The Cracking of the Cipher Challenge 10 steps to £10,000 www.simonsingh.net
www.simonsingh.net “The most incomprehensible thing about the universe is that it is comprehensible.” Albert Einstein
We are 13.7 billion light-years We are 12 billion light-years from the edge of the from the edge, observable universe, That’s a guess, That’s a good estimate with well-defined error bars, No one can ever say it’s true, And with the available But I know that I will always information, I predict that I be with you. will always be with you
The Cracking of the Cipher Challenge 10 steps to £10,000 www.simonsingh.net
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THE 10 STAGES 1. Simple substitution 6. Playfair cipher 2. Caesar cipher 7. ADFGVX cipher 3. Homophonic cipher 8. Enigma cipher 4. Vigenère cipher 9. DES encryption 5. Book cipher 10. RSA simonsingh.net
STAGE 1 CIPHERTEXT BT JPX RMLX PCUV AMLX ICVJP IBTWXVR CI M LMT’R PMTN, MTN YVCJX CDXV MWMBTRJ JPX AMTNGXRJBAH UQCT JPX QGMRJXV CI JPX YMGG CI JPX HBTW’R QMGMAX; MTN JPX HBTW RMY JPX QMVJ CI JPX PMTN JPMJ YVCJX. JPXT JPX HBTW’R ACUTJXTMTAX YMR APMTWXN, MTN PBR JPCUWPJR … .. simonsingh.net
The start of the first page of Al-Kindi’s manuscript c. 850 AD simonsingh.net
LETTER FREQUENCIES simonsingh.net
UNUSUAL MESSAGE Today, by radio, and also on giant hoardings, a rabbi, an admiral notorious for his links to masonry, a trio of cardinals and a trio, too, of politicians inform us all of how our country now risks dying of starvation. simonsingh.net
STAGE 5: BOOK CIPHER TEXT 109 182 6 11 88 214 74 77 153 109 195 76 37 188 166 188 73 109 15 208 42 5 217 78 209 147 9 80 169 109 22 96 169 3 29 214 9 198 77 112 8 30 117 124 86 73 124 86 96 73 177 50 161 How does a book cipher work? 1. Pick a book and number the letters in it. It was the best of times it was the worst of times … 12 345 678 9… … 17 … 2. Substitute each letter in a message with matching number M e e t m e a t m i d n i g h t … 8 2 … 17 10 simonsingh.net
STAGE 8: ENIGMA CIPHER simonsingh.net
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Rotor order 3! = 6 Rotor orientations 26 3 = 17,576 Rotor turnover points 26 2 = 676 Plugboard options = 10 11 Total no. of keys = 10 19 simonsingh.net
STAGE 9: DATA ENCRYPTION STANDARD Formally published on 15 January, 1977 56 ‑ bit key ‑ 10 17 keys, less than Enigma. How does it work? 64 bit blocks split into 2 x 32 bits, L 0 & R 0 . R O is 'mangled' added to L O to create R 1 . R O becomes L 1 . Repeat 16 times, to give L 16 & R 16 , the ciphertext. Each round of mangling is different, according to key* No publicly known shortcuts. Must search key space. Even invulnerable against differential cryptanalysis. simonsingh.net
CIPHER CHALLENGE CALENDAR Stage 1 Sept 1999 The first 4 stages fell within a matter of days. A medical researcher and a schoolgirl (age 14) Stage 2 Sept 1999 simultaneously crack stages 1-4 and head the Stage 3 Sept 1999 leader board. Stage 4 Sept 1999 Stage 5 Dec 1999 Stages 6-8 are cracked within a couple of weeks, but nobody can crack stage 5. Stage 6 Dec 1999 Eventually, a Cambridge mathematician Stage 7 Dec 1999 discovers the key text and claims stages 1-8. Stage 8 Dec 1999 Stage 9 Apr 2000 Jim Gillogly cracks 1-4 & 6-9 early, but has to team up with John Palagyi to get stage 5. Stage 10 Oct 2000 ? simonsingh.net
STAGE 10: THE RSA CIPHER What is RSA? • Public key cryptography solves the key distribution problem. • A technique for sharing a secret between remote strangers. How does RSA work? • A mathematical padlock based on ease of multiplying versus the immense difficulty of factoring. • In this case you need to factor: 10742 78829 12665 65907 17841 12799 42116 61266 39217 94753 29458 88778 17210 35546 41509 80121 87903 38329 26235 28109 07506 72083 50494 19964 33143 42555 83344 01855 80898 94268 92463. • Would be the toughest cipher to be cracked in public. How do you factor giant numbers? simonsingh.net
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THE AMAZING JUGGLING SWEDES (a.k.a. the stealth Swedes: Fredrik Almgren, Gunnar Andersson, Torbjorn Granlund, Lars Ivansson, Staffan Ulfberg) • Set to work on stage 10, succeed in generating dependencies • No access to expensive supercomputers • Rewrite programme for Compaq quad processor ES40 system • Oct 5 they discover the two factors!!!!!! simonsingh.net
Triple Des Key 1 encrypt Key 1 encrypt Key 2 decrypt Key 1 encrypt Key 2 encrypt Single Des ! Key 1 decrypt simonsingh.net
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