EC-Crypt is a fast, easy-to-use package for encrypting data files.
          Encrypting a file makes it impossible for someone else to read the file,
          unless you give them the key.  It may be used to encrypt any of your
          personal files, including files that you may send to other people as
          messages.  It does a medium-security encryption that will withstand any
          attack using a PC, even if your opponent is willing to devote years of
          computing time to the task.


            1.1. Easy to use
            1.2. Encrypting a file
            1.3. Decrypting a file


          3. CRYPTO TRICKS
            3.1. Key strength
            3.2. Extended keys
            3.3. Messages
            3.4. Rename me

          4. KEYS
            4.1. Key Do's and Don'ts
            4.2. Letters, digits and punctuation
            4.3. Key blocks
            4.4. Pronounceable keys
            4.5. Patterns
            4.6. Secretaries and clerks
            4.7. Key strength
            4.8. Summary: Picking a key

          Appendix A. DOS BASICS
            A.1. Starting DOS
            A.2. Sizing the DOS window
            A.3. Directories
            A.4. Current directory
            A.5. Working with directories
            A.6. Identifying files
            A.7. Long names
            A.8. File operations
            A.9. Batch files

          1.1. Easy to use

               The package is very simple to use.  You just type ECCRYPT on the
          command line, and you will be prompted for the key and the file name.
          Let's go through the steps.  The blue text is what you will see on your
          screen.  You type 


          and then press Enter.  EC-Crypt will ask you what you want to do.  

               Do you wish to
                 E - Encrypt the file.  Make it unreadable to protect it.
                 D - Decrypt the file.  Make it readable to use it.
                 Q - Quit.
               Type your choice (E, D, or Q):

          To Encrypt a file you type E.  To Decrypt a file you type D.

          1.2. Encrypting a file

               To encrypt a file you need to supply the key and the file name.  If
          your data is important, then it is important that you use a long and strong
          key.  There will be a whole chapter later about how to create a really
          strong key.  EC-Crypt will prompt you for the key.  

               The key may be any combination of up to 64 letters, digits,
               and punctuation.  The key is case-sensitive, so that
                    KEY   Key   key   kEY
                    KeY   KEy   keY   kEy
               are all considered different keys.  You may use letters, digits
               and punctuation marks, such as + $ " and :  All characters are taken
               as part of the key, including leading and trailing blanks.

               Enter the encryption key.

          You type your key at the prompt.  Be sure to check that you have typed it

               EC-Crypt has a valuable safety feature to help make certain that you
          do not use the wrong key later, when you try to decrypt the file.  This is
          the verification code.  

               Your verification code is   XXXX   Record your
               key and your verification code in a secure place.

               Press Enter when ready.

          The verification code will consist of 4 characters, which may be letters,
          digits or punctuation, for example R7M2 or 3Z#H.  Make sure that you write
          down your encryption key and verification code, and keep them in a secure
          place, for example, locked in a safe.  Do not let anyone see the key, or
          see where you put it.

               Next you need to tell EC-Crypt which file to encrypt.  You do not need
          to be concerned about the format of the file.  EC-Crypt can handle any file
          in any format created by any program.  You will be prompted for the file

               Enter the name of the file to be encrypted or decrypted,
               or type Q to quit.
               File name:

          Type the name of your file and press Enter.  For example, if you want to
          encrypt the file MergerPlan.pdf then you would type MergerPlan.pdf like

               Enter the name of the file to be encrypted or decrypted,
               or type Q to quit.
               File name: MergerPlan.pdf

          and then press Enter.

               You can encrypt or decrypt as many files as you wish each time you use
          EC-Crypt.  You will see 


               Do you wish to encrypt or decrypt more files (Y or N):

          If you have more files to encrypt or decrypt press Y for Yes, otherwise
          press N.

          1.3. Decrypting a file

               Decrypting a file is the opposite process from encrypting the file.
          You enter the same information as before.  

               Do you wish to
                 E - Encrypt the file.  Make it unreadable to protect it.
                 D - Decrypt the file.  Make it readable to use it.
                 Q - Quit.
               Type your choice (E, D, or Q):

          Type D to decrypt a file.

               You give the key next, but the process is slightly different.  

               The key may be any combination of up to 64 letters, digits,
               and punctuation.  The key is case-sensitive, so that
                    KEY   Key   key   kEY
                    KeY   KEy   keY   kEy
               are all considered different keys.  You may use letters, digits
               and punctuation marks, such as + $ " and :  All characters are taken
               as part of the key, including leading and trailing blanks.

               Enter the encryption key.

          After you type the key EC-Crypt will respond 

               The verification code is  XXXX
               Is this the correct code?
               Y = Yes, N = No, Q = Quit:

          Make sure this verification code matches the code you got when you
          encrypted the file, such as R7M2 or 3Z#H.  If the code does not match, then
          you typed the encryption key incorrectly.  Press N for No.  You will then
          get another chance to type the key correctly.

               Do not decrypt your file with the wrong key. If you do that, then you
          might lose the file permanently.  You must always type the encryption keys
          carefully and accurately, and check the verification code every time.

               Once you have checked that the verification code is correct, you give
          the file name just as above.  

               Enter the name of the file to be encrypted or decrypted,
               or type Q to quit.
               File name:

          Type in the file name and press Enter.  EC-Crypt will decrypt your file,
          and then prompt you for more files, just as before.


               EC-Crypt will be sent to you as a single zip file.  Download the file,
          unzip it, and copy the internal files into the folder (directory) where you
          want to use it.  Or, copy it first and then unzip it.  That's it.  EC-Crypt
          comes ready to use.  There is no further setup.

               If you plan to use EC-Crypt for several different types of documents,
          you can copy it into each folder so you have a local copy.  Then you don't
          need to specify a path when you start EC-Crypt.  You can have as many
          copies as you like.  They are all compatible.  They will not interfere with
          one another.  You can encrypt a file using one copy of EC-Crypt and decrypt
          it with another copy.

               Speaking of copies, be sure you put a copy of EC-Crypt on every one of
          your backup disks, flash drives, memory cards or other external storage
          devices.  If you use the Cloud for backup, and especially if you have
          automatic backup to the Cloud, do not put a copy of EC-Crypt or any file
          you intend to encrypt, or any file that you have already encrypted on the
          Cloud.  These files should be backed up only to storage devices that you
          keep in your personal possession.

          3. CRYPTO TRICKS

               You can make your files more secure if you know a few Crypto Tricks.
          You may need these tricks if your opponents have some expertise, or if they
          can devote time on mainframe computers to breaking into your files.  You
          will definitely want these tricks if your opponents could steal your
          computer or secretly copy your hard drive or backup devices.

          3.1. Key strength

               You need to pay some attention to how long and strong to make your
          key.  To get the full power of EC-Crypt, we recommend that you choose a key
          equivalent to 80 binary bits.  If your key consists of randomly chosen
          decimal digits, you should use a 25-digit key, such as

               40591 27360 14186 52694 37529

          If you are using a key of randomly chosen capital letters you will want a
          key 17 letters long, such as

               PRTNCI GRUYAV LHUOZ

          If your key consists of mixed upper and lower case letters, digits and
          punctuation, that is, you are using all of the characters on the keyboard,
          then 13 characters are enough, say

               K=dL4 2MaZ 5:1"

          The chapter on choosing keys will give you more ideas, but keep in mind
          that you are shooting for 80-bit key strength.

          3.2. Extended keys

               There will be a full chapter about keys later in this manual.  If your
          likely opponents are not crypto experts, you can just choose one long and
          strong key and use it for all of your files.  You can memorize the key, so
          you never write it down, and your opponent can never find it.  However, if
          you are facing a sophisticated opponent, you do not want to have many files
          all encrypted with the same key.  That gives your opponent more material to
          work with.

               One solution is to use key extensions.  Suppose your chosen key is
          KmR637-DgF452-WcN608 and you are encrypting a file named NewStoreLocations.
          You could add part or all of the file name to make the specific key for
          that file, for example KmR637-DgF452-WcN608-NSLoc.  The downside of this
          method is that you must not rename the file.  If you do need to rename it,
          you must decrypt it first, change the name, then encrypt it again using the
          new name and key, say KmR637-DgF452-WcN608-CookieRecipe.

          3.3. Messages

               If you are using EC-Crypt to encrypt messages that you are sending to
          and from another party, you need to give that other person the message key.
          This should be a different key from the ones that you use to encrypt files
          on your own computer.  You probably don't want to give that person a
          separate key for every message, yet it is less secure if you encrypt every
          message with the same key.

               One solution is to use message numbers, also called sequence numbers
          or message codes.  The first message you send could be called 0001, the
          second one 0002, and so forth.  These codes do not need to be secret.  You
          can put the sequence number right in the subject line of an email, and
          attach the message as a file.

               Suppose your key for communicating with your partner is LMSVT 29504
          QGVXO 68139.  When you send message 0006, you add the sequence number in
          some agreed format to the key.  So the key for message 0006 might be LMSVT
          29504 QGVXO 68139 :0006.

          3.4. Rename me

               A simple trick to use if you are hiding your files from people who
          might be in, or come into, your home or office is to rename all of the
          EC-Crypt files to other innocent-sounding names.  For example, you might
          rename ECCRYPT.EXE to CALENDAR.EXE or NOTEBOOK.EXE.  It is a good idea to
          use a name that people would expect to find on your computer.  For example,
          if you are known to be a coin collector, you might rename it to
          CoinList.exe, or CoinPal.exe or BestCoins.exe.

               Rename the other EC files accordingly.  If you want to be
          ultra-thorough, go into the EC-Crypt manual and change every place that it
          says crypt to something else.  That way, if your opponent searches your
          computer for references to encryption they won't find them in the EC files.

               They won't have a starting point for trying to break the encryption.

          4. KEYS

               Choosing the keys for encrypting your files is one of the most
          critical steps in using the EC-Crypt package.  If you choose a short or
          weak key, it may be easy to remember and easy to type each time you need
          it, but your data will not be secure.  It is a serious mistake to think
          that you can use a weak key simply because you are using such a strong
          encryption package.  A strong safe with a weak lock is not secure.

               If you choose a long strong key your data will be more secure, but it
          will be harder for you to remember it and to type it accurately each time
          it is needed.  This chapter will describe techniques for choosing keys that
          are both secure and easy to remember and to type accurately.

          4.1. Key Do's and Don'ts

               Many people try to take shortcuts in order to have keys that are easy
          for them to remember.  You need to assume that any opponent will also be
          aware of the same shortcuts.  Here are some simple rules that can help
          prevent a costly error.

               When you choose a key, do not base the key on your personal
          information.  Assume that your opponent knows all of your personal data.

          DO NOT base your key on 

               Your birthday
               Your telephone number
               Your Social Security number
               Your license plate number
               Your spouse's, child's, parent's, sibling's or even
                 your pet's name, birthday, phone number, etc.

          DO NOT base your key on commonplace phrases 

               Nursery rhymes
               Song titles or lyrics
               Folk sayings
               Names of famous people, groups, places or events
               Names of books, plays or TV shows
               Punchlines from jokes
               Well-known dates
               Tongue twisters
               Words or phrases in other languages

          DO NOT use data widely known within your specialized field 

               Digits of pi or e
               Names of bones, nerves, or organs
               Names of stars, minerals, geological features, bacteria,
                 ancient cultures, alloys, proteins, theorems, etc.
               Names of people, schools, companies, places, etc.
               The speed of light, Avogadro's number, the Golden Ratio, etc.

          DO NOT choose sequences of consecutive letters from the alphabet or from
          the keyboard, whether forwards, backwards or diagonally.

          DO NOT use the keys that appear in this manual.  Always assume that your
          opponent has read it, too.

          DO use a long key.

          DO try to make your key as random as possible.

          DO read this entire chapter on picking keys.

          DO evaluate the strength of your key according to the principles in the
          following sections.

          DO make your Master Key extra long and strong.

          4.2. Letters, digits and punctuation

               If there are several people who need access to the data, and who are
          trusted with the keys, then the problem of recording or memorizing the keys
          becomes multiplied.  Some people have the capacity to memorize long strings
          of random-looking letters and/or digits, but most people cannot do this.
          The safest course is to write down your key, and keep it in a secure place,
          such as a locked safe.  Other techniques will be discussed in a later
          section.  It is advisable to have several copies, in case one copy gets
          lost, stolen or destroyed.

               The strength of an encryption key is measured in bits, the binary
          digits that are used by your computer's hardware.  Here is a rough guide to
          how many bits you get from each character in an encryption key when the
          characters are chosen randomly.  

               Table 1.  Strength of each character in a key.

               Decimal digits = 3.3 bits
               Single case letters = 4.7 bits
               Mixed case letters = 5.7 bits
               Mixed letters and digits = 5.9 bits
               Mixed letters, digits and punctuation = 6.3 bits

          Based on this chart, here is the strength of some sample 10-character keys 

               Table 2.  Strength of 10-character blocks.

               5835701483 = 33 bits   Decimal digits
               CIWMRPTNZX = 47 bits   Upper case letters
               tyuhbivxks = 47 bits   Lower case letters
               DmbHaqREkV = 57 bits   Mixed case letters
               ku8Je94Lg7 = 59 bits   Mixed letters and digits
               g"p5WZc4%F = 63 bits   Mixed letters, digits, punctuation

               As you can see, the strength of the key increases when you choose
          randomly from a larger set of characters.  However, the difficulty of
          memorizing the keys and typing them accurately becomes much greater as the
          keys get more random.

               Note that all of the keys illustrated above are too short to be
          considered secure.

          4.3. Key blocks

               There are several methods for producing keys that are secure, yet
          easier for people to manage.  The first technique is to break your keys
          into blocks.  It has been a common practice for many years to break coded
          messages into blocks of 5 characters each so that they can be transcribed
          more accurately.  The same idea works for keys, too.  Notice how the key 


          becomes much easier to read when it is broken into groups of 5 letters 


               For longer keys it may be advisable to use additional punctuation to
          organize the blocks into groups of blocks.  For example, 

               48591-04528-16392, 35207-31654-74925, 09482-71653-42570


               The second technique is to use groups that have the same structure.
          Here are some examples, and the strength of each key block 

               91486 61872 94373   16 bits per block   5 digits
               T3708 D6204 F5193   18 bits per block   1 letter, 4 digits
               GS437 BR092 LX528   19 bits per block   2 letters, 3 digits
               UHM15 XTN63 MYA74   21 bits per block   3 letters, 2 digits
               QRILC PJRMS OVDZK   23 bits per block   5 letters

          The strength remains the same when the letters are placed in different
          positions.  For example, all of the following keys have the same strength,
          namely 2 letters and 3 digits 

               GS437 BR092 LX528   Letters at the start of each block
               943KP 471GQ 205YL   Letters at the end of each block
               V107J X219C F738L   Letters at both ends of each block
               6WF52 9TU48 7JN13   Letters in the middle of each block

               One advantage of using key blocks that always have the same structure
          is that there is no confusion between letters and digits.  Some letters and
          digits that may get confused are 

               Letters   B G I l O S T Z
               Digits    8 6 1 1 0 5 7 2

          Its position in the block tells you whether the character is a letter or a
          digit, so there is no need to avoid these characters when you use blocks
          with a fixed structure.

               Another variation on this idea is to make each key block uniform, but
          to vary the types of blocks randomly.  Here are two 30-character keys with
          uniform blocks.  Each block consists of all digits, or all uppercase
          letters, or all lowercase letters.  

               KNUHW 50258 fewrz 39274 gyakf obqnk

               doztc 81463 69917 AGNDL rdefo PUIZH


          4.4. Pronounceable keys

               Another technique that can be used to produce keys which are secure,
          yet easy to remember, is to make the keys pronounceable.  That is, you
          would use pronounceable combinations of vowels and consonants to form
          syllables, and combine these syllables to form artificial words.  This
          method may be valuable in situations where it is unsafe to write down the
          keys, and they must be memorized.  Here are some examples.  

               shambu dilp prelec oltu domex sarbuti shum obior

               Yotz doruc flean jadmek pra kerazi, Lagatu limbrazon.

               You can burn the key into your memory by starting with just a few
          artificial words, say DOZEK ULM HAPLICO, and repeat these to yourself for a
          day or two.  Then add another few words, say DOZEK ULM HAPLICO GRUX ANTIAM,
          and repeat those in your head for a few more days.  You can add some more
          words the following day.  

               dozek ulm haplico grux antiam ludovesk gur amesqi

               You can complete the process by adding capitalization and punctuation,

               Dozek ulm Haplico "Grux Antiam" ludo-vesk gur a'mesqi.

          Using mixed-case letters and punctuation increases the strength of your

               You can imagine the key to be a saying in some private language, and
          make up a translation, in order to fix it more firmly in your mind.  For

               Wise king Haplico "Lion of Antioch" out-witted a sorcerer.

               In a pronounceable key each letter has a strength of about 3.3 bits if
          the words are fairly uniform in length, and about 3.5 bits if the words are
          more variable in length.  For example, the first key below is fairly
          uniform in length, while the second is more variable.  

               panek dilbap greho drung fasdop ulben bukty crivan

               lobykar elb dixiat glem urbiqeo dhorsh uz vilagump


          4.5. Patterns

               When choosing a key, avoid creating any patterns, such as repeated
          letters or syllables.  Patterns weaken the keys by making them easier to
          guess.  Here are some examples of keys with patterns.  

               BBXXTT KKUUVV WWYYCC      The letters are all in pairs.
               aaa3gg5yyyy9ccc7uu2       There are runs of equal letters.
               10704 20906 50803         The second and fourth digit in
                                         each group is zero.
               51615 38183 29092         Each group has an ABCBA pattern.
               zampana reveske flogoto   The vowels in each group are all
                                         the same.
               tuntam memescu saksoli    The first and second syllable
                                         start with the same letter.
               debendik devogi delakt    Every group starts with de.
               ABC ghi LMN def XYZ       Each group has 3 consecutive
                                         letters of the alphabet.
               500XD 711TJ 822GN         The second and third digits in
                                         each group are the same.
               31734 23839 30376         Every group has two 3's.
               dobaku levoti wafigo      Consonants and vowels alternate.
               vgy7 2wdc zse4 7ujm       Has diagonal runs on the keyboard.
               KAZ VEK CIF ZOP HUQ       The vowels run in order AEIOU.

               Once you have chosen a key, inspect it for patterns, and change it to
          remove them.  If your key is a long string of letters or digits, look to
          see if there are any letters or digits that are used too often, or that are
          missing.  You may want to make some changes.  However, don't overdo it.  If
          you use every letter or every digit exactly the same number of times, or if
          all the letters and digits in each block of your keys are always different,
          those are also patterns which weaken the key.

          4.6. Secretaries and clerks

               Sometimes lower-echelon employees will not safeguard file keys as
          zealously as other workers.  It is common for these employees to write down
          keys in places that are easily accessible, such as on the computer itself,
          on their desk pads or wall calendars, or on slips of paper on a bulletin
          board.  Anybody could see the keys and write them down.  It is absurd for
          the company president to keep the Master Key in a locked box inside a
          walk-in vault, and for the secretary's assistant to write the Master Key on
          a gummed label on the wall next to the computer.

               The employee might assume that nobody will ever guess that those
          cryptic letters and digits are actually the Master Key that unlocks all of
          the company's secret files.  The employee might assume incorrectly.  If
          these employees must be trusted with the keys then it is essential that
          they be educated to avoid such security breaches.

               Keys should never be written or pasted on the computer itself, the
          computer desk, a desk pad or calendar, the cover of a notebook or steno
          pad, the bottom of a stapler, telephone or flowerpot, the back of a
          clipboard, letter tray or desk organizer, or any similar place.  Intruders
          know to look in such places.  Don't make their job easy.

          4.7. Key strength

               The following table is a guide to how long a key must be in order to
          achieve various levels of security.  For example, if you want a key
          strength of 200 bits, and you use a decimal key, then you need 60 digits.
          With the speed of current computers 100 bits is the lowest level of
          security that can be considered safe.

               The table assumes that the letters or digits of the key are chosen
          completely randomly.  If the letters or digits follow some pattern then
          your key needs to be longer.  For example, a key such as 

               TC174 JF296 BH583 KD629

          would be measured as 8 single-case letters and 12 digits, for a total
          strength of 77 bits.  Because of the LLDDD pattern it would not be
          considered to be 20 mixed letters and digits, which would have a strength
          of 118 bits.  

          Table 3.  For each type of key, this table shows how long to make
                    the key in order to achieve the desired strength.

                                   Desired key strength measured in bits
          Type of key             100   125   150   200   250   300   400
          Decimal digits           30    38    45    60    75    90   120
          Single-case letters      21    27    32    43    53    64    85
          Mixed-case letters       18    22    26    35    44    53    70
          S-C letters + digits     19    24    29    39    48    58    77
          M-C letters + digits     17    21    25    34    42    50    67
          Letters, digits, punc    16    20    24    32    40    47    63
          Uniform blocks           22    27    33    44    55    66    88
          Pronounceable, uniform   30    38    45    60    75    90   120
          Pronounceable, variable  29    36    43    57    71    86   114

          For example, if you wanted a decimal key you would read across the top row
          of this table.  If you wanted the decimal key to have a strength of 125
          bits, you would look at the second column in the top row to find that you
          would need 38 decimal digits.  If you wanted a key of mixed-case letters
          and digits with a strength of 250 bits, you would need 42 letters and

               Note that the longest input line you can enter is 126 characters.
          (This is a limitation of DOS, not a limit set by EC-Crypt.)  So if you
          wanted 400 bits of strength, and you chose to have a decimal key which
          requires 120 digits, then you would have only 6 characters left to separate
          the blocks.  Your blocks would need to average over 17 characters each.  (A
          pattern of 17, 17, 17, 17, 17, 17, 18 would fit.)

          4.8. Summary: Picking a key

          The best way to pick a key is to follow these steps.

          (1) Decide how strong you want your key to be, say 200 bits.
          (2) Choose the type of key, say blocks of letters and digits.
          (3) Use the tables above to determine the key length.
          (4) Randomly choose a key of the required length.
          (5) Inspect the key for patterns.
          (6) Adjust the key to remove or reduce the patterns.
          (7) If you will need the key again, write down the key and keep
                  a copy in a secure place.
          (8) Type the key when EC-Crypt asks for it.

          Appendix A. DOS BASICS

               EC-Crypt runs under DOS, not under Windows.  DOS was the primary
          operating system for personal computers from about 1975 to 1995.  Older
          versions of Windows, prior to the introduction of Windows 95, ran as tasks
          under DOS.  Since 1995 the situation has reversed, and DOS now runs as a
          task under Windows.  Every computer user before 1995 knew DOS well.
          However, newer computer users may not be familiar with DOS, so that a
          little basic orientation may be helpful.

          A.1. Starting DOS

               On newer computers it may be difficult even to find DOS in order to
          use it.  There are two methods for running DOS.  The first method is to
          click on a DOS icon from your desktop, or from a taskbar at the top or
          bottom edge of the desktop.  The icon may say DOS, or MSDOS, or possibly
          CMD or COMMAND.  Clicking any one of these icons will start DOS.  If there
          is a DOS icon on your desktop or in a taskbar, you can skip the rest of
          this section.

               If there is no DOS icon on your desktop or taskbar you may find one
          elsewhere.  Start by clicking on "Start" in the corner of the screen.  This
          will bring up a menu listing various programs and options.  If there is a
          DOS icon there, you can use it directly, or you could drag it onto the
          desktop for future use.  If it is not there, click on "Programs" or "All
          Programs."  This will bring up a long list of various programs that are on
          your computer.  If one of these is DOS, you can click it, or you can drag
          it to the desktop.

               If you still don't see a DOS or CMD icon, put your mouse on each of
          the icons that you see.  Don't click, just let the mouse cursor rest on the
          icon.  This will often bring up another list of programs, and DOS may be
          among them.

               If DOS still is not there, don't give up.  You just need to search
          deeper.  In the list of All Programs there will be some folders with names
          such as "Applications" or "System Utilities."  Click to open each of these
          folders.  In those folders you may find DOS or CMD.  Or, you may find more
          folders.  Again, rest the mouse on the names of programs, and click on
          folders to find even more well-hidden programs and folders.

               Once you find the DOS icon, drag it to the desktop.  Put the mouse
          cursor on the DOS icon and hold down the left button.  Move the mouse to
          drag the cursor onto the desktop, and then release it to drop the icon on
          the desktop.  Click the desktop to close all of the other windows.  Then
          drag the DOS icon to wherever you want it on the desktop.

               If all of this fails, it is time to try the second method.  Go back to
          the desktop, and click on "Start" again.  In the list of options click on
          "Run" or "Run Program."  This will open a small window with a box where you
          can type the name of a program that you wish to run.  Type CMD in this box,
          and then press Enter.  This will open a DOS window.

          A.2. Sizing the DOS window

               The DOS window will often be a small window in the middle of the
          screen, probably off-center.  It is easier to work with DOS in full-screen
          mode, with no distracting windows or borders.  To do this, right click on
          the top border of the DOS window, and select "Properties" from the pop-up
          window that appears.  Use the various options to select full-screen mode.
          This may take several tries before it works, so don't get frustrated if the
          next time you use DOS you get the same small window, and need to resize it

               When you do get the full screen mode, the screen is likely to be set
          to 50-line mode.  This makes the characters small and crudely formed.  You
          may be more comfortable using 25-line mode.  To switch, you can type the

               mode con lines=25

          This will double the size of the characters and make them easier to read.

          A.3. Directories

               In DOS your computer's hard disk is organized into directories.  All
          of the files on your computer are in directories.  These correspond to the
          folders in Windows.  Directories and folders are the same thing.  A
          directory or a folder can contain files and more directories or folders, so
          that the folders or directories are nested one inside the other in a

               The top of the hierarchy is called the "root directory."  Typically
          the root directory does not contain any files.  Rather, it contains all of
          the principal directories on the computer, such as

               \Program Files
               \Documents and Settings

          and so forth.  The backslash \ in front of these directory names shows that
          they are directories within the root directory.

               A directory within another directory is sometimes called a
          subdirectory.  In the example above the directory Windows would be a
          subdirectory of the root directory.

          A.4. Current directory

               Files are identified in DOS by using a path, a filename and a
          filetype.  For example,


          Here the path is direc1\direc2, the filename is file1 and the filetype is
          doc.  The path consists of the sequence of nested directories which contain
          the desired file.

               If the path starts with a \ backslash, then the sequence of
          directories start from the root directory.  If the backslash is omitted,
          then the path starts from the current directory.  For example, if the
          current directory is Windows, then the file identifier
          direc1\direc2\file1.doc would refer to the file

               By setting the current directory you can shorten the names of programs
          and files that you must type.  For example, if you want to use the program


          to process the data files


          you could type

              \direc1\direc2\prog1 \direc1\direc2\file1.dat \direc1\direc2\file2.dat

          If you changed the current directory to \direc1\direc2 then this could be
          shortened to

              prog1 file1.dat file2.dat

              The command to change the current directory is cd.  To change the
          current directory to \direc1\direc2 you would type

               cd \direc1\direc2\

          If you later wanted to change the current directory to
          \direc1\direc2\direc3 it is sufficient to type

               cd direc3

          since you were already in the directory \direc1\direc2.

          A.5. Working with directories

               You can make your own directories by using the Make Directory command.
          For example, if the current directory is \direc1\direc2 and you wanted to
          make a subdirectory called direc3, then you could type

               md direc3

          Starting from the root directory, the new directory would be

               To remove a directory, you can use the Remove Directory command.  For
          example, to remove the directory \direc1\direc2\direc3 you would type

               rd \direc1\direc2\direc3

          As a safety precaution, you cannot remove a directory until you have
          deleted all of the files in the directory, and removed all of its
          subdirectories.  This prevents you from accidentally deleting files that
          you meant to keep.

               To list the contents of a directory, you can use the Directory
          command.  The basic format is

               dir mydirec /options

          Here mydirec is the directory you want to list.  There are many possible
          options.  Here are a few of the most useful:

               /s    List the contents of all subdirectories
               /on   Sort the files by name
               /os   Sort the files, smallest to largest
               /o-s  Sort the files, largest to smallest
               /od   Sort the files, oldest to newest
               /o-d  Sort the files, newest to oldest
               /p    Pause after every 20 lines

          You can use several options in the same command.  For example,

               dir \direc1 /s /od /p

          would list the files in \direc1 and all of its subdirectories sorted from
          oldest to newest, and pausing after every 20 lines.

               You can also list specific files, files that have a given filename or
          filetype, or files whose filenames and filetypes begin with specific
          letters.  Here are some examples

               dir tax.ref   Lists the file tax.ref.
               dir tax.*     Lists all files with the name tax.
               dir *.doc     Lists all files of type doc.
               dir st*.c*    Lists all files whose filename starts with st
                             and whose filetype begins with c, such as
                             startup.cfg, study.com or state.core.

          The * asterisks in these commands are called wildcards because they can be
          replaced by any set of letters.  These commands can tell you whether these
          files exist, their sizes, and the date they were last updated.

          A.6. Identifying files

               All of the data in your computer resides in files.  Files contain the
          operating system, all of the application programs, and all of the data that
          they use and create.  Files are identified to DOS by four fields, namely
          the drive, path, filename and extension.

               drive      is the device where your file is stored, usually
                          C for your hard drive, A or B for a floppy drive,
                          D or E for a CDROM drive.

               path       is the directory on your drive where the file is

               filename   is the name that you gave your file.  The name
                          usually indicates the contents or purpose of the

               extension  is a suffix that indicates the kind of file, such
                          as TXT for a text file, JPEG for a picture file,
                          EXE for an executable file, etc.

          A full file identifier might look like this,


               In this example, c: identifies that your file is on the C drive, which
          is your hard drive.  \mycompany\mydepartment\2005\ is the path to your
          data.  It shows that the data file is located in the 2005 folder, which is
          inside the mydepartment folder, in the mycompany folder.  So the path
          consists of nested folders, or a list of directories.  sales.wp is the file
          with the data.  The filename is sales, and the extension is wp, which
          indicates that it is a WordPerfect document.

               In a file identifier all of the fields except the filename are

               drive      can be omitted if the file is on the current
                          drive, that is, the drive where you are now

               path       can be omitted if the file is on the current
                          directory of the drive.

               extension  can be omitted if the file does not have an
                          extension on its name.  For example, if the file
                          is just named oldstuff then no extension is

          Here are some examples of valid file identifiers:

                    identifies the file budget in the current directory
                    of the A drive.

                    identifies the file commissions in the jones directory
                    on the current drive.

                    identifies the file requests.txt in the late
                    subdirectory of the current directory.

          A.7. Long names

               Some Windows files and directories have long names, or names
          containing blanks or dots, such as

               Documents and Settings
               My Music

          Microsoft has made the naming of files and directories incompatible between
          Windows and DOS.  DOS limits directory names to 8 characters, and does not
          allow blanks in names.

               To refer to these directories, you need to shorten the names down to 8
          characters.  The short name is formed by taking the first 6 non-blank
          characters of the name plus the combination ~1.  When the name of a
          directory contains a . dot character, each of the parts of the name is
          treated separately.  For example, for the directories above,

               Documents and Settings   would be called   Docume~1
               My Music                 would be called   MyMusi~1
               Microsoft.Net            would be called   Micros~1.Net
               SharedReg12.dll          would be called   Shared~1.dll

          Thus a full path and file name such as


          in DOS would be called


               It is a good idea to give all of your own files and directories names
          that are compatible with DOS.  The names should be no more than 8
          characters long and should not contain blanks.

          A.8. File operations

               Besides the encryption and decryption operations that you perform
          using EC-Crypt, it can be useful to know several other common file

               There is no DOS operation to create a file.  Files are created by
          application programs such as word processors, picture editors,
          spreadsheets, etc.  Once created, files can be copied, renamed and deleted.

               It is important to remember that encrypted files should not be
          renamed, and files should not be copied into or out of a group of encrypted
          files.  It is safest to decrypt files before renaming or copying.

               To copy a file to a new location, the command is

               copy oldfile newfile

          The old file and new file identifiers can be fully qualified, that is, they
          may have drive, path, filename and filetype.  So the copy command can be
          used to copy files to other directories or to other drives.

               Wildcards can be used in the copy command to copy groups of files.
          For example, the command

               copy \oldpath\*.doc \newpath\*.*

          would copy all files of type doc from the \oldpath directory to the
          \newpath directory.

               The rename command works similarly to the copy command.  The form is

               ren oldfile newname

          Here oldfile can be fully qualified, with drive, path, filename and
          filetype.  However, newname can have only a new filename and filetype.
          There cannot be a new drive or new path because the file does not change
          its location, only its name and/or type.  For example,

               ren target\x3*.jpg x4*.*

          would rename all of the jpg files in the target directory that start with
          x3 to start with x4.

               The command to delete files takes the form

               del file

          Here, file can be a fully-qualified file identifier, with drive, path,
          filename and filetype.  It can also have wildcards so that you can delete
          several files with a single command.  For example,

               del a:old*.*

          would delete all files in the current directory of the a drive whose
          filenames start with old.

               Note that deleting a file does not erase it.  The file still exists on
          the disk, where it can be read by various utility programs that are
          available for that purpose.  The file will remain there until some other
          file eventually gets written on top of it.

          A.9. Batch files

               Batch files are a useful way to reduce the number and complexity of
          the DOS commands that you must type.  Each batch file can contain any
          number of DOS commands.  You execute the entire sequence of DOS commands
          just by typing the name of the batch file.

               Here is a simple example.  Suppose that you frequently use the program
          EC-Crypt.  If the current directory is \plans\tower but EC-Crypt is in the
          directory \programs\download then to use EC-Crypt you would type


          To make this easier, you could create a batch file named ECCRYPT.bat on the
          current directory.  This file would contain the single line


          Now when you wanted to execute EC-Crypt all you would need to type is


               You could place a copy of the batch file ECCRYPT.bat in every
          directory where you usually work.  Then you could run EC-Crypt from
          anywhere just by typing ECCRYPT.  You would not need to have multiple
          copies of EC-Crypt.

               There are many other DOS commands and options.  This is just a small
          sample of useful DOS commands.

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© Copyright 2024 Frank Rubin
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