Accelerate The Generation Of The MD5 Checksum?
Mar 17, 2010
I'm working with some very large files residing on P2 (Panasonic) cards. Part of the process we employ is to first generate a checksum of the file we are going to copy, then copy the file, then run a checksum on the file to confirm that it copied OK. The problem is, is that files are large (70 GB+) and take a long time to complete. It's an issue since we will eventually be dealing with thousands of these files.
I would like to find a faster way to generate the checksum other than using the System.Security.Cryptography.MD5CryptoServiceProvider I don't care if this means using a specialized hardware card, provided it works and is not to ungodly expensive. I would prefer to have a method of encoding that provided some feedback as to how far the process has gone along so I can display it like I do now.
The application is written in vb.net. I would prefer to be able to use it as component, library, reference within my application, but I'm willing to call an outside application if there is enough improvement in the speed of generating the checksum.
Needless to say, the checksum must be consistent and correct.
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Feb 23, 2010
This comparison shows the different values of the known good checksum calculation (c#) as used by my client and what I 'hoped' was the vb.net equivalent. How can I get 405 rather than 513 as I currently do?
For i = 0 To length - 2 Step 1
cksum += sendFrameData(i + 5)
Next i
[Code]....
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Nov 30, 2011
I need to convert a string to get a checksum as follows;
Checksum
The checksum is the 8 LSB (least significant bits) of a simple addition of all octets (note that a message type '30' is two octets with the values 33 hex and 30 hex) following the STX character and until the checksum field. Note that all separators will be included in the checksum, but the STX, checksum and the ETX will not be included.
Dim str as string = "01/00064/O/30/12345678/87654321////////48656C6C6F20576F726C64/"
This should result in checksum = "C2" What type of checksum is this? what should I Google for? CRC, MD5, hash ?
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Sep 14, 2009
Dim sum As Byte
Dim Trans_Array(_64K, 2) As Byte
Const _64K As Integer = 65536
sum = 0
For i = 0 To 15
BinaryStream.Write(Trans_Array(Address + i, RIGHT_FILE))
sum = (Convert.ToByte(sum + Trans_Array(Address + i, RIGHT_FILE)))
Next
I can't figure out how to calculate the checksum of the bytes from array.
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Oct 4, 2011
I have the following hex string 40 50 4C 41 59 0D I am transmitting to a piece of equipment, I need to calculate a checksum value to add to the string as the last byte to be sent. The checksum byte is generated in such a manner that the result of addition of all bytes of a message will become 11111111(255). the code that you see here does not work can anyone tell/show me why? Whats important is the checksum calculation.
[Code]...
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Sep 17, 2011
Is it possible for my application to check if its been modified?
e.g. Could i compile the app and use a 3rd party tool to calculate the MD5 checksum of the compiled exe - and inside the app, code it so that if the MD5 checksum doesnt match then run the deactivation process?
I know its not foolproof but if it makes it slightly more hassle to crack my app i'd rather have it
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Mar 24, 2010
Is there any way to generate checksum for a dll from the main app (compiled) and the main app from the dll when I run the main app or something of this kind?
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Sep 22, 2011
I'm trying to create an app that controls a BSS BLU-80 (DSP) through Ethernet. I've written a few basic programs in the past, but nothing that used sockets or even required calculating a checksum. One of the values I need to send has to be 24 bits. This one really has me scratching my head. From the manufacturer's docs:
[Code]...
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Dec 31, 2009
This function doesn't work if I change the input argument 'pdu' from a string to an int.Would someone please help me figure out what to do here so that the checksum does not add the ascii value of the int argument but rather the actual integer value?I took out a few lines of the actual function but it adds the input argument to a packet sent out via TCP protocol.This function shows the integer value just fine in the string that gets encoded as a byte array. the checksum is wrong.!
''Public Function buildpacket(pdu As Integer) is what I want.
Public Function buildpacket(pdu As String)
Dim packet As String
[code]....
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Apr 12, 2012
I've wanting to generate a CRC16-X25 checksum in the form HiByte and LowByte. All the examples I've found by searching are either VB6 which uses functions and data types that are no longer supported or C, C++ etc. Does anyone have a simple VB.Net version? Speed is not an issue.
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Feb 22, 2012
I have been trying to compute the checksum for a line of hex code. This is to create a hex file which will be loaded onto an embedded micro.Some of you guys may not know how this is done so very briefly:
a line of hex bytes:
: 10 01 00 00 21 46 01 36 01 21 47 01 36 00 7E FE 09 D2 19 01 40
The underlined bytes are taken and summed. (in this case the decimal 960). and the bold is the checksum Only the 8LSB (or single least significant byte) is needed to compute the checksum... which in this case, 960 = 03C0 in hex, so only C0 is needed.Two's complement is then taken:
step 1) logical not of C0 which is
step 2) add one (integer)
BIN...........DEC...HEX
[code]....
So here is the code I have been using: (quick mention that in the string passed, the hex bytes are all grouped together, there are no space characters)
Public Sub CreateLine(ByVal Data As String)
'Dim BDataArray(DataLength) As Byte
Dim IDataArray(Data.Length) As Integer
[code]....
where i get into trouble is where i commented 'i get into trouble'. My code works, but it's rather crude Now, in that line i first convert the hex value (string) "SChecksum" into an integer. I want to NOT this, so I get my step 2 from my explanation. However, the results appears to be a signed logical NOT. which gives me the wrong answer. My hashed togther version simply subtracts 256 before the not, in order to give me the correct answer.
Basically, I would love for someone to chime in and point out the flaws in my function, and push me towards figuring out the 'proper' way of doing this. Also I can't quite wrap my head around what would happen in the case a string were passed to my function that is over 16 bits, but I imagine I would have to subtract a larger value than 256, before doing the NOT in this case?(whilst we're on the subject of functions, I've used a 'sub', in which case should I used a sub, and which case should I use a function?).
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Feb 2, 2011
What resources I need to look for, to generate one png image out of three? Since there are sprite generators out there, that do not do what I want, I wanted to try by myself. The user interface should not be the problem, but i have no experience of generating bitmaps, especially those with transparent backgrounds. I will do that in .net. Letīs say I have 6 png files. I want to put them into one image, where there will be two rows of images in it, so 3 in row, 2 in height, 3*2. Every image might have a little different sizes, so i would need to fill up the space with, um, nothing..
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Jan 9, 2010
are there any classes in the .net framework that allow me to generate classes that i can save as .cs or .vb files ?
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May 20, 2010
in vb.net while entering a new entry i want to assign a record a unique id like in case of numeric i do this way
Dim ItemID As Integer
KAYAReqConn.Open()
SQLCmd = New SqlCommand("SELECT ISNULL(MAX(ItemID),0) AS ItemID from MstItem", ReqConn)
[Code]....
in this case m using itemid as a unique id and the format is 1,2,3... and m finding out the max and assigning to a new record but how to assign if the previous id is of the a00001,a00002,a00003,a00004...so on. how i do i produce a unique id in this case
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Apr 11, 2010
I have the following situation: An interface (Windows forms) to a dataset. It has binding navigator, binding source, table adater etc operating with a dataset. How can I make a textbox for an ID field automatically generate an appropriate number for the ID? Just like the sql server direct database editor generates an id for fields with the "is identity" and "auto increment" properties on.
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Dec 12, 2009
I am working on a Point of Sale system using VB express 2008.I want to generate invoice with Barcode and also stock items with Barcodesort of Barcode system i should use for this and also how i can code to generate and pring the Barcod
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Mar 6, 2011
I face problems while transferring objects between layers (mainly the Presentation Layer), as I work with classes having approximately 40 properties.(I don't reference the DAL in the Presentation Layer)So here's what I decided, I am planning to build an App (maybe Visual Studio Addin) which will help noobs like me to build POCO's rapidly.The GUI of the APP would probably be a datagrid with columns for
1) access modifiers
2) property name
3) data type
4) get method (checkbox)
5) set method (checkbox)
Also, the app will have an option to connect to the table and automatically generate a POCO class I would like to generate Strongly typed C# / VB.NET POCO classes for different Scenarios, Like Entity Framework, LLBLgen etc. I am mainly targeting LLBLgen and EntityFramework?I need the following information:
1) Is there such a tool which already exists
2) What are the things that I have to consider (like nullable types etc)
3) The DataTypes generate by ORM's LLBLgen/EF/nHibernate
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Feb 19, 2009
When I close the form I get the message "Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key column information."at line obj_oledb_da.Update(dataSet).
[Code]...
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Jan 13, 2010
i just don't like the gap that exists between the .net framework and SQL database. I've explored everything from EF to LINQ to raw sql command strings.Does anyone know a project acting like a generic editor for a database? Meaning adding tables and relationships and constraints at runtime and offering simple field validation based on the information generated by the database schema. I know you can always drag and drop fields from a datatable to a form and a wizard will give you basic navigation over it, but I was wondering, is there more to it?
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Nov 9, 2009
I have a problem regarding the generation of random numbers in vb.net..I have code like this!!it generates the random number but both the numbers are same for my program the should not be same!![code]
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Sep 19, 2011
I want to call Jasper Reports via VB.net.Is this possible?
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Mar 19, 2012
I have an situation where i need to convert Doc file into PDF file. I am devepoing windows application in vb.net. and also i don't want to user third party dll if possible.
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Jul 7, 2009
I have an MDI form with 3 nested children with in it. As of right now all it can do is display a new form.For example: each time I press the menu button, the new child form(Form1) is created. Now, if I press that same menu button a second or subsequent time a new Form1 is created and it appears over the previous one.
What I would like is that each time the event handler is triggered (a menu item_click on the parent form) that instead of a completely "new" child form being produced(a new window popping up) it would instead pull up the appropriate child form that is attached to the trigger.
[Code]...
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Jul 19, 2011
I am new to WSSF and am wondering if it would work for solution with VB as the programming language if so how to achieve it. I have seen samples which generates C# code but my project requirement is VB .Net.
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Nov 10, 2011
I have a windows form having combobox and textbox controls.. I have to generate a part number, consisting of combobox and textbox values included.. I can explain in detail.. This is the code i have used to define a variable "type"..
[Code]...
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Dec 13, 2011
Dynamic SQL generation for the DeleteCommand is not supported against a SelectCommand that does not return any key column information. above error has occure during updating and deleting the record
Dim constr As String
Dim con As OleDb.OleDbConnection
Dim da As OleDb.OleDbDataAdapter
Dim ds As New DataSet
[code]....
i set the primary key also records are present in database?
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Mar 19, 2010
Getting the following error when running my application.Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key column information.On form load it reads the database to the textboxes for the user, they can then change their details.On clicking the save button I am attempting to update the database with the information from a textbox but the above error is thrown and I'm not a bit lost.[code]
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Oct 13, 2010
Error Which I get is:
"Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key column information."
The Code is as follows:
Dim Countr As Integer
For Countr = 1 To GrdData.RowCount
strTrnsUpdt = "select * from order_transaction where uniq_id='primary key of the field to be updated'"
[Code].....
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Sep 3, 2009
I am working on an Excel report and I would like the top rows to be empty to allow for an image to be inserted. However, I do not want the image size to change the width of the columns and would rather the data below do that.
This is what I have so far:
If ComDset.Tables(0).Rows.Count > 0 Then
Try
[code].....
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May 27, 2011
I just realized the OLD tutorial here is still works. Here is the webpage link But that one is iText 2005. And now is 2011, I wonder if there's any nearest version of iText for vb.net ? didn't found the iText for vb.net in 2008 version.... is there anyone could clarify this?
Because that 2005 version is using .Net framework 1 or 2. Very old... now I'm using version 3 & 4.
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