🚀 go-pugleaf

Does anyone out there have the Addison Weseley book on Adobe Type 1 
Font Format (the "White Book"?)?  I was reading page 62 which gives 
the algorithm used for encryption and ran something that I think is 
wrong (but sometimes I have to wonder about *my* thought processes 
<grin>).  Here's the problem:
 
The algorithm states that you need to:
 
     A. Assign the high order 8 bits of R to a temporary variable, T.
      
     B. Ecslusive-OR P with T, producing a ciphertext byte, C.
 
     C. Compute the next value of R by the formula ((C+R) x c1 + 
     c2) mod 65536, where c1 is 52845 (decimal) and c2 is 22719 
     (decimal). 
 
The code ('C') given to perform this algorithm is as follows:
 
     unsigned short int r; 
     unsigned short int c1;
     unsigned short int c2;
 
     unsigned char Encryp(plain) unsigned char plain;
     {unsigned char cipher;
     cipher = (plain ^ (r>>8);
     r = (chipher + r) * c1 + c2;
     return cipher;
     }
 
I think the line beginning r= should read:
 
     r = ((cipher + r) * c1 + c2) % 65536;
 
Or am I missing something?  I'd appreciate it if anyone who has 
this book would take a look at this page (and the following page 
concerning decryption which has an identical "typo" <?>) and let me 
know what you think.

Please reply via email (dd@netlink.cts.com) because I've been SWAMPED latel
y                                                                            
and haven't been able to keep up with the traffic here.

Thanx.


--                    
INTERNET:  dd@netlink.cts.com (Donna Druchunas)
UUCP:   ...!nosc!ryptyde!netlink!dd
NetLink Online Communications * Public Access in San Diego, CA (619) 435-6181