Natural Language Steganography and an AI-complete Security Primitive - PowerPoint PPT Presentation

Motivation What happens if Wendy the warden intercepts a secure cryptogram? Serious consequences! • the greedy employer will fire Alice and Bob • the evil government will send Alice and Bob to Guantanomo Bay Natural Language Steganography and an “AI-complete” Security Primitive – p.36/182

Motivation What happens if Wendy the warden intercepts a secure cryptogram? Serious consequences! • the greedy employer will fire Alice and Bob • the evil government will send Alice and Bob to Auschwitz Natural Language Steganography and an “AI-complete” Security Primitive – p.37/182

Motivation What happens if Wendy the warden intercepts a secure cryptogram? Serious consequences! As long as there is a way for Wendy to tell ciphertext from cleartext, Alice and Bob will not live in peace! Natural Language Steganography and an “AI-complete” Security Primitive – p.38/182

Motivation What happens if Wendy the warden intercepts a secure cryptogram? Serious consequences! As long as there is a way for Wendy to tell ciphertext from cleartext, Alice and Bob will not live in peace! Solution: Alice and Bob must use steganographic methods, rather than purely cryptographic ones, in order to hide not only the content of a message from the adversary, but its very existence! Natural Language Steganography and an “AI-complete” Security Primitive – p.39/182

Motivation The difference between a cryptogram and a steganogram, is that a steganogram always appears innocuous to Wendy. Natural Language Steganography and an “AI-complete” Security Primitive – p.40/182

Introduction The difference between a cryptogram and a steganogram, is that a steganogram always appears innocuous to Wendy. But what is innocuous ? Natural Language Steganography and an “AI-complete” Security Primitive – p.41/182

Introduction The difference between a cryptogram and a steganogram, is that a steganogram always appears innocuous to Wendy. But what is innocuous ? In the simplest case Wendy has a list of innocuous cover symbols. Natural Language Steganography and an “AI-complete” Security Primitive – p.42/182

Introduction { Midshires is a nice little city , C = Midshires is a great little city , Midshires is a fine little city , Midshires is a decent little city , Midshires is a wonderful little city , Midshires is a nice little town , Midshires is a great little town } . If c ∈ C , then Wendy knows that c is innocuous. Natural Language Steganography and an “AI-complete” Security Primitive – p.43/182

Introduction { I don’t like my government! , M = I don’t like my internet provider! , I don’t like my employer! , I’m wearing ladies’ underwear! } . Alice wants to send Bob a message m ∈ M . Natural Language Steganography and an “AI-complete” Security Primitive – p.44/182

Introduction Instead of enlisting C = { Midshires is a ... } : • We know an innocuous sentence c = { Midshires is a nice little town , } • We have a dictionary, that tells us that the words { nice , great , fine , decent , wonderful } and { city , town } are synonymous , i.e. mean the same. • We know that, by substituting a word in c by a synonym, we never make an innocuous sentence suspicious, since we do not alter its meaning. Natural Language Steganography and an “AI-complete” Security Primitive – p.45/182

Introduction Instead of enlisting C = { Midshires is a ... } :   nice       great     � �   city   = Midshires is a fine little C town   decent         wonderful     Natural Language Steganography and an “AI-complete” Security Primitive – p.46/182

Introduction Instead of enlisting M = { I don’t like ... } : • We assume that Alice and Bob will exchange arbitrary bitstrings, so M = { 0 , 1 } ∗ Natural Language Steganography and an “AI-complete” Security Primitive – p.47/182

Alice and Bob Fool Wendy   00 nice       01 great     � �   0 city   Midshires is a 10 fine little . 1 town   11 decent         ?? wonderful     • m 1 = 101 encodes to c 1 = Midshires is a fine little town • m 2 = 010 encodes to c 2 = Midshires is a great little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.48/182

Alice and Bob Fool Wendy   00 nice       01 great     � �   0 city   Midshires is a 10 fine little . 1 town   11 decent         ?? wonderful     Keith Winstein and Mark Chapman have actually built variants of this system. Natural Language Steganography and an “AI-complete” Security Primitive – p.49/182

Wendy Strikes Back Statistic characteristics of the secret message “show trough” to the word-choices in the steganogram! Natural Language Steganography and an “AI-complete” Security Primitive – p.50/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 0 = 101 • m 1 = 001 • m 2 = 111 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.51/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 1 = 001 • m 2 = 111 • m 3 = 101 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.52/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 2 = 111 • m 3 = 101 • m 4 = 000 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.53/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 3 = 101 • m 4 = 000 • m 5 = 010 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.54/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 4 = 000 • m 5 = 010 • m 6 = 000 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.55/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 5 = 010 • m 6 = 000 • m 7 = 010 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.56/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 6 = 000 • m 7 = 010 • m 8 = 100 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.57/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 7 = 010 • m 8 = 100 • m 9 = 110 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.58/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 8 = 100 • m 9 = 110 • m 10 = 111 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.59/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 9 = 110 • m 10 = 111 • m 11 = 100 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.60/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 10 = 111 • m 11 = 100 • m 12 = 111 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.61/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 11 = 100 • m 12 = 111 • m 13 = 011 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.62/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 12 = 111 • m 13 = 011 • m 14 = 011 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.63/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 13 = 011 • m 14 = 011 • m 15 = 000 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.64/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 14 = 011 • m 15 = 000 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.65/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • m 15 = 000 • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.66/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.67/182

Wendy Strikes Back Innocuous covers have statistic characteristics originating from the way native speakers use the language. Natural Language Steganography and an “AI-complete” Security Primitive – p.68/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 0 = Midshires is a nice little town • c 1 = Midshires is a nice little city • c 2 = Midshires is a nice little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.69/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 1 = Midshires is a nice little city • c 2 = Midshires is a nice little town • c 3 = Midshires is a nice little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.70/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 2 = Midshires is a nice little town • c 3 = Midshires is a nice little town • c 4 = Midshires is a nice little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.71/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 3 = Midshires is a nice little town • c 4 = Midshires is a nice little city • c 5 = Midshires is a great little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.72/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 4 = Midshires is a nice little city • c 5 = Midshires is a great little city • c 6 = Midshires is a nice little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.73/182

Wendy Strikes Back   00 nice |||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 5 = Midshires is a great little city • c 6 = Midshires is a nice little town • c 7 = Midshires is a decent little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.74/182

Wendy Strikes Back   00 nice |||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 6 = Midshires is a nice little town • c 7 = Midshires is a decent little town • c 8 = Midshires is a great little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.75/182

Wendy Strikes Back   00 nice ||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 7 = Midshires is a decent little town • c 8 = Midshires is a great little town • c 9 = Midshires is a nice little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.76/182

Wendy Strikes Back   00 nice ||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 8 = Midshires is a great little town • c 9 = Midshires is a nice little town • c 10 = Midshires is a wonderful little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.77/182

Wendy Strikes Back   00 nice ||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 9 = Midshires is a nice little town • c 10 = Midshires is a wonderful little town • c 11 = Midshires is a great little town • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.78/182

Wendy Strikes Back   00 nice |||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 10 = Midshires is a wonderful little town • c 11 = Midshires is a great little town • c 12 = Midshires is a great little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.79/182

Wendy Strikes Back   00 nice |||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||    • c 11 = Midshires is a great little town • c 12 = Midshires is a great little city • c 13 = Midshires is a fine little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.80/182

Wendy Strikes Back   00 nice |||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    • c 12 = Midshires is a great little city • c 13 = Midshires is a fine little city • c 14 = Midshires is a nice little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.81/182

Wendy Strikes Back   00 nice |||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    • c 13 = Midshires is a fine little city • c 14 = Midshires is a nice little city • c 15 = Midshires is a fine little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.82/182

Wendy Strikes Back   00 nice |||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    • c 14 = Midshires is a nice little city • c 15 = Midshires is a fine little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.83/182

Wendy Strikes Back   00 nice ||||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    • c 15 = Midshires is a fine little city • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.84/182

Wendy Strikes Back   00 nice ||||||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    • ... Natural Language Steganography and an “AI-complete” Security Primitive – p.85/182

Wendy Strikes Back   00 nice ||||       01 great ||||     � �   0 city ||||||||   is a 10 fine little |||| . 1 town ||||||||   11 decent ||||         ?? wonderful  ||||      00 nice ||||||||       01 great ||||     � �   0 city ||||||||   is a little 10 fine . |||| 1 town |||||||||   11 decent ||||         ?? wonderful  ||||    Natural Language Steganography and an “AI-complete” Security Primitive – p.86/182

Alice, Bob, and Huffman This weakness is due to our use of block codes! Natural Language Steganography and an “AI-complete” Security Primitive – p.87/182

Alice, Bob, and Huffman 00 101110110010111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.88/182

Alice, Bob, and Huffman 00 10 1110110010111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.89/182

Alice, Bob, and Huffman 0010 11 10110010111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.90/182

Alice, Bob, and Huffman 001011 10 110010111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.91/182

Alice, Bob, and Huffman 00101110 11 0010111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.92/182

Alice, Bob, and Huffman 0010111011 00 10111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.93/182

Alice, Bob, and Huffman 001011101100 10 111001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.94/182

Alice, Bob, and Huffman 00101110110010 11 1001011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.95/182

Alice, Bob, and Huffman 0010111011001011 10 01011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.96/182

Alice, Bob, and Huffman 001011101100101110 01 011100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.97/182

Alice, Bob, and Huffman 00101110110010111001 01 1100010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.98/182

Alice, Bob, and Huffman 0010111011001011100101 11 00010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.99/182

Alice, Bob, and Huffman 001011101100101110010111 00 010100 |||||||| 00 |||||||| 01 |||||||| 10 |||||||| 11 Natural Language Steganography and an “AI-complete” Security Primitive – p.100/182