cipherBuffer,                                    &cipherBufferSize);    if (status == noErr){        NSData *encryptedBytes = [NSData dataWithBytes:(const void *)cipherBuffer length:cipherBufferSize];        [encryptedData appendData:encryptedBytes];    }else{        if (cipherBuffer) {            free(cipherBuffer);        }        return nil;    }}if (cipherBuffer) free(cipherBuffer);

So far i can see that in the version of ios 10 you can set the algorithm with this line

SecKeyAlgorithm algorithm = kSecKeyAlgorithmRSAEncryptionOAEPSHA256;

my question is, how do i get that algorithm in the early version of ios, the second code i post can't be decrypted.

Thanks for your help