Thank you Michael Rabin for your excellent work. Rest in Peace.
Rabin Fingerprinting is one of my favorites of his contributions. It's a "rolling hash" that allows you to quickly compute a 32-bit (or larger) hash at *every* byte offset of a file. It is used most notably to do file block matching/deduplication when those matching blocks can be at any offset. It's tragically underappreciated.
I've been meaning to write up a tutorial as part of my Galois Field series. Someday..
I recently found his fingerprint algorithm and wrote a utility that uses it to find duplicate MIPS code for decompilation[0] and build unique identifiers that can be used to find duplicates without sharing any potentially copyrighted data[1].
This replaced some O(n²) searches through ASCII text, reducing search time from dozens of seconds to fractions of a second.
Important to note that FastCDC is about an order of magnitude for block deduplication and is generally considered the state of art for such an approach (speed of computing the hash is more important than absolutely optimal distribution of hashes).
I'm working on a data annotation system based around Rabin fingerprints. They're a really neat idea.
I especially like how if you end up with hash characteristics that you don't like, your can just select a different irreducible Galois polynomial and now you've got a whole new hash algorithm. It's like tuning to a different frequency.
For me it means I don't have to worry about cases where there aren't enough nearby fingerprints for the annotation to adhere to, I can just add or remove polynomials until I get a good density.
I wrote a Rabin—Karp implementation in ~2006 as part of the spam and threat scanning stack for the MX Logic mail service. It was incredibly performant, letting us test {n} bytes against an essentially unlimited number of string signatures in O(n) time.
I took his Introduction to Cryptography class when he was a visiting professor at Columbia. Absolute master of an old-school chalkboard lecturer. They don't make them like that any more.
I took his Computability class in the Hebrew University. He got angry that students were often late to class, and said that this never happened in Harvard...
For those interested in searching for more here's a Hebrew search string you can use: "פרופסור מיכאל רבין הרצאה" interesting enough Google and YT search yield results in English and Hebrew but possibly different ones than just searching in English.
I had the incredible good fortune to take one of his classes in college, and I loved it so much I took another just to learn from him again. A tremendous intellect AND an incredibly engaging and talented instructor. It would be an exaggeration to say that I knew him, but nevertheless he had a great impact on my education and my life. He will be missed.
I took a course from him as a graduate student. I was not (and am still not) a theoretician. But I enjoyed the class and Professor Rabin's lectures.
A friend of mine was one of his graduate students and a teaching assistant for the class. He pointed out to me once that Professor Rabin would state many of his points during lecture twice. Once I started listening more carefully, I found this to be true. It was both subtle and pedagogically effective.
English was not his first language, but he enjoyed his struggles with it. I remember him stumbling over the pronunciation of a word during class. Giving up with a smile, he said, "This is a word I know only from books."
Amazing man, with many important contributions over a very long career. The Rabin Cryptosystem (like RSA, but with public exponent 2) is notable for two reasons. First, unlike RSA, it is provably as hard as "factorization" (as he would call it), and second, unlike RSA, it wasn't protected by patent.
Michael O. Rabin had important contributions in many domains, but from a practical point of view the most important are his contributions to cryptography.
After Ralph Merkle, Whitfield Diffie and Martin Hellman, Michael O. Rabin is the most important of the creators of public-key cryptography.
The RSA team (Ron Rivest, Adi Shamir and Leonard Adleman) is better known than Michael O. Rabin, but that is entirely due to marketing and advertising, because they founded a successful business.
In reality the RSA algorithm is superfluous and suboptimal. If the RSA team had never discovered this algorithm, that would have had a null impact on the practice of cryptography. Public-key cryptography would have been developed equally well, because the algorithms discovered by Merkle, Diffie, Hellman and Rabin are necessary and sufficient.
On the other hand, while without the publications of RSA, cryptography would have evolved pretty much in the same way, without the publications of Michael O. Rabin from the late seventies the development of public-key cryptography would have been delayed by some years, until someone else would have made the same discoveries.
Together with Ralph Merkle, Michael O. Rabin was the one who discovered the need for secure cryptographic hash functions, i.e. one-way hash functions, which are now critical for many applications, including digital signatures. Thus Rabin is the one who has shown how the previously proposed methods of digital signing must be used in practice. For example, the original signing algorithm proposed by RSA could trivially be broken and it became secure only in the modified form described by Rabin, i.e. with the use of a one-way hash function.
Originally, Merkle defined 2 conditions for one-way hash functions, of resistance to first preimage attacks and second preimage attacks, while Rabin defined 1 condition, of resistance to collision attacks. Soon after that it was realized that all 3 conditions are mandatory, so the 2 definitions, of Merkle and of Rabin, have been merged into the modern definition of such hash functions.
Unfortunately, both Merkle and Rabin have overlooked a 4th condition, of resistance to length extension attacks. This should have always been included in the definition of secure hash functions.
Because this 4th condition was omitted, the US Secure Hash Algorithm Standards defined algorithms that lack this property, which has forced many applications to use workarounds, like the HMAC algorithm, which for many years have wasted time and energy wherever encrypted communications were used, until more efficient authentication methods have been standardized, which do not use one-way hash functions, for instance GCM, which is today the most frequently used authentication algorithm on the Internet.
I think you're vastly underplaying the importance of RSA to cryptography. Personally it was the first time I was exposed to the concept of public key cryptography (in the 1980's). "would have been delayed by some years" is very dismissive. The same thing can be said of many inventions. Yet someone is/was the inventor.
RSA were the first to provide a practical and easy to understand implementation and that had a huge impact in practice.
That's not to downplay Rabin's or others contribution. That RSA pursued a certain commercial strategy that you may or may not like is not really relevant.
They didn't really found a successful business. They founded a middling business that didn't do much but license a patent until Security Dynamics, a smart card company, bought them and took over the name.
The story that I remember going around is that they each made some millions of dollars. That was a lot of money at the time for academics. I audited a cryptography course given by Adi Shamir in the early 90's and you couldn't tell he was rich though.
On the contrary, you cannot find frequently descriptions about the role of Michael O. Rabin in the creation of public-key cryptography, so few people are aware of it and I bet that no AI model can generate any text even remotely resembling this, because this information cannot be found in any single place in the possible training texts.
You can find definitions of secure hash functions everywhere, but pretty much nowhere you will find who are the authors of the conditions that are used in the modern definition and who have introduced the use of one-way hash functions.
I did not find this information anywhere, before reading the original publications of Rabin and Merkle from 1978/1979 and some later follow-up papers written by them.
You will not find this historical information in Wikipedia and I believe that it is important to know who are the true authors of the things that one uses daily. Connecting to this site or to any other site with https uses digital signatures that depend on the collision-resistant hash functions defined by Rabin and Merkle.
The Wikipedia article about Michael O. Rabin lists many of his achievements, but all those that are listed there are much less important than his contribution to the definition of the one-way hash functions, which lead to secure digital signatures.
Wikipedia mentions only the Rabin signature algorithm, but that has negligible importance, because it has been used only very rarely. On the other hand all other signature algorithms are based on the work of Rabin, by using secure hash functions.
I wouldn’t really call that AI slop. Some people just write longer posts because they’ve got a lot they want to get across, and you can usually tell it reflects their own opinions and what they think matters in the discussion. Actual AI-generated stuff tends to come off more generic and lacks that personal angle.
I don't think that is AI slop. adrian_b often post long posts because he thinks he has a lot to say, but you can often tell that they contain his personal views and points that he thinks are important related to the discussions whereas actual AI slop tends to be bland and generic.
Before AI and the swell of papers for money(tenure), not necessarily in that order, science mattered. As a result, the science mattered more in the past. RIP Rabin.
"As a young boy, he was very interested in mathematics and his father sent him to the best high school in Haifa, where he studied under mathematician Elisha Netanyahu, who was then a high school teacher."
Interesting. Some people are lucky enough to find their vocation quite early in life.
Sad that the only thing that shows up nowadays in searches tends to be Wikipedia. I miss the democratic internet with lots of quirky sites you could find with ease.
> Benzion Netanyahu ... A scholar of Judaic history, he was also an activist in the Revisionist Zionism movement, who lobbied in the United States to support the creation of the Jewish state.
Thank you! I’m a casual user of Wikipedia but after this thread I went through the history of edits on the article and...oh my.
I have a greater appreciation for folks like you and the other editors who seem to be constantly removing this type of stuf. Some truly horrendous slurs there.
The Wikipedia edit that this thread is discussing was as follows. I think it's worth printing it here to make the point that the commenter above you is completely right about the prevalence of anti-semitism in online discourse today:
> Michael Oser Rabin (Hebrew: מִיכָאֵל עוזר רַבִּין; September 1, 1931 – April 14, 2026) was a Jew (a.k.a. kike) rat computer scientist who was co-recipient, with Dana Scott, of the 1976 ACM Turing Award for their military research on efficiently culling goycattle in "Greater Israel".
Nothing about this edit is legitimate criticism of Israeli policy. It is pure anti-semitism. Rabin spent most of his career in the United States and worked in abstract mathematics.
I generally agree that legitimate criticism of Israel is often unfairly criticized as anti-semitic. I would like you to also acknowledge that many people on the left summarily dismiss blatant and rank anti-semitism, as you did here.
I commend you for the attempt, even if it’s clear that it’s falling on deaf ears to who you’re replying to.
The rest of us Jews appreciate that you didn’t let it slide.
It’s hard not to wonder why they even bothered clicking into this thread other than “oh the name sounds Jewish, I can push my narrative” especially with respect to their comment history.
That’s quite a take to assume willful blindness to widespread suffering.
What is pretty clear though: your obsession with constantly minimizing the lived experience of a minority with “no ackshually they deserve it because they really are this way” warrants a look in the mirror.
Who the heck sets it as their antisemitism campaign to edit “vile X” and “X (aka rat)” on Jewish biographies. Normalizing slurs? I thought the goal of antisemites was to spread propaganda about how Jews are bad. Writing “X (aka BAD)” seems like the weakest possible attempt at that.
I don’t know what people elsewhere in this thread are going on about Israel for.
I think racists, sexists, homophobes, transphobes, etc. who do that sort of thing aren’t doing it to convince anyone - it’s partially for shock value, partially to help normalize their attitudes and make other bigots feel more comfortable expressing their views, and partially to make the members of the group that they hate upset and feel unsafe.
One can oppose Israel and the virulent Jewish hate that has exploded in the last few years. It’s not as if massive violence against Jews has never happened.
I used to regularly donate to the wikimedia foundation every year. I stopped doing that as I find the whole project is now a political tool and cannot be relied on. Even ignoring vandalism like here, sometimtes the same articles get different meanings depending on the language you view them in.
Different language editions of Wikipedia are completely different projects, with distinct user bases. You're never looking at the "same" article across languages.
In that case, Wikipedia should not link to them (and even distance themselves from the edition) if they purposefully change the content of the article to suit a political agenda. The whole thing became a death match arena of factions as mature as 12 year old kids playing an actual death match arena game... This example here just demonstrates my point.
Wikipedia has demonstrably been ravaged by anti-semitism. Feel free to ignore any of the notes here about Israel / anti-Israeli sentiment which I understand is not clear cut. There's demonstrably antisemitic coalitions editing wikipedia en-masse.
This is a serious allegation that you've made before, but our records don’t show any instances where you raised a case of antisemitism and we refused or failed to act. The last time you emailed us pointing out an antisemitic comment (one that had already been flagged by several community members) we banned the account immediately and thanked you for reporting it.
In the case of this thread, the beginning of it happened when it was overnight for both dang and me, and as soon as either of us saw it we collapsed the off-topic subthread about antisemitism and flagged/killed any combative comments about that topic that hadn't already been flagged/killed by other community members. The claim we “leave this thread here alone, just as all the other stuff” is easily explained in this case, as in all cases: we were asleep or away from the computer when it was posted but dealt with it when we saw it.
The claim – or, irrefutable insinuation, as it so often is – that we allow more antisemitism to be posted here now than was allowed in the past is made just as often about anti-Islam sentiments and other forms of toxic ideology on either side of the spectrum. Maybe it’s true that dang and I are becoming more tolerant of antisemitism and anti-Islam sentiment and also right-wing and left-wing extremism all at once. Or maybe we should consider the possibility that discussion about politics and ideology, along with religions, particularly those pertaining to Israel and Palestine (and the broader Middle East), has become more incendiary and toxic everywhere in recent years, and it's seeped into almost all online and offline spaces, and we're no more able than King Canute to hold back that tide.
That doesn't mean we just blithely accept the “decline of HN”. We always hate to see any toxic comments posted about any topic. After all, this site is meant for curious discussions about stuff like programming languages and other things hackers find interesting. We didn't sign up to be a place where people come to rage about vexed geopolitical conflicts. When any toxic material is posted we want it flagged/killed and repeat guidelines-breaking users banned, just as has always been the case. Of course, there are things we should be doing, and are doing, to be better at detecting and addressing toxic content quickly. It takes time to develop and test these systems, and we're being challenged like never before by growth in the things that take up our time and attention, including new forms of abuse.
We are working hard, every day of every week, to manage these ever-changing issues and demands. You and everyone are always welcome to email us to point out any comment, submission or user that's in breach of the guidelines, and as you know, we will always reply, we'll often agree and take the action you're calling for, or if not, we'll thoroughly explain our reasoning. I can’t find a single instance where you’ve tried that approach with us and failed to get a response.
This is the page history. Using the K word for Jewish people is antisemitic. There was no mention of his affiliation of IDF, in fact the page mentions he was released from service in order to pursue his academics.
"@dang" doesn't do anything last I heard (though at this point it's used often enough that maybe the HN folks should consider it). If you want to reach the mods you can contact hn@ycombinator.com I believe.
Rabin Fingerprinting is one of my favorites of his contributions. It's a "rolling hash" that allows you to quickly compute a 32-bit (or larger) hash at *every* byte offset of a file. It is used most notably to do file block matching/deduplication when those matching blocks can be at any offset. It's tragically underappreciated.
I've been meaning to write up a tutorial as part of my Galois Field series. Someday..
Thank you again!
This replaced some O(n²) searches through ASCII text, reducing search time from dozens of seconds to fractions of a second.
0 - https://github.com/ttkb-oss/mipsmatch 1 - https://github.com/ttkb-oss/mipsmatch/wiki/Identifiers
I especially like how if you end up with hash characteristics that you don't like, your can just select a different irreducible Galois polynomial and now you've got a whole new hash algorithm. It's like tuning to a different frequency.
For me it means I don't have to worry about cases where there aren't enough nearby fingerprints for the annotation to adhere to, I can just add or remove polynomials until I get a good density.
I wrote a Rabin—Karp implementation in ~2006 as part of the spam and threat scanning stack for the MX Logic mail service. It was incredibly performant, letting us test {n} bytes against an essentially unlimited number of string signatures in O(n) time.
e.g., x minus x is zero, even for Euler, so therefore…
Found on Archive, https://web.archive.org/web/20210509160248/http://www.eecs.h...
Cryptography and Preventing Collusion in Second Price (Vickery) Auctions - Michael Rabin
https://www.youtube.com/watch?v=4cmCBVrVQqc
No chalkboard but more lectures
https://youtu.be/nbePExzSTQ0?si=KkTbwfwj5rMtQUhD&t=681 - פלאי תורת ההצפנות ויישומיה לתהליכים פיננסיים (The wonders of cryptography and financial applications)
https://www.youtube.com/watch?v=N_LG5Hcc8mM - Lecture 7 - Zero Knowledge Proofs and Applications Michael Rabin
For those interested in searching for more here's a Hebrew search string you can use: "פרופסור מיכאל רבין הרצאה" interesting enough Google and YT search yield results in English and Hebrew but possibly different ones than just searching in English.
EDIT: One more:
https://www.youtube.com/watch?v=30wkb46BE1k
A friend of mine was one of his graduate students and a teaching assistant for the class. He pointed out to me once that Professor Rabin would state many of his points during lecture twice. Once I started listening more carefully, I found this to be true. It was both subtle and pedagogically effective.
English was not his first language, but he enjoyed his struggles with it. I remember him stumbling over the pronunciation of a word during class. Giving up with a smile, he said, "This is a word I know only from books."
https://youtu.be/L3FZzGU3n14
After Ralph Merkle, Whitfield Diffie and Martin Hellman, Michael O. Rabin is the most important of the creators of public-key cryptography.
The RSA team (Ron Rivest, Adi Shamir and Leonard Adleman) is better known than Michael O. Rabin, but that is entirely due to marketing and advertising, because they founded a successful business.
In reality the RSA algorithm is superfluous and suboptimal. If the RSA team had never discovered this algorithm, that would have had a null impact on the practice of cryptography. Public-key cryptography would have been developed equally well, because the algorithms discovered by Merkle, Diffie, Hellman and Rabin are necessary and sufficient.
On the other hand, while without the publications of RSA, cryptography would have evolved pretty much in the same way, without the publications of Michael O. Rabin from the late seventies the development of public-key cryptography would have been delayed by some years, until someone else would have made the same discoveries.
Together with Ralph Merkle, Michael O. Rabin was the one who discovered the need for secure cryptographic hash functions, i.e. one-way hash functions, which are now critical for many applications, including digital signatures. Thus Rabin is the one who has shown how the previously proposed methods of digital signing must be used in practice. For example, the original signing algorithm proposed by RSA could trivially be broken and it became secure only in the modified form described by Rabin, i.e. with the use of a one-way hash function.
Originally, Merkle defined 2 conditions for one-way hash functions, of resistance to first preimage attacks and second preimage attacks, while Rabin defined 1 condition, of resistance to collision attacks. Soon after that it was realized that all 3 conditions are mandatory, so the 2 definitions, of Merkle and of Rabin, have been merged into the modern definition of such hash functions.
Unfortunately, both Merkle and Rabin have overlooked a 4th condition, of resistance to length extension attacks. This should have always been included in the definition of secure hash functions.
Because this 4th condition was omitted, the US Secure Hash Algorithm Standards defined algorithms that lack this property, which has forced many applications to use workarounds, like the HMAC algorithm, which for many years have wasted time and energy wherever encrypted communications were used, until more efficient authentication methods have been standardized, which do not use one-way hash functions, for instance GCM, which is today the most frequently used authentication algorithm on the Internet.
RSA were the first to provide a practical and easy to understand implementation and that had a huge impact in practice.
That's not to downplay Rabin's or others contribution. That RSA pursued a certain commercial strategy that you may or may not like is not really relevant.
He is a Turing Award winner.
On the contrary, you cannot find frequently descriptions about the role of Michael O. Rabin in the creation of public-key cryptography, so few people are aware of it and I bet that no AI model can generate any text even remotely resembling this, because this information cannot be found in any single place in the possible training texts.
You can find definitions of secure hash functions everywhere, but pretty much nowhere you will find who are the authors of the conditions that are used in the modern definition and who have introduced the use of one-way hash functions.
I did not find this information anywhere, before reading the original publications of Rabin and Merkle from 1978/1979 and some later follow-up papers written by them.
You will not find this historical information in Wikipedia and I believe that it is important to know who are the true authors of the things that one uses daily. Connecting to this site or to any other site with https uses digital signatures that depend on the collision-resistant hash functions defined by Rabin and Merkle.
The Wikipedia article about Michael O. Rabin lists many of his achievements, but all those that are listed there are much less important than his contribution to the definition of the one-way hash functions, which lead to secure digital signatures.
Wikipedia mentions only the Rabin signature algorithm, but that has negligible importance, because it has been used only very rarely. On the other hand all other signature algorithms are based on the work of Rabin, by using secure hash functions.
I really enjoyed reading it.
Interesting. Some people are lucky enough to find their vocation quite early in life.
Sad that the only thing that shows up nowadays in searches tends to be Wikipedia. I miss the democratic internet with lots of quirky sites you could find with ease.
Everything is intertwined at some level.
Interesting.
> Benzion Netanyahu ... A scholar of Judaic history, he was also an activist in the Revisionist Zionism movement, who lobbied in the United States to support the creation of the Jewish state.
I have a greater appreciation for folks like you and the other editors who seem to be constantly removing this type of stuf. Some truly horrendous slurs there.
> Michael Oser Rabin (Hebrew: מִיכָאֵל עוזר רַבִּין; September 1, 1931 – April 14, 2026) was a Jew (a.k.a. kike) rat computer scientist who was co-recipient, with Dana Scott, of the 1976 ACM Turing Award for their military research on efficiently culling goycattle in "Greater Israel".
Nothing about this edit is legitimate criticism of Israeli policy. It is pure anti-semitism. Rabin spent most of his career in the United States and worked in abstract mathematics.
I generally agree that legitimate criticism of Israel is often unfairly criticized as anti-semitic. I would like you to also acknowledge that many people on the left summarily dismiss blatant and rank anti-semitism, as you did here.
The rest of us Jews appreciate that you didn’t let it slide.
It’s hard not to wonder why they even bothered clicking into this thread other than “oh the name sounds Jewish, I can push my narrative” especially with respect to their comment history.
What is pretty clear though: your obsession with constantly minimizing the lived experience of a minority with “no ackshually they deserve it because they really are this way” warrants a look in the mirror.
I don’t know what people elsewhere in this thread are going on about Israel for.
I don’t believe for a second you’re a Jew.
https://www.adl.org/resources/report/editing-hate-how-anti-i...
In the case of this thread, the beginning of it happened when it was overnight for both dang and me, and as soon as either of us saw it we collapsed the off-topic subthread about antisemitism and flagged/killed any combative comments about that topic that hadn't already been flagged/killed by other community members. The claim we “leave this thread here alone, just as all the other stuff” is easily explained in this case, as in all cases: we were asleep or away from the computer when it was posted but dealt with it when we saw it.
The claim – or, irrefutable insinuation, as it so often is – that we allow more antisemitism to be posted here now than was allowed in the past is made just as often about anti-Islam sentiments and other forms of toxic ideology on either side of the spectrum. Maybe it’s true that dang and I are becoming more tolerant of antisemitism and anti-Islam sentiment and also right-wing and left-wing extremism all at once. Or maybe we should consider the possibility that discussion about politics and ideology, along with religions, particularly those pertaining to Israel and Palestine (and the broader Middle East), has become more incendiary and toxic everywhere in recent years, and it's seeped into almost all online and offline spaces, and we're no more able than King Canute to hold back that tide.
That doesn't mean we just blithely accept the “decline of HN”. We always hate to see any toxic comments posted about any topic. After all, this site is meant for curious discussions about stuff like programming languages and other things hackers find interesting. We didn't sign up to be a place where people come to rage about vexed geopolitical conflicts. When any toxic material is posted we want it flagged/killed and repeat guidelines-breaking users banned, just as has always been the case. Of course, there are things we should be doing, and are doing, to be better at detecting and addressing toxic content quickly. It takes time to develop and test these systems, and we're being challenged like never before by growth in the things that take up our time and attention, including new forms of abuse.
We are working hard, every day of every week, to manage these ever-changing issues and demands. You and everyone are always welcome to email us to point out any comment, submission or user that's in breach of the guidelines, and as you know, we will always reply, we'll often agree and take the action you're calling for, or if not, we'll thoroughly explain our reasoning. I can’t find a single instance where you’ve tried that approach with us and failed to get a response.
https://en.wikipedia.org/w/index.php?title=Michael_O._Rabin&...
It got reverted soon after and I suspect you kept missing the worst of it.
<https://blog.willmeye.rs/whos-received-a-black-bar/>