How Digital Signatures Work - Win32 Programmer's Reference

Custom Search

How Digital Signatures Work

There are two steps involved in creating a digital signature from a message. The first step involves creating a hash value (also known as a message digest) from the message. This hash value is then signed, using the private key of the signer. Following is an illustration of the steps involved in creating a digital signature:

To verify a signature, both the message and the signature are required. First, a hash value must be created from the message, in the same way as when the signature was created. This hash value is then verified against the signature, using the public key of the signer. If the hash value and the signature match, you can be confident that the message is indeed the one the signer originally signed and that it has not been tampered with. The following diagram illustrates the process involved in verifying a digital signature.

A hash value consists of a small amount of binary data, typically around 160 bits. This is produced using a hashing algorithm. A number of these algorithms are listed later in this section.

All hash values share the following properties, regardless of the algorithm used:

The hash value is of a fixed length, regardless of the size of the message. The message can be several kilobytes or several gigabytes, it doesn't matter. Depending on the algorithm used, the hash value length will generally be either 128 or 160 bits.
Every pair of nonidentical messages will translate into a completely different hash value, even if the two messages differ only by a single bit. Using today's technology, it is not feasible to discover a pair of messages that translate to the same hash value without breaking the hashing algorithm.
All hashing algorithms are fully deterministic. That is, each time a particular message is hashed using the same algorithm, the exact same hash value will be produced.
All hashing algorithms are one-way. Given a hash value, it is not possible to recover the original message. In fact, none of the properties of the original message can be determined given the hash value alone.

Last news from Greatis Software

    Nostalgia .Net     .Net is powerful, but not all-powerful, so sometimes we need to use Win32 API for our .Net applications. It's simple enough with Platform Invoke if you have Win32 skill, but we do not always have time to dig the ancient documentation, declare the special types that are compatible with Win32, find the values of the Win32's constants and so on. Nostalgia .Net offers several simple-to-use classes, and components that will allow you to forget about the headache of Win32 and just use the power of Win32 in your application the same way as you use the native. Net classes. More »

Recommended software for developers

    Ultimate Pack     Component pack for Delphi and C++ Builder that contains runtime form designer, runtime object inspector, print suite and much more for the very special price. More »

    Form Designer .Net     Unique runtime form design solution that allows to edit any form in .Net WinForms application at runtime with full source codes for only 300 euro! More »

    Print Suite .Net     Print Suite .Net is a set of components for easy printing texts, images and grids from your WinForms applications. Full C# source codes are available More »

    Gradient Controls .Net     Gradient Controls .Net offers controls with gradient background feature. Labels, panels and so on... Full C# source codes are available More »

    Greatis iGrid     iGrid plots drawing grid right over your desktop, so you can use it everywhere, with any drawing application without any special plugins for different graphic editors. More »

All the contacts and projects

Dmitry Vasiliev (just.dmitry)

More Online Helps

Win32 Programmer's Reference
Win32 Multimedia Programmer's Reference
OLE Programmer's Reference
Microsoft Windows Pen API Programmer's Reference
Microsoft Windows Sockets 2 Reference
Microsoft Windows Telephony API (TAPI) Programmer's Reference
Unix Manual Pages

greatis just4fun network