commit 2cfff88329e624f4cfa37a7819b101a8f24e5f3c
parent 66a708c4cb022a38329ca0a338c4865af77bad64
Author: Jared Tobin <jared@jtobin.ca>
Date: Sun, 14 May 2017 00:13:16 +1200
Docs.
Diffstat:
| M | README.md | | | 199 | +------------------------------------------------------------------------------ |
| A | docs/s1.md | | | 178 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| A | docs/s2.md | | | 20 | ++++++++++++++++++++ |
3 files changed, 200 insertions(+), 197 deletions(-)
diff --git a/README.md b/README.md
@@ -7,201 +7,6 @@ in [Rust](https://www.rust-lang.org) and [Haskell](https://haskell-lang.org/).
## Problems
-### Set 1
-
-#### 1.1
-
- $ SOLUTION=$(cat data/s1/q1_input.txt | ./bin/hex2b64)
- $ diff <(echo $SOLUTION) data/s1/q1_output.txt
-
-One could write no code at all:
-
- $ xxd -r -p data/s1/q1_input.txt | base64
-
-It's also fun to check the ASCII-encoded input:
-
- $ xxd -r -p data/s1/q1_input.txt
- I'm killing your brain like a poisonous mushroom
-
-#### 1.2
-
- $ SOLUTION=$(./bin/fixed_xor $(< data/s1/q2_input.txt) $(< data/s1/q2_against.txt))
- 746865206b696420646f6e277420706c6179
-
-ASCII-encoded output is fun:
-
- $ echo $SOLUTION | xxd -r -p
- the kid don't play
-
-**Background**:
-
-Fixed-xor just encrypts by XOR'ing every bit with some corresponding bit.
-Example:
-
- echo -n 'FAB' | xxd -b && echo -n 'ICE' | xxd -b
- 00000000: 01000110 01000001 01000010 FAB
- 00000000: 01001001 01000011 01000101 ICE
-
-So XOR-ing 'FAB' with 'ICE' can be done manually:
-
- 0100 0110 0100 0001 0100 0010
- 0100 1001 0100 0011 0100 0101
-
- 0000 1111 0000 0010 0000 0111
-
-So in hex that's '0f0207':
-
- $ echo 'obase=16; ibase=2; 000011110000001000000111' | bc
- F0207
-
-You can play things back like so to confirm:
-
- $ ./bin/fixed_xor '0f0207' $(echo -n ICE | xxd -p) | xxd -r -p
- FAB
-
-#### 1.3
-
- $ ./bin/charfreq $(< data/s1/q3_input.txt)
- original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
- byte (frequency)
- ----------------
- 120 (6)
- 55 (5)
- 54 (3)
- 49 (2)
- 27 (2)
-
- $ cat data/s1/q3_input.txt | ./bin/single_byte_xor 120
- original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
-
- xored with: 120 (x)
- decrypted: cOOKINGmcSLIKEAPOUNDOFBACON
-
-Here it's worth noting that you can usually get a better decryption by using
-the opposite case, so (ASCII-encoded +- 32):
-
- $ cat data/s1/q3_input.txt | ./bin/single_byte_xor 88
- original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
-
- xored with: 88 (X)
- decrypted: Cooking MC's like a pound of bacon
-
-#### 1.4
-
- $ parallel -a data/s1/q4_input.txt ./bin/charfreq | less
-
-Look for strings w/high-frequency bytes and you'll find the following
-w/five hits of ASCII-encoded 21. There's another input in which ']' gets five
-hits, but it doesn't seem to decrypt to anything.
-
- $ INPUT=7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
- $ HIGH_FREQ_BYTE=21
- $ echo $INPUT | ./bin/single_byte_xor $HIGH_FREQ_BYTE
- original: 7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
-
- xored with: 21 ()
- decrypted: nOWTHATTHEPARTYISJUMPING*
-
-Similar here, using 21 + 32:
-
- $ echo $INPUT | ./bin/single_byte_xor 53
- original: 7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
-
- xored with: 53 (5)
- decrypted: Now that the party is jumping
-
-#### 1.5
-
- $ echo -n $(< data/s1/q5_input.txt) | ./bin/repeating_key_xor ICE | fold -w 74
- original:
- Burning 'em, if you ain't quick and nimble I go crazy when I hear a cymbal
- xored with: ICE
- result:
- 0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a2622632427276527
- 2a282b2f20690a652e2c652a3124333a653e2b2027630c692b20283165286326302e27282f
-
-Can check this by grabbing the result under 'INPUT' and xor-ing it again:
-
- $ xxd -r -p <<< $INPUT | ./bin/repeating_key_xor ICE | xxd -r -p | less
-
-#### 1.6
-
- $ INPUTB64=$(< data/s1/q6_input.txt)
- $ INPUTHEX=$(echo $INPUTB64 | ./bin/b642hex)
- $ echo $INPUTB64 | ./bin/score_keysizes 4 10
-
-Top keysizes for average of 4+ groups are roughly 5, 29, 3.
-
-Five doesn't go far:
-
- $ KEYSIZE=5
- $ echo $INPUTHEX | ./bin/rotate $KEYSIZE | parallel -k ./bin/charfreq | less
-
-Twenty-nine does it:
-
- $ KEYSIZE=29
- $ echo $INPUTHEX | ./bin/rotate $KEYSIZE | parallel -k ./bin/charfreq | less
- $ xxd -r -p <<< "$INPUTHEX" | \
- ./bin/repeating_key_xor "tERMINATOR x bRING THE NOISE" | \
- xxd -r -p | less
-
-Shift by 32 for readability:
-
- $ xxd -r -p <<< "$INPUTHEX" | \
- ./bin/repeating_key_xor "Terminator X: Bring the noise" | \
- xxd -r -p | less
-
-#### 1.7
-
-I like openssl, heck the rules:
-
- $ KEY=$(echo -n 'YELLOW SUBMARINE' | xxd -p)
- $ openssl enc -aes-128-ecb \
- -a -d -K $KEY -nosalt \
- -in data/s1/q7_input.txt | head -2
- I'm back and I'm ringin' the bell
- A rockin' on the mike while the fly girls yell
-
-Alternatively:
-
- $ cat data/s1/q7_input.txt | tr -d '\n' | ./bin/aes_ecb | head -2
- 'm back and I'm ringin' the bell
- A rockin' on the mike while the fly girls yell
-
-NB. missing the initial 'I' there for some reason.
-
-#### 1.8
-
- $ cat data/s1/q8_input.txt | parallel \
- 'echo -n {} | ./bin/chunks 8 | printf "%.10s %u\n" {} \
- $(datamash countunique 1)' | awk '{ if ($2 < 20) { print }; }'
- d880619740 14
-
-So, the line starting with 'd880619740' - line 133.
-
-**Background**:
-
-ECB means electronic codebook, the simplest block cipher encryption mode. One
-divides a message into 16-byte chunks and then encrypts each chunk separately.
-The same 16 bytes will thus encrypt to the same output.
-
-### Set 2
-
-#### 2.1
-
- $ echo -n 'YELLOW SUBMARINE' | ./bin/pkcs 20 | xxd
- 00000000: 5945 4c4c 4f57 2053 5542 4d41 5249 4e45 YELLOW SUBMARINE
- 00000010: 0404 0404 0a .....
-
-#### 2.2
-
- $ KEY=$(echo -n 'YELLOW SUBMARINE' | xxd -p)
- $ openssl enc -aes-128-cbc \
- -a -d -K $KEY -nosalt -iv 0 \
- -in data/s2/q10_input.txt | head -2
- I'm back and I'm ringin' the bell
- A rockin' on the mike while the fly girls yell
-
-The problem description says NO OPENSSL, but I don't actually have much
-experience with openssl, so it's fun to check out.
+* [Problem Set 1](docs/s1.md)
+* [Problem Set 2](docs/s2.md)
diff --git a/docs/s1.md b/docs/s1.md
@@ -0,0 +1,178 @@
+### Set 1
+
+#### 1.1
+
+ $ SOLUTION=$(cat data/s1/q1_input.txt | ./bin/hex2b64)
+ $ diff <(echo $SOLUTION) data/s1/q1_output.txt
+
+One could write no code at all:
+
+ $ xxd -r -p data/s1/q1_input.txt | base64
+
+It's also fun to check the ASCII-encoded input:
+
+ $ xxd -r -p data/s1/q1_input.txt
+ I'm killing your brain like a poisonous mushroom
+
+#### 1.2
+
+ $ SOLUTION=$(./bin/fixed_xor $(< data/s1/q2_input.txt) $(< data/s1/q2_against.txt))
+ 746865206b696420646f6e277420706c6179
+
+ASCII-encoded output is fun:
+
+ $ echo $SOLUTION | xxd -r -p
+ the kid don't play
+
+**Background**:
+
+Fixed-xor just encrypts by XOR'ing every bit with some corresponding bit.
+Example:
+
+ echo -n 'FAB' | xxd -b && echo -n 'ICE' | xxd -b
+ 00000000: 01000110 01000001 01000010 FAB
+ 00000000: 01001001 01000011 01000101 ICE
+
+So XOR-ing 'FAB' with 'ICE' can be done manually:
+
+ 0100 0110 0100 0001 0100 0010
+ 0100 1001 0100 0011 0100 0101
+
+ 0000 1111 0000 0010 0000 0111
+
+So in hex that's '0f0207':
+
+ $ echo 'obase=16; ibase=2; 000011110000001000000111' | bc
+ F0207
+
+You can play things back like so to confirm:
+
+ $ ./bin/fixed_xor '0f0207' $(echo -n ICE | xxd -p) | xxd -r -p
+ FAB
+
+#### 1.3
+
+ $ ./bin/charfreq $(< data/s1/q3_input.txt)
+ original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
+ byte (frequency)
+ ----------------
+ 120 (6)
+ 55 (5)
+ 54 (3)
+ 49 (2)
+ 27 (2)
+
+ $ cat data/s1/q3_input.txt | ./bin/single_byte_xor 120
+ original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
+
+ xored with: 120 (x)
+ decrypted: cOOKINGmcSLIKEAPOUNDOFBACON
+
+Here it's worth noting that you can usually get a better decryption by using
+the opposite case, so (ASCII-encoded +- 32):
+
+ $ cat data/s1/q3_input.txt | ./bin/single_byte_xor 88
+ original: 1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736
+
+ xored with: 88 (X)
+ decrypted: Cooking MC's like a pound of bacon
+
+#### 1.4
+
+ $ parallel -a data/s1/q4_input.txt ./bin/charfreq | less
+
+Look for strings w/high-frequency bytes and you'll find the following
+w/five hits of ASCII-encoded 21. There's another input in which ']' gets five
+hits, but it doesn't seem to decrypt to anything.
+
+ $ INPUT=7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
+ $ HIGH_FREQ_BYTE=21
+ $ echo $INPUT | ./bin/single_byte_xor $HIGH_FREQ_BYTE
+ original: 7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
+
+ xored with: 21 ()
+ decrypted: nOWTHATTHEPARTYISJUMPING*
+
+Similar here, using 21 + 32:
+
+ $ echo $INPUT | ./bin/single_byte_xor 53
+ original: 7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f
+
+ xored with: 53 (5)
+ decrypted: Now that the party is jumping
+
+#### 1.5
+
+ $ echo -n $(< data/s1/q5_input.txt) | ./bin/repeating_key_xor ICE | fold -w 74
+ original:
+ Burning 'em, if you ain't quick and nimble I go crazy when I hear a cymbal
+ xored with: ICE
+ result:
+ 0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a2622632427276527
+ 2a282b2f20690a652e2c652a3124333a653e2b2027630c692b20283165286326302e27282f
+
+Can check this by grabbing the result under 'INPUT' and xor-ing it again:
+
+ $ xxd -r -p <<< $INPUT | ./bin/repeating_key_xor ICE | xxd -r -p | less
+
+#### 1.6
+
+ $ INPUTB64=$(< data/s1/q6_input.txt)
+ $ INPUTHEX=$(echo $INPUTB64 | ./bin/b642hex)
+ $ echo $INPUTB64 | ./bin/score_keysizes 4 10
+
+Top keysizes for average of 4+ groups are roughly 5, 29, 3.
+
+Five doesn't go far:
+
+ $ KEYSIZE=5
+ $ echo $INPUTHEX | ./bin/rotate $KEYSIZE | parallel -k ./bin/charfreq | less
+
+Twenty-nine does it:
+
+ $ KEYSIZE=29
+ $ echo $INPUTHEX | ./bin/rotate $KEYSIZE | parallel -k ./bin/charfreq | less
+ $ xxd -r -p <<< "$INPUTHEX" | \
+ ./bin/repeating_key_xor "tERMINATOR x bRING THE NOISE" | \
+ xxd -r -p | less
+
+Shift by 32 for readability:
+
+ $ xxd -r -p <<< "$INPUTHEX" | \
+ ./bin/repeating_key_xor "Terminator X: Bring the noise" | \
+ xxd -r -p | less
+
+#### 1.7
+
+I like openssl, heck the rules:
+
+ $ KEY=$(echo -n 'YELLOW SUBMARINE' | xxd -p)
+ $ openssl enc -aes-128-ecb \
+ -a -d -K $KEY -nosalt \
+ -in data/s1/q7_input.txt | head -2
+ I'm back and I'm ringin' the bell
+ A rockin' on the mike while the fly girls yell
+
+Alternatively:
+
+ $ cat data/s1/q7_input.txt | tr -d '\n' | ./bin/aes_ecb | head -2
+ 'm back and I'm ringin' the bell
+ A rockin' on the mike while the fly girls yell
+
+NB. missing the initial 'I' there for some reason.
+
+#### 1.8
+
+ $ cat data/s1/q8_input.txt | parallel \
+ 'echo -n {} | ./bin/chunks 8 | printf "%.10s %u\n" {} \
+ $(datamash countunique 1)' | awk '{ if ($2 < 20) { print }; }'
+ d880619740 14
+
+So, the line starting with 'd880619740' - line 133.
+
+**Background**:
+
+ECB means electronic codebook, the simplest block cipher encryption mode. One
+divides a message into 16-byte chunks and then encrypts each chunk separately.
+The same 16 bytes will thus encrypt to the same output.
+
diff --git a/docs/s2.md b/docs/s2.md
@@ -0,0 +1,20 @@
+### Set 2
+
+#### 2.1
+
+ $ echo -n 'YELLOW SUBMARINE' | ./bin/pkcs 20 | xxd
+ 00000000: 5945 4c4c 4f57 2053 5542 4d41 5249 4e45 YELLOW SUBMARINE
+ 00000010: 0404 0404 0a .....
+
+#### 2.2
+
+ $ KEY=$(echo -n 'YELLOW SUBMARINE' | xxd -p)
+ $ openssl enc -aes-128-cbc \
+ -a -d -K $KEY -nosalt -iv 0 \
+ -in data/s2/q10_input.txt | head -2
+ I'm back and I'm ringin' the bell
+ A rockin' on the mike while the fly girls yell
+
+The problem description says NO OPENSSL, but I don't actually have much
+experience with openssl, so it's fun to check out.
+
