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The process of making
data
unreadable by other humans and/or
computers for the purpose of preventing others from gaining
access to its
contents.
Encrypted data is generated using an encryption
program
such as PGP,
encryption machine, or a simple encryption
key and
appears as
garbage
until it is decrypted. In order to read or use the data, it must be
decrypted and only those who have the correct
password
and/or
decryption key are able to make the data readable again.
A very basic encryption technique known as simple
substitution or a substitution cipher shifts the letters
of the alphabet over a few characters. For example, as shown below
the alphabet has been shifted over four characters.
Encrypt key:
a=e, b=f, c=g, d=h, e=i, f=j, g=k, h=l, i=m, j=n, k=o, l=p, m=q,
n=r, o=s, p=t, q=u, r=v, s=w, t=x, u=y, v=z, w=a, x=b, y=c and z=d.
Decrypt key:
a=w, b=x, c=y, d=z, e=a, f=b, g=c, h=d, i=e, j=f, k=g, l=h, m=i,
n=j, o=k, p=l, q=m, r=n, s=o, t=p, u=q, v=r, w=s, x=t, y=u and z=v
Using this technique a user could encrypt the message: "computer
hope free help for everyone" to: "gsqtyxiv lsti jvii lipt jsv
izivcsri". Below is an example of how this could be done using
Perl.
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$alpha = "abcdefghijklmnopqrstuvwxyz";
$message = "computer hope free help for everyone";
@alpha = split(//, $alpha);
$i=1;
foreach $alpha (@alpha) {
if ($i >= 23) {
$i = -3;
}
$key{$alpha} = $alpha[$i+3];
$i++;
}
@message = split(//,$message);
foreach $message (@message) {
if ($message =~/[a-z]/i) {
$new .= "$key{$message}";
}
else {
$new .= "$message";
}
}
print "Old: $message\nEncrypted: $new\n";
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Also see: AES,
Asymmetric
Encryption, Cleartext, Cryptography, Decryption,
DES, Key, MDC, Node
encryption, PGP, Security
definitions
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