Calculate hash for stdin or a file in Windows Console.

1. Download exe file.
2. Copy to C:\Program_Files\Scripts.
3. Add C:\Program_Files\Scripts to PATH environment variable.

about

A hash is like a signature for data, and thus is used to distingush different chunks of data (or files). This distinction can be:

• Space wise, say between 2 different files.
• Time wise, say between the same file some time ago, and now.

The resulting hash value is a number (usually very large) generated from the input data is designed such that very similar, but different data have completely different hash values, making them easily distinguishable by eye. To be clear, these hash values cannot be used to generate / extract the actual data, and are not useful without it.

There exist a few popular hash functions (yes, they are very similar to math functions used in class to generate an output value from multiple input values) that can be used to generate hash values:

• MD5 (Merkle-Damgård 5) 128-bit hash function by Ronald Rivest.
• RIPEMD160 (RACE Integrity Primitives Evaluation Message Digest) 160-bit hash function by Hans Dobbertin, Antoon Bosselaers and Bart Preneel.
• SHA1 (Secure Hash Algorithm 1) 160-bit hash function by NSA.
• SHA256 (Secure Hash Algorithm 2) 256-bit hash function by NSA.
• SHA384 (Secure Hash Algorithm 2) 384-bit hash function by NSA.
• SHA512 (Secure Hash Algorithm 2) 512-bit hash function by NSA.

There exist a few others as well, but they are not currently accepted by this program. It is indeed quite surprising to see NSA's hash algorithms are being used in several places despite the fact that, breaking security is what they do. Despite the fact that these algorithms are quite complex, hash algorithms can in principle be pretty simple like:

hash = XOR of all bytes in data

As can be seen, such a hash value is always 1 byte, no matter what the size of the original data be. Thus by definition, this function is a hash function too! It is simple functions like these, that are used to create hash tables for accessing data by using any value as index of an array, in all programming languages. Go ahead and create your own!

usage

> ehash [-a|--algorithm <algorithm>] [-s|--spaced] [-i|--input <input file>]

:: [] -> optional argument
:: <> -> argument value

:: get md5 hash of a ehash.exe
> ehash --input ehash.exe

:: get md5 hash of a ehash.exe (alternate)
> cat ehash.exe | ehash

:: get sha256 hash of assignment.docx
> ehash --algorithm SHA256 -i assignment.docx

:: get ripemd160 hash of class notes.pdf
> ehash -a RIPEMD160 -i "class notes.pdf"

:: get spaced sha1 hash of star wars.mp4
> cat "star wars.mp4" | ehash -a SHA1 --spaced