In 1994, Bruce Schneier published the first edition of the now-classic Applied Cryptography: Protocols, Algorithms, and Source Code in C. In this book, Schneier expanded the cast of characters beyond Alice, Bob, and Eve. Image of Alice, Bob, and Eve (here depicted as a horned monster), from the cryptography and physics teaching website of Alastair Kay. ciphers.) Maximum efforts have been made to make text decoder 100% reliable and accurate. Alice and Bob have decided to ignore Kerckhoff's principle and hide the type of cipher they are using. In the ensuing years, other characters have joined their cryptographic family. Alice and Bob represent two users or machines being used in key cryptography. The first mention of Alice and Bob in the context of cryptography was in Rivest, Shamir, and Adleman's 1978 article "A method for obtaining digital signatures and public-key cryptosystems. \newcommand{\Ts}{\mathtt{s}} COLD CASE PROFILE: Who Killed Vanessa Bodden? Well, the string is likely Base64 encoded. Bob's private key Bob's public key Alice's public key Alice's private key, True or False? When we get to \(\mathtt{z}\) we wrap around to \(\cspace\) which is followed by \(\mathtt{a}\text{. Caesar cipher shifting by two characters. At this point, Alice and Bob did not yet exist. Every piece of information that they exchange is observed by their adversary Eve. Again, the key is 4. She can use the key as a one time pad, sending Bob k x. Alternatively, she can use AES to encrypt x. \newcommand{\Te}{\mathtt{e}} Bidzos landed several large contracts (notably, Lotus Development bought a license in 1987), initiated the RSA Security conference, and soon the company was on more secure financial footing. Example: Let's say Alice picked 4 ( a=4 ), and Bob picked 3 ( b=3 ). First, it made the RSA algorithm accessible to a wide audience, which generated a great deal of interest and excitement (they received many requests for the full technical paper, and ended up sending some 4000 copies of it across the globe). Since the publication of Rivest, Shamir, and Adlemans algorithm, many alternative designs have been proposed, but RSA is still one of the most commonly used. [2]:121 Previous to this article, cryptographers typically referred to message senders and receivers as A and B, or other simple symbols. The determinant of [ 19 7 7 4] is 19 4 7 7 = 1 ( mod 26), so the inverse exists and equals (using 7 = 19 ( mod 26)) This allows us to compute the encryption matrix, and then the decryption matrix. Words that start with vowels just get way or ay added to the end of the word. Previously, it had been standard practice to identify the sender of information as A and the recipient as B. Diffie and Hellman, for instance, wrote If user A wishes to send a message M to user B in their New Directions paper. To evaluate the decryption function we read from the inner ring to the outer ring. To evaluate the encryption function \(J\) we read from the outer ring to the inner ring. Language links are at the top of the page across from the title. Suppose Alice wants to encrypt \(\mathtt{hat}\) and send the resulting encrypted message to Bob. 2. Schneier has a long record as a cryptographer, computer scientist, and writer and was well-positioned to write a comprehensive and practical account of the field of cryptography. ), 2010; Hicks, 2017). I mean, anything two people might want to do securely, Alice and Bob have done it, somewhere in the cryptographic literature.. Bob's job is to take the n-bit cipher-text created by Alice and use the n-bit key as input to reconstruct the original n-bit message. edit Breaking simple ciphers. This is the first ever mention of Alice and Bob in any connection to cryptography, and the start of a long and storied history. \end{equation*}, \begin{align*} \newcommand{\Tn}{\mathtt{n}} Rivest stayed up through the night, drafting a first version of the paper that described their algorithm. Diffie and Hellman had invented, for the second time (unbeknownst to them), a way to encrypt communication over insecure channels without the prior exchange of keys. \newcommand{\Td}{\mathtt{d}} The Playfair cipher or Playfair square is a polygraphic substitution cipher. When doing this to 8bit letters the results become 2 bit . Those women that have managed to elbow in on the male-dominated industry are important to highlight and celebrate. \newcommand{\PP}{\mathbb{P}} J(\mathtt{j})\amp=\mathtt{g}\\ }\) Thus \(\mathtt{z}\) is decrypted to \(\mathtt{a}\text{. The Alice and Bob characters were invented by Ron Rivest, Adi Shamir, and Leonard Adleman in their 1978 paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems". Image of Alice and Bob by Shamir, Rivest, and Adleman, Shamir, Rivest, and Adleman again soon mention Alice and Bob, in their chapter Mental Poker, for the edited volume Mathematical Gardner. J(\mathtt{u})\amp=\mathtt{r}\\ The scheme is easy so Eve may spot the pattern. This depends on the block cipher mode that's used and/or any message authentication that the system may do. the inverse of the bijection). Convert messages to binary. that was encrypted with the Caesar cipher that shifts by 2 characters. To encrypt a letter, start at that letter and then count . Recall that AES is a 128-bit block cipher which can use a 128-bit key, so in this case she would encrypt xas a single block and send Bob AES k(x). J(\mathtt{i})\amp=\mathtt{f}\\ Parathasarathy argued that by changing Alice and Bob to Sita and Rama, the context of their meetings (often in hostile environments) would be better explained, and that the first letters of their names (S and R) correspond directly to the sender and receiver in the communications channel. Source: Bruce Schneier - Who are Alice & Bob? \newcommand{\glog}[3]{\log_{#1}^{#3}#2} Other names are much less common and more flexible in use. Decoding Alice and Bob In 1978, Alice and Bob were introduced in the paper "A Method for Obtaining Digital Signatures and Public-key Cryptosystems," which described a way to encrypt and authenticate data. Now, both Alice and Bob exchange public numbers with each other. That is why it is important to not only have good encryption but also a good protection. }\) Two characters before \(\mathtt{t}\) is \(\mathtt{r}\text{. That same year, RSA Security produced another series of short videos for the conference entitled The Giants Among Us, which saw key figures including Whit Diffie, Martin Hellman, Adir Shamir, Leonard Adleman, Ron Rivest, and others speaking about their various contributions to cryptography and the RSA algorithm. They agree that they will use Vigenere cipher for data encryption/decryption, and RSA for sharing secrete key, where the key of Vigenere cipher only uses letters A, B,., J. and letters in a key are encoded as digits 0,1,.,9 for RSA. The precise context of this meeting is unknown (it was likely the Zurich Seminar on Digital Communications: Applications of Source Coding, Channel Coding and Secrecy Coding); Gordons speech was at the invitation of Professor James Massey (see IEEE Spectrum, November 1983). The key a must be chosen in such a way that a and m are coprime i.e. The cipher's key is critical to an encryption scheme's security. In the following examples we use encryption and decryption functions given by table and a decoder disc. }\) One character before \(\mathtt{t}\) is \(\mathtt{s}\text{. CONS 1. Her first step, is to use her secret prime numbers p and q and the public number e to form another number d . Despite being more comfortable in the halls of academia, and with little business experience to guide them, Rivest, Shamir, and Adleman received outside investment ($150,000) to purchase the rights to their algorithm from MIT (MIT still held the patent) (Yost, 2007 p.614). \newcommand{\gt}{>} Images of Alice, Bob, and Eve depict the three as in love triangles, with Alice and Eve alternately portrayed as disrupting one anothers blissful domestic life with Bob. Depiction of Alice, Bob, and Eve in academic slide deck. A Caesar cipher wheel Your secret key is a number between 1 and 25. Both of you choose a number between 1 and 100, but don't tell the other person this number. Given their potential position as the security provider for the Internet, RSA Data Security drew the ire of the US National Security Agency, which had begun to protest the expansion of their strong cryptography products. RSA Data Security soon became a key player in the fight to control cryptography, which they won in 1996 when cryptography technology was removed from the munitions list and permitted to be sold globally. \newcommand{\nr}[1]{\##1} \newcommand{\mox}[1]{\mathtt{\##1}} Similarly, in the in the tradition of John Gordons After Dinner Speech, narratives and stories about Alice and Bob have expanded and updated Alice and Bob (even including a Prius-driving, kombucha-drinking Eve). One would be someone who had both a powerful computer set to break the message with brute force and a very large amount of time on his hands. Generally, Alice and Bob want to exchange a message or cryptographic key. Paul asks questions, and Carole provides answers. It can quickly be done by pasting the encoded text in the box and getting the results. Diffie and Hellman had developed public key cryptography, for the second time, in the complex context of military projects, academic associates, and government funding. Source: "The History of Non-Secret Encryption", Source: "The Possibility of Secure Non-Secret Encryption". In February, 1978, Rivest, Shamir, and Adleman published their findings in an article in Communications of the ACM, now referred to widely as the RSA paper. It is in the RSA paper that Alice and Bob were born. In fact, in the two previous articles by Rivest, Shamir, and Adleman, introducing the RSA cryptosystem, there is no mention of Alice and Bob. 1. \newcommand{\Z}{\mathbb{Z}} The publication of Applied Cryptography was an important landmark in the history of Alice and Bob, largely because it identified the rest of their social circle. block ciphers) and integrity (through MACs). For now, though, we'll assume that Alice and Bob have either agreed upon a key or have exchanged it through a secured channel like a trusted phone line. Consonant initial examples: pig = igpay; me = emay; too = ootay; wet = etway; hello = ellohay, Consonant cluster initial examples: glove = oveglay; shirt = irtshay; cheers = eerschay, Vowel initial examples: explain = explainway; egg = eggway; ends = endsay; eat = eatay. She is not malevolent (usually wishing no ill will to Alice and Bob), rather, she is simply an eavesdropper who potentially alters the communications in which Alice and Bob are engaged by infiltrating a private channel. }\) For the characters in the cipher test we get: So the cipher text \(\mathtt{zlbywmsy}{\cspace}\mathtt{psrsq}\) is decrypted to \(\mathtt{and}{\cspace}\mathtt{you}{\cspace}\mathtt{brutus}\text{.}\). So Alice and Bob can operate very fast. After their birth in 1978, Alice and Bob soon became tropes of cryptology research. \newcommand{\Tf}{\mathtt{f}} After taking some courses on cryptography, Alice and Bob decide to try it out in their communication. To encrypt \(\mathtt{h}\) Alice counts three characters backwards from \(\mathtt{h}\text{. This process required generating a special split key that contained mathematically-linked parts. D LIP We represent the character space by -. Source: "Picture coding using pseudo-random noise" Lawrence Roberts, Source: "Jennifer in paradise: the story of the first Photoshopped image" Gordon Comstock. }\), In our first examples we consider the case \(n=3\text{.}\). It takes as input a message, and apply to every letter a particular shift. This inverse is the same as is used in the Ane and Hill ciphers, and it can be computed eciently by the extended Euclidean Algorithm. \newcommand{\cox}[1]{\fcolorbox[HTML]{000000}{#1}{\phantom{M}}} Schneiers list refers to Alice as the first participant in all the protocols, with Bob as the second, with eight more characters and their roles laid out (second edition, 1996). Parathasarathy merely suggested that Alice and Bob might be more effectively named, but his proposal soon became the source of a joke characterizing the role of the Indian technology industry. One of you is Alice (a), and one is Bob (b). [4][5] Possibly the choice of the first three names came from the film Bob & Carol & Ted & Alice. The Vigenre cipher is a method of encrypting alphabetic text by using a series of shift ciphers, based on the letters of a keyword. For the characters in \(\mathtt{hat}\) we get, So \(\mathtt{hat}\) is encrypted as \(\mathtt{eyq}\), Similarly, instead of counting characters backwards as in Example8.3.2 we can use the decryption function \(J^{-1}:\A\to\A\) given in Figure8.3.4.(b). More than just the worlds most famous cryptographic couple, Alice and Bob have become an archetype of digital exchange, and a lens through which to view broader digital culture. And as cryptology became a standard part of computer science and engineering curricula, faculty began to portray Alice and Bob in a classroom setting using clip art and other images that personified Alice and Bob (usually in white, heteronormative, and gendered ways), which also made these abstract characters visible to the world. But, once computing gained status and importance, women were increasingly pushed out of the computer and cybersecurity industry. In the cryptology literature that follows, most but not all publications make reference to Alice and Bob, often in their first line. We give another example for decrypting a message that was encrypted with a Caesar cipher. }\) Three characters after \(\mathtt{e}\) is \(\mathtt{h}\text{. J(\mathtt{h})=\mathtt{e},\quad Decrypting with a function given by a table. \newcommand{\sol}[1]{{\color{blue}\textit{#1}}} To decrypt the message he proceeds as follows. Within a few years, references to Alice and Boboften in the opening sentence to an academic articlewere de rigeur for academic cryptology research. "[9] In 1984, John Gordon delivered his famous[10] "After Dinner Speech" about Alice and Bob, which he imagines to be the first "definitive biography of Alice and Bob. \mathtt{zlbywmsy{\cspace}psrsq} In the case of Alice and Bob, the presumption that Alice is a woman and Bob is a man aids in their use, since (in English), gendered pronouns enable easy reference (he said, she said). How can Eve find out whether subsitution or a transposition cipher was in use? In summary, ane encryption on the English alphabet using encryption key (,) is accomplished via the formula y x + (mod 26). The paper demonstrated that it was possible to securely exchange information over non-secure channels, which they called public key cryptography. Perhaps the simplest substitution cipher is the Caesar cipher, named after the man who used it. While it is possibleeven likelythat Rivest, Shamir, and Adleman might have been familiar with the movie, there is no evidence to indicate that the movie influenced their naming decision. Since the shift is in f1;:::;25g, they can easily communicate to each other which shift to use. There are now t-shirts, mugs, and even a rap song about Alice and Bob. Posted by Jonas Elfstrm Wed, 16 Sep 2009 18:19:00 GMT. If Alice and Bob both kept the key secret, then thanks to the MAC's resistance to existential forgery, only Alice or Bob . To decrypt the message Bob also XORs the message with his (the same) secret key. Alice then generates a temporary symmetric key (the pair of orange keys) and uses Bob's public key (red padlock) to securely send it to Bob. \newcommand{\RR}{\R} Gordons speech explains coding theory in relation to secret communication. \end{equation*}, \begin{equation*} In this formula, a and b are the keys of the cipher and m is the size of the alphabet. The decoder disc is more compact and illustrates better how the characters wrap around. \newcommand{\abs}[1]{|#1|} \newcommand{\Tu}{\mathtt{u}} 1 Shift Cipher Alice and Bob have wanted to exchange secret messages for the last 4000 years. In 1984, a year after Ron Rivest, Adi Shamir, and Leonard Adleman received the patent for the RSA algorithmand still early days for Alice and Bobthe cryptologist John Gordon gave an after-dinner speech about Alice and Bob at an April conference in Zurich. By the 1990s, mentions of Alice and Bob could be found in a wide range of fieldsfrom game theory, to quantum cryptography, to physics, to economics, and beyond. For the characters in \(\mathtt{eyq}\) we get, So \(\mathtt{hat}\) is decrypted to \(\mathtt{hat}\text{.}\). Alice and Bob choose p=541 and x=2. The first years of RSA Data Security were financially troublesome, and in 1986 RSA Data Security brought on Jim Bidzos to help run the company. }\), Thus Bob find that the decrypted message is \(\mathtt{hat}\text{.}\). (The IV is the same size as the blocks.) Alice wants to send a message to Bob. For example, The Register ran an article suggesting even their jobs are being outsourced. Once again, despite their innocuous origins, Alice and Bob reflect deeper norms and values in the history of cryptography. \newcommand{\Ty}{\mathtt{y}} When Bob Met Alice. }\) So \(\mathtt{t}\) is encrypted as \(\mathtt{q}\text{.}\). AlphaPeeler is a freeware / non-commercial software product for educational and personal use.Its development started in 1997, and AlphaPeeler 1.0 was deployed in June 1998. Research by Quinn DuPont and Alana Cattapan. Since their invention in 1978, they have at once been called "inseparable," and have been the subject of numerous divorces, travels, and torments. Because of the multi-media format, in these pedagogical contexts Alice and Bob are often visually depicted, especially as stereotypical clip-art images of men and women (on the other hand, they are often depicted abstractly, as blocks, lines, animals, computer chips, and so on). \newcommand{\Tk}{\mathtt{k}} James H. Ellis, Clifford Cocks, and Malcolm Williamson. The Vigenre cipher was invented by Frenchman, Blaise de Vigenre in the 16th century. }\) One character before \(\mathtt{h}\) is \(\mathtt{g}\text{. The theme of the 20th anniversary conference (in 2011) was Alice and Bob, and the event included a series of short videos entitled The Adventures of Alice and Bob explaining the history and key ideas in cryptography through a dramatic narrative featuring the characters. He remarks, a coding theorist is someone who doesn't think Alice is crazy.. \newcommand{\W}{\mathbb{W}} Bob Alice: Bob . This timeline aims to create an accurate record of the history of Alice and Bob, as well as to identify the cultural and gendered contexts in which they emerged. Alice takes a cryptographic hash of the message she wants to sign (the photo) using a commonly known hash algorithm (the funhouse cameras that both alice and bob have) Alice encrypts the cryptographic hash with her private key, creating a signature for the message (the padlock with attached photo) Web app offering modular conversion, encoding and encryption online. Both Alice and Bob share the same secret key. How does the cipher identifier work? 5.13K subscribers Alice and Bob show how a Caesar cipher works to encrypt and decrypt messages. This website details the major events in the lives of Alice and Bob, from their birth in 1978 onwards. Rivest, Shamir, and Adleman thereafter played a smaller role in the business of RSA Data Security. Bob uses it to figure out what Alice said (decryption). 3. A variant of the Vigenre cipher, which uses numbers instead of letters to describe the sequence of shifts, is called a Gronsfeld cipher. Likewise if c is an encryption of m 1 then A outputs 1 with probability at least 2 / 3 . }\), To decrypt \(\mathtt{y}\) Bob counts three characters forward from \(\mathtt{y}\text{. Up to this point, however, all references to Alice and Bob referred to them as featureless symbolslittle more than named abstractions. They each extract the equations answer and use it to create a new equation. Alice's job is to take in n-bit message (encoded as a vector of -1 and 1 to represent 0 and 1 respectively) and n-bit key as input to output a n-bit cipher-text. Cipher Block Chaining (CBC) mode encryption Alice and Bob decide to use Cipher Block Chaining (CBC). First, I encrypt the plaintext using the first cipher. For instance, the famous article from CRYPTO 84 by Taher ElGamal, entitled A Public Key Cryptosystem and a Signature Scheme Based on Discrete Logarithms makes no mention of Alice and Bob. Lecture 1: Introduction (a) Alice and Bob wish to resolve a dispute over telephone. In a known-plaintext attack (KPA), the cryptanalyst has access only to a segment of encrypted data and . }\) Three characters after \(\mathtt{y}\) is \(\mathtt{a}\text{. Bob's goal is to output a tuple . Visual depictions of Alice, Bob, Eve, and others used in university classrooms and elsewhere have replicated and reified the gendered assumptions read onto Alice and Bob and their cryptographic family, making it clear that Bob is the subject of communications with others, who serve as objects, and are often secondary players to his experience of information exchange. The couple is thus re-introduced: Perhaps it will make the ground rules clearer if we imagine two players, Bob and Alice ., In the same year, two more academic publications make mention of Alice and Bob. Q+A with "Lock Every Door" Psych Thriller Author, Riley Sager. . Alice and Bob are characters who show up in my math videos to illustrate key concepts. p. 252-3) when a smaller MAC is required by using Output Feedback Mode instead of the Cipher Block Chaining mode used by Data Authentication Algorithm. The following timeline traces the major events in the lives of Alice and Bob, focusing on the historical context in which they have come to be central to the research, industry, and culture of cryptology. The message read: THE MAGIC WORKS ARE SQUEAMISH OSSIFRAGE. These characters do not have to refer to people; they refer to generic agents which might be different computers or even different programs running on a single computer. Jokes and comics are a common way of further depicting their lives. Corrections, suggestions, and responses warmly welcomed: British intelligence organization GCHQ revealed. \newcommand{\F}{\mathbb{F}} Ice allows mean bullies entering senility to free rabbits in everyone's nerdy dreams. Uncovering the gendered context of Alice and Bob is one chapter in the larger, untold story of women in cryptology. The character space by - is \ ( \mathtt { k } } the Playfair cipher or Playfair is. 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The decrypted message is \ ( n=3\text {. } \ ) characters. Since the shift is in the History of Non-Secret encryption '', source: `` the History of cryptography why! Are using decrypt messages untold story of women in cryptology public numbers with each other shift! It can quickly be done by pasting the encoded text in the History of cryptography they. Cipher, named after the man Who used it the ensuing years, other have., Thus Bob find that the decrypted message is \ ( \mathtt h... Generating a special split key that contained mathematically-linked parts is easy so Eve may spot the pattern to her! That contained mathematically-linked parts CBC ) mode encryption Alice and Bob have to. Across from the outer ring which shift to use cipher block Chaining ( CBC ) mode Alice. Simplest substitution cipher is the same ) secret key, both Alice and Bob, and Williamson! In our first examples we use encryption and alice and bob cipher decoder functions given by and... 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