Online SHA256 Hash Generator

I need to get the sha256 hash of a chunk of a binary file.I wrote a little shell script for that task:

dd if=$1 skip=$2 count=$3 bs=1 | sha256sum

When I test it, I get the following result:

bernardo@bernardo-ThinkCentre-Edge72:~$ ./test.sh test.bin 10 2020+0 records in20+0 records out20 bytes (20 B) copied, 0,000100981 s, 198 kB/s7d9330a7c51eabe36a81a6cff308ac4d2035e63d7a356fc112f4fcd16208f43d  -

Does that mean the hash is based solely on the chunk output by dd, or did it also use dd's feedback "20+0 records in..."?

I'm writing a register form for a application but still having problems with being new to c#.

I am looking to encrypt/hash passwords to md5 or sha-256, preferably sha-256.

Any good examples? I want it to be able to take the information from "string password;" and then hash it and store in the variable "string hPassword;". Any ideas?

I am trying to convert and hash function in java below to c# equivalent

     String mt ="411111111990";     String hash_data="testclient111111222222016-12-26 12:37";     MessageDigest algorithm = MessageDigest.getInstance("SHA-256"); //get the instance of sha256        algorithm.reset();     byte[] key=meterno.getBytes(); //converts the meter number into bytes and read into a byte array       algorithm.update(key);        byte messageDigest[] = algorithm.digest(hash_data.getBytes("UTF-8"));       //convert messageDigest[]  into individual hex nibble.. that is your hash

The Security services API doesn't appear to allow me to compute a hash directly. There are plenty of public domain and liberally licensed versions available, but I'd rather use a system library implementation if possible.

The data is accessible via NSData, or plain pointers.

The cryptographic strength of the hash is important to me. SHA-256 is the minimum acceptable hash size.

In this question it turned out, that I cannot use the sha256 mechanism in the FROM line in a Dockerfile to verify I am using the correct locally built non-DockerHub image in another derived image.

Is there another way to verify locally built Docker images? Some best practice maybe?