What is a digital signature?

what is a digital signature? A digital signature is basically a way to ensure that an electronic document, like an email message, or a spreadsheet or a text file, is authentic. Authentic means that you know who created the document, and you know that it has not been altered in any way since that person created it. Digital signatures rely on

certain types of encryption to ensure that authentication. Encryption is the process of taking all the data that one computer is sending to another computer and encoding it into a form that only the receiving computer will be able to decode. Authentication is the process of verifying that unaltered information is coming from a trusted source. These two processes were cand in hand for digital signatures. There are several ways to

authenticate a person or information on a computer. The most common way is to use some kind of password scheme. The use of a user name and password provide the most common form of authentication. You enter your name and password when prompted by the computer. It checks the pair against the secure file to confirm. If either the name or the password don't match, then you're not allowed further access to the document. Many text editors, like Microsoft Word

offer this feature. You simply encode the document before you send it, put the password on it, and then the recipient who you tell the password to, the only one who can read that document. The second idea is a checksum. It's probably one of the oldest methods of ensuring that data is correct, and checksums also provide a form of authentication, since an invalid checksums suggests that the data has been compromised in some fashion while it was being sent. A

checksum is determined in one of two ways. Let's say that the checksum of a packet is one bite long, which means it can have a maximum value of two fifty five. If the sum of all the bites in the packet is two fifty five or less, then the checksum contains that exact value. However, if the sum of the other bites is more than two D fifty five, then the checksum is the remainder of the total value

after it's been divided by two D fifty six. Another technique called a CRC or cyclic redundancy check, is similar in concept to checksums. Neither checksums or CRCs really provide any protection of the data. They just tell you that it hasn't been tampered with as it made its way

to your computer. Then there's private key encryption. Private key means that each computer as a secret key or secret code that it can use to encrypt a packet of information before it's sent over the network to the other computer. Private key requires that you know which computers will talk to each other and install the key on each one

ahead of time. Private key encryption is essentially the same as a secret code that the two computers must each know in order to decode the information when it arrives. The code would provide the key to decoding the message. Your friend gets the message and then decodes it. Anyone else who sees the message will see only nonsense because they don't have the key. Then there's public key encryption. Public key encryption uses a combination of a private key

and a public key. The private key is known only to your computer, while the public key is given by your computer to any computer that wants to communicate with it. To decode an encrypted message, a computer must use the public key provided by the originating computer and its own private key, and then there are digital certificates. To implement public key encryption on a large scale, such as a secure web server might need, requires a different approach. This

is where digital certificates come in. A digital certificate is essentially a bit of information that says the web server is trusted by an independent source known as a certificate authority. The certificate authority acts as a middleman that both computers trust. It confirms that each computer is in fact who they say they are, and then provides the public keys of each computer to the other. The Digital Signature Standard is based on a type of public key encryption that uses

the digital signature out gorhythm. The Digital Signature Standard is the format for digital signals that's been endorsed by the US government. For more on this and thousands of other topics, visit how Stuff Works dot com, and don't forget to check out the brain Stuff blog on the house stuff works dot com home page. You can also follow brain stuff on Facebook or Twitter at brain stuff hs W. Audible dot com is the leading provider of downloadable digital

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