From: catalyst-remailer@netcom.com
Newsgroups: eff.mail.cypherpunks
Subject: Magic Money 1.1/AutoClient
Date: 31 May 1994 02:59:26 -0400

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Magic Money V1.1 with AutoClient and MultiServer Capability
Uploaded to csn.org, should be available soon. Read README.MPJ in /mpj
This is the automatic client I described a couple of weeks ago.

This is a new version of Magic Money. It is compatible with V1.0 in both
directions. The major improvements are:

* Automatic Client allows software-automated services to accept and
  pay out Magic Money.

* Coin files contain the keyid of the server that created the coins.
  This allows the Automatic Client to accept money from multiple servers.

* New fifo.c fixes a memory-freeing bug in fifo_destroy. This fix was
  previously posted on csn.org as pgptlupd.zip

The keyid is appended to the end of the coin file with a new packet
type number preceding it. These coin files will be accepted by the V1.0
client. V1.0 coin files will also be accepted by the V1.1 clients.
See the README10.DOC file for more general instructions about how to
use Magic Money. This file concentrates on the changes.

The Automatic Client performs the same functions as the manual client,
except that it has no user interface. It is designed to be controlled by
software (PERL scripts or C programs). The program is controlled by
command-line arguments and information piped into stdin. All output is
written to files or sent to stdout. Compiling AC.C with MM.C and the
appropriate PGPTools files produces the Automatic Client. If you are using
a PC, it is worthwhile to get the 8086.ASM file from PGP2.3a and use it.
Define MSDOS, SMALL_MEM, DYN_ALLOC, and UPTON for the MS/DOS version with
8086.ASM. These defines work for both the normal and automatic clients.

Automatic Client Commands

The automatic client accepts one option, and zero, one, or two filenames.
If run with no options or filenames, it will print a help screen.

ac -[option] [inputfile] [outputfile]

- -k display bank's keyid and client's keyid
This prints the keyid of the bank on the first line, and the keyid of
the client on the second line, as 8-byte hex strings.

- -k [inputfile] display keyid of bank which made this coins.dat file,
   or the keyid needed to decrypt an ascii-armored pgp message.
If the file is a coins.dat-type file produced by a client, this will
produce the keyid of the bank that created it. If it is a PGP message,
such as a reply from a server, it will produce the keyid the message
is encrypted with. In either case, it returns an 8-byte hex string.
If the file is from a 1.0 client, there is no keyid so you will get
a NO_DATA error. There is a 1/256 chance that the byte at offset 9
from the end of file will match the identifier byte. In this case, you
may get a no-good server id. If you get a server id but do not recognize
it, assume this has happened.

- -d list coin denominations
Prints the available denominations of coins from the elist file, one
denomination per line. These are all the possible denominations, and their
presence here does not mean you have any coins of that denomination.

- -i [outputfile] initialize client (key length, key name from stdin)
This initializes the client, producing the initialization message
(which must be sent to the server) in the specified file. The bank.asc
file must be present before running this. It creates a key to communicate
with the server. The key length in bits, and the name for the key, are
read from stdin. They should be on separate lines.

- -l list all coins in allcoins.dat
Lists all available coins as a stream of numbers, one coin per line.

- -l [inputfile] print total value of a coins.dat (client output) file.
   Checks signatures and rejects if signature bad
Prints one number, the total value of the coins.dat file specified. If
any signatures are bad, or coins have unknown exponents, the program
terminates with a BADSIG or BADEXP error.

- -p [inputfile,outputfile] process a coins.dat file for exchange with
   the server. Reads from stdin a list of coin denominations to create,
   terminated by 0. Writes to stdout a 128-bit transaction identifier.
Before running this, you must have used the -l above and decided what
denominations to create. Then run this to process the coins and prepare
a message for the server. Feed the denominations you want into stdin, one
number per line, terminated by a zero. There is no checking here. If you
specify less value than you are turning in, you will lose value. If you
specify more, the server will throw out the transaction and you will lose
all the coins you are depositing. This function writes out one value to
stdout: a 128-bit hex identifier. This is an xor of the coinids of all of
the new protocoins created. This allows your script to identify this
transaction when it comes back from the server.

- -r [outputfile] Reinitialize (generate init packet)
This generates a new client initialization packet. If your system is
inactive for a while, do this, send it in, and run -s on it. This will
check for a coin expiration and update your elist if necessary.

- -s [inputfile] Process a response from the server. Outputs the 128-bit
   transaction identifier, followed by total value, followed by any
   message from the server.
This takes a reply from the server (ascii-armored) and processes it,
adding new coins to your allcoins.dat file and removing the corresponding
protocoins. The output is: on the first line, the same 128-bit identifier
generated by -p when this transaction was prepared. On the second line,
the total value added to your coin file (same as the value of the coins
you created in the -p). Following that, any message from the server, if
there is one. If -s is run on a response to a -i or -r initialization, it
will return 00..00 for the identifier and 0 for the value, because no
coins were processed.
		     
- -w [outputfile] Withdraws coins for payment. Accepts a list of coin
   values from stdin, terminated by a zero.
Extracts coins from your allcoins.dat file and writes them to the output
file. Send to stdin a list of values to create, followed by a zero to
terminate. The output file can then be processed by another client.

- -x Returns the total value of any old coins (in danger of expiration)
Checks for old coins that are in danger of expiring. Outputs the total
value of all old coins, or zero if there aren't any.

- -x [outputfile] Exchanges old coins. Accepts a list of denominations
   and generates an identifier like -p
This is like -p for old coins. Run -x above first, decide what denomin-
ations you want to create, and run this. Feed in the denominations, term-
inated by a zero, and send the output file to the server to exchange your
old coins for new ones. If you have expired coins (you didn't exchange
them in time) this will throw them out.

Error codes (from MM.H) These are returned by exit(code) when the
program ends. A 0 is good, anything else is bad. The only errors
that are not included here are out-of-memory and missing rand.dat
file. These will still print English messages, however, if the system
is correctly set up, they should not happen.

#define MMAC_OK 0                 /* Normal exit */
#define MMACERROR_BADCOMMAND 1    /* Bad command */
#define MMACERROR_NOFILE 2        /* File not found or inaccessible */
#define MMACERROR_NODATA 3        /* Data such as a key not found */
#define MMACERROR_BADSIG 4        /* Coin/file has bad signature */
#define MMACERROR_BADEXP 5        /* Coin has unknown exponent */
#define MMACERROR_NOCOIN 6        /* Tried to use nonexistent coin */
#define MMACERROR_NOPROTO 7       /* No protocoin in file */

Using the Automatic Client

Ok, that's great, but how do I use it? For an automatic service, you want 
to receive coins, process them, get the response back from the server, and 
then perform some service. You may optionally want to send some coins back 
to the person. So first, when a message comes in, you have to decrypt it 
or dearmor it or uudecode it, or whatever is necessary to get a binary 
coins.dat file. Then run -l [file] to check its value. If you get a value
and not an error, figure out what denominations you want. -d will list all
possible denominations. Now run -p [file] [output file] and send it your
list of denominations. Record the transaction id output from the client,
along with whatever information you need to keep about the service the
customer wants. Mail the output file off to the server, and go on to the
next problem.

When the message comes back from the server (-k [file] and compare with -k
to verify it is encrypted for your client) run -s [file] on it to deposit
the coins in your allcoins.dat file. The output from the client gives you
the transaction id, value, and any message. Use the transaction id to
look up the information you recorded earlier, and deliver the service to
the customer. The value can be verified if you want, and the message
should probably be saved in a file for later reading. You can check each
new message against the last one and only save it if it has changed.

Occasionally run a -x to see if you have any old coins. If so, figure out
what denominations you want to trade them for, and run -x [file] to
exchange them. You can probably do this part by hand, since coin
expirations are pretty rare.

To pay out money, do a -l to find the denominations to extract, then do
a -w to withdraw them into a coins.dat file.

Handling Multiple Servers

You can run a service that accepts coins from multiple servers. To do
this, you have to keep a separate client directory for each server. When
a coin file comes in, run -k [file] to determine which server it is for.
Using the server id as the directory name would make life much simpler.
Then CD into that directory and process the coins from there. If you get
coins from a 1.0 client (which has no server id), you will have to go
into each directory in turn and try a -l [file] on the coins. You will
get an error return on each one until you find the right directory. If 
messages are coming back from multiple servers, using -k [file] on the 
incoming message will tell you which client's key it is encrypted with. 
Running -k will tell you the key of that client (on the second line). 
- From this, you can determine which client should process that server's 
reply. This is probably easier than using the from line in the email.

Ideas for Automated Magic Money Applications

Currency Exchange - Accept one currency and return another, skimming off
a profit. Find the correct exchange rates where the same amount of each
currency is coming in and going out.

Pay-For-Use System - Accept Magic Money to pay for remote access to a
machine, use of a MUD, remailer, news posting service, etc.

Gambling - Accept bets on sports, the stock market, horses, etc.

This is the MGMNY11A release. That means it might have bugs. If you find
any, please post them on Cypherpunks@toad.com or alt.security.pgp. These 
are also good places to announce your service, or to contact me.

					  Pr0duct Cypher

			  "One line of code is worth a thousand rants."

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