• on Computer/Software/Internet
  • Published in issue 10/2005 on page 0
About the article

Colossus Jr.

A data authenticator

Colossus Jr.
Cryptography is usually thought of as concerned only with keeping secrets, but there is another use for cryptography, which has more to do with keeping things in the open. This other use, which rightly belongs in this issue on All Things Security, is data authentication: techniques for verifying that data has not been tampered with.
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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Resistors:
R1,R4,R6,R7 = 22k
R2 = 10k
R3,R5 = 2k2
R8 = 270
Capacitors:
C1 = 100nF
C2 = 22µF 16V radial
C3,C4 = 10µF 16V radial
Semiconductors:
D1 = 1N4148
T1,T2 = BC557B
T3 = BC547B
IC1 = PIC12F675-C/P, programmed. Publishers order code 040267-41*
IC2 = 7805CP
Miscellaneous:
K1 = 9-way sub-D socket (female), PCB edge mounting
K2 = 5-way SIL pinheader
Res1 = 8.000MHz ceramic resonator
8-way IC socket
RS232 serial cable (non-crossed)
PCB, ref. 040267-1 from The PCBShop
PIC source code files, code 040267-11
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