Java Download Checksum
Joelle Harriage
I think I see your problem. It's with the key of HTTP/RANGER_FQDN principal. Most probably, the key of Ranger SPNEGO principal (HTTP/RANGER_FQDN) has been changed/updated in Kerberos database but not in the spnego.service.keytab on Ranger node. Hence "checksum failed" error.
The fix as of today consists in using google mirror of Maven central. However using this mirror, I get checksum validation failures in some of my builds. This include, for instance, the preesm/graphiti project, with :
Could not transfer artifact org.apache.maven.reporting:maven-reporting-impl:pom:2.3 from/to google-maven-central ( -download.googleapis.com/maven-central/repos/central/data/): Checksum validation failed, no checksums available -> [Help 1]
A checksum hash is an encrypted sequence of characters obtained after applying specific algorithms and manipulations on user-provided content. In this Java hashing tutorial, we will learn to generate the checksum hash for the files.
Checksum acts like a proof of the validity of a file so if a file gets corrupted this checksum will change and thus let us know that this file is not the same file or the file has been compromised between the transfer for any reason.
A checksum is one of the techniques that is used to detect error(s) in the message. We generally use the checksum in the network layer as well as in the transport layer of the TCP/IP protocol suite for error detection. The procedure or the process that generated the checksum of given data input is called the checksum function or checksum algorithm.A checksum helps us in detecting whether a complete message is received or not. The checksum can detect the integrity of our data but it cannot detect the authenticity of the data.
Before learning about implementing checksum using Java, let us get a brief introduction to Java and the TCP/IP model as both of them are a prerequisite for learning about the checksum.
Let us now learn about checksum in Java. A checksum is one of the techniques that is used to detect error(s) in the message. We generally use the checksum in the network layer as well as in the transport layer of the TCP/IP protocol suite for error detection. In these layers, the original data is added with headers, and trailer and then transferred. We also perform encoding and decoding of the data package. Now there is a chance of data loss or changing of the data bit. So, to deal with such scenarios, we use the checksum bit. In this article, we will learn about implementing checksum using Java.
A checksum is applied both at the sending end and at the receiving end to check if the data is correct or not. Now, the checksum can detect the integrity of our data but it cannot detect the a**uthenticity of the data**.
A checksum is the representation of the binary stream of data in a very minimal manner. The procedure or the process that generated the checksum of given data input is called the checksum function or checksum algorithm. We have several algorithms that are commonly used for creating a checksum for example Adler32 and CRC32 algorithms. The algorithms convert a sequence of data into a smaller sequence of data having numbers and letters so that the transmission can be easier.
To generate a checksum for the string or byte array data, we first need to get the data input into the checksum algorithm i.e. CRC32. For the string type data, we have a function called getBytes() that can be used to get a byte array data from a string. This method loads every byte of the data into the memory hence it takes memory.
Now as we have the data in the form of a byte array, we can use the function of the Checksum class like update and getValue to calculate the checksum of the data.
As we have discussed above that a checksum is nothing but a small-sized datum (a single symbol of data or unary data) that is a part of the block of digital data which can be used to detect the errors introduced in the transmission or storage of the data.
In the above code, we have a Test class and first, we are getting the input string to be converted into checksum. We have a function called generateCheckSum() for converting the input into a checksum. We are calling the function and passing the input string. Similarly, we are the data to be sent to the receiver and the checksum to be sent to the receiver.
Now, we are passing the generated checksum and input string to the receive() function. Let us now look at the functioning of the generateCheckSum() function and the receive() function.
In this function, we are first initializing an empty hexadecimal string for storing the checksum. Now, we will be iterating through the input data string and for each character of the string, we are generating a checksum value and appending it to the resultant checksum.
We have another function called generateComplement(). This function is used for generating complement by adding FFFF to the input checksum and then parsing the entire data into an integer.
df19127ead