Generate checksums for files

This simple (Windows) function uses the certutil function built into Windows for computing the hash of a file from a choice of algorithms.

A file containing the computed hash is generated, the hash is returned, and printed to history - whichever you like.

Function can be called from inside another function, command line, or executed interactively.

In line e.g. String hash = getHash("C:\path\some.file","MD5",quiet=1)

From the command line e.g.: getHash("C:\path\some.file","MD5")

// menu
Menu "Tools"
	"Generate checksum",/Q, getHashManually()
	end

// List of built-in Windows hash functions provided by CertUtil 	
Static StrConstant hashFuncLst="MD2;MD4;MD5;SHA1;SHA256;SHA384;SHA512;"

//___________________________________________________________________________________________________	
// Function to get the hash of an input file (objectStr) output as a text file (eg .md5), a string variable, and printed to history
// Valid values for hashFunc: MD2 MD4 MD5 SHA1 SHA256 SHA384 SHA512
// Synax - cmd.exe /C certutil -hashfile C:\\file.txt MD5 
Function/S getHash(String ObjectStr,String hashFunc[,Variable quiet])

	String fileHash="", LineStr="", PathStr, fexts
	Variable fileID,i
	
	// make the file extension (lowercase)
	fexts=LowerStr(hashFunc)[0,2]
	
	// make sure the path is in windows form
	ObjectStr=ParseFilePath(5, ObjectStr, "\\", 0, 0)
	
	// make a new path in the location of the file to be hashed
	PathStr = ParseFilePath(1, ObjectStr, "\\", 1, 0)
	NewPath /O/Q/Z ObjectPath, PathStr

	// execut cmd script
	ExecuteScriptText/B/Z "cmd.exe /C certutil -hashfile \""+ObjectStr+"\" "+hashFunc 
	
	// read the output from the getHash command
	do
		LineStr = StringFromList(i,S_value, "\n")
		// Success
		if (Stringmatch(lineStr, hashFunc+" hash of "+ ObjectStr +":\r"))
			fileHash = StringFromList(i+1,S_value, "\n")
			
			// make a new hash file without the other CMD lines in it
			open /P=ObjectPath fileID as ParseFilePath(3, ObjectStr, "\\", 0, 0)+"."+fexts
			fprintf fileID, replaceString("\r",StringFromList(i+1,S_value, "\n"),"")
			close fileID
			
			// print output
			if (paramisDefault(quiet))
				Print hashFunc+" hash of "+ParseFilePath(0, ObjectStr, "\\", 1, 0)+": "+fileHash
			endif
			Break
		// Handle other errors	
		else
			if (paramisDefault(quiet))
				Print "There was a problem generating a "+hashFunc+" hash for "+ParseFilePath(0, ObjectStr, "\\", 1, 0)
			endif
			break
		endif
		i+=1
	while (i < ItemsInList(S_value, "\n")) 
	return fileHash            
end
//___________________________________________________________________________________________________	
// Function to allow manual generation of checksum
Function getHashManually()
	
	Open/D/R/MULT=1/F="*"/M="Select files for generating a checksum" fileID
		if(strlen(S_fileName)==0)
			return 0 // user didn't choose a file
		else
			S_filename=replacestring("\r",S_filename,";")
		endif
	
	String hashFunc
	Prompt hashFunc "Choose a checksum method", popup hashFuncLst
	DoPrompt/HELP="" "Checksum generator" hashFunc
		If (V_flag!=0)
			return 0 // user hit cancel
		endif
	
	Variable i
	for (i=0;i<itemsinlist(S_filename);i+=1)
		gethash(stringfromlist(i,S_filename),hashFunc)
	endfor
end
//___________________________________________________________________________________________________