### Textbook Errata

Text: Trappe & Washington, Introduction to Cryptography with Coding Theory, 2nd Ed. Prentice-Hall, 2006

One of the authors maintains an errata list for this edition (it is a .pdf file, you will need to have Acrobat Reader installed to view it). Below you will find a copy of this errata list as of 9/24/2007. I will try to maintain it, but to be sure you should check the author's list. Errors that are not on the authors' list will be given below in red.

If you discover an error that is not on the list, you can e-mail it to me now using the subject line text error, and I will post it here and forward it to the authors.

In the list below, positive line numbers indicate from the top of the page, while negative ones indicate counting from the bottom of the page.

• pg. 24, line 5: insert "the" before "largest".
• pg. 24, line 19: change "For j = 1 to 25" to "For j = 0 to 25".
• pg. 42, lines 21-24: Comment: Since a one-way function could have constant last bit, this method might not yield a psuedo-random sequence. However, in practice it works well. How is the random seed s chosen? Keystrokes, clock timings, and things like that are often used to produce seeds.
• pg. 49, line -15: the congruence should be bmxn+m -xn+m.
• pg. 49, line -14: the last term in the displayed equivalence should be bm-1xn+m-1.
• pg. 50, end of section 2.11: add "Also, several LFSRs can be combined nonlinearly and some of these LSFRs can have irregular clocking."
• pg. 60, Problem 8: the ciphertext should end in the middle of the next to last line with weiuk. Remove mvswr...vbel, which seems to have migrated from the second line of the ciphertext of Problem 7.
• pg. 64, line 14: The sentence should read "A number p > 1 whose only positive divisors are 1 and itself is called a prime number."
• pg. 70, line -9: change "positive or negative" to "positive, negative or zero".
• pg. 83, line -9 : change "(p)" to "(mod p-1)".
• pg. 91, Theorem, part 4: change "(mod n)" to "(mod 8)" (twice)
• pg. 114, lines 5-7: Comment: Biham and Shamir have published a differential cryptanalytic attack that beats exhaustive key search on the full 16 round DES.
• pg. 123, lines 12-14: See above comment.
• pg. 123, line -14: remove the space between 1s and the period.
• pg. 129, lines 12-13: change "differ by 2 bits" to "differ by at least 2 bits".
• pg. 134, last displayed equation: It should be "R56" and "R48".
• pg. 149, line 2: change "c1" to "C1".
• pg. 152: Comment: After Rijndael was selected to become the AES, the NIST editor of the FIPS document specifying AES decided to change the names of the layers. The official names are now SubBytes, ShiftRows, MixColumns and AddRoundKey.
• pg. 158, line -5: change "InvByteSub" in step 2 to "InvShiftRow" (or to "InvShiftRows").
• pg. 162, Problem 2(a): the values of W(4) = W(6) and W(5) = W(7) are switched.
• pg. 171, line 11: change "if" to "of".
• pg. 192, Problem 2(a): change "decryption modulus" to "decryption exponent".
• pg. 192, Problem 6: change "(mod p)" to "(mod n)" (3 times).
• pg. 195, Exercise 23: For simplicity, assume that gcd(12345, e) = 1.
• pg. 196, line 7: change "2703000" to "270300".
• pg. 209, line 17: change "(mod p) let" to "(mod p). Let".
• pg. 211, line -2: change "" to c.
• pg. 216, Exercise 12(a): Assume gcd(c,n) = 1 (otherwise the second list cannot be computed).
• pg. 220, line -5: change "Exercise 9" to "Exercise 7".
• pg. 222, lines 4-5: change "a function" to "an algorithm".
• pg. 231, line 8: change "probably is" to "probability is approximately".
• pg. 231, line 9: change "ie-/i!" to "approximately ie-/i!".
• pg. 234, line -13: change
• pg. 234, line -2: change
• pg. 239, line 9: change "x1, she is still" to "x0, she is still".
• pg. 246, line -5: remove period after "p - 2".
• pg. 247, line 2: add "(with 0 < r < p)" at the end of the line.
• pg. 249, first lines of section 9.3: change "is at least as long as" to "can be longer than".
• pg. 251, line 12: change "Exercise 9" to "Exercise 7".
• pg. 252, line -5: add "Assume gcd(r,p-1) is small.".
• pg. 253, line -8: remove "the".
• pg. 278, lines -4,-3: change "Alice" to "Bob" and change "Bob" to "Alice".
• pg. 282, line 7: change "form" to "from".
• pg. 289, line 3: change "Exercise 9" to "Exercise 7".
• pg. 370, line 16: change "(0,1)" to "(2,3)".
• pg. 373, line -11: change "(0,1)" to "(2,3)".
• pg. 374, line -7: indent part (f) less, and remove "]".
• pg. 403, line -9: change "B(c,t)" to "B(c,r)".
• pg. 412, line 17: change "(0,0,0,0,0)" to "(0,0,0,0)".