Hash long string to short string. (s As String) As String Dim X As Long Dim crc As .
Hash long string to short string GetHashCode is indeed inappropriate for real hashing:. An integer has 32 bit positions and each position has two values. Again, what changes in the strings affect the placement, and which do not? Can you figure out how to pick strings that go to a particular slot in the table? Mar 23, 2012 · However, if you use a cryptographic hash you shorten the string to the length of hash. " Feb 21, 2015 · MD5 would be better described as a flawed cryptographic hash function, rather than a "non-cryptographic hash function". ascii_uppercase + string. hashCode() as: Implementation may vary across JVM versions. We would choose "kangaroo" because it is easily pronounceable. I'm looking for an algorithm that could calculate hash of such a strings and this hash will b May 30, 2024 · To create a unique hash from a specific string, it can be implemented using its own string-to-hash converting function. This means the total number of possible hash outputs is limited to 2^32, or about 4. The value returned by a hash function called hash digest, hash value, hash code, hash sum, checksum, or simply "hash. 23 % collision rate; SHA1. The drawback is that you are no longer able to reverse the hash back to the original string. Mar 11, 2017 · My understanding is that if I tell you that a given hash is the hash value of a single alpha-numeric character, then you can trivially identify what the source string is, by brute force checking the hashes. equals() involves Sep 26, 2024 · To shorten a long URL, we should implement a hash function that hashes a long URL to a 7- character string. randomUUID is a function that generates a string containing 36 characters long UUID. Is there a hash functi Aug 10, 2018 · However, being a 32-bit String hash function, String. In general if you have a hashtable that maps aKey The String Converter - Hash, Encode and Decode strings using any known technique. Uniqueness i Aug 24, 2011 · This still only works well for strings long enough (say at least 7-12 letters), but the original method would not work well for short strings either. Jan 13, 2017 · I need to generate a unique hash code for an object, based on its contents, e. Nov 23, 2024 · This method not only significantly reduces collisions compared to the simple hash function, but it also allows for diverse output streams by using a seed parameter. Apr 17, 2015 · Another solution that could be even better depending on your use-case is interned strings. digits) for _ in range(16)) print(x) Feb 21, 2018 · PostgreSQL has hash functions for many column types. Try out the sfold hash function. Oct 8, 2023 · The values returned by the function are called Hash Values or digests. in Lisp. Feb 6, 2013 · hash is a 8 characters long HEX string; hash can be expanded to 12/16/20 etc. Basically you have 16-bytes of data in the MD5 hash string. Concat(Convert. When you get a hash collision, the hash table falls back to using String. The most readable is shortuuid_random but is an external dependency and is slightly slower and has 6x the collisions. Dec 21, 2014 · This is too long for me. Create a row in the table for each URL you wish to track. This hash does not need to be secure in any way, just Oct 28, 2010 · Since Java 8 you can use. An important part of the security of a hashing algorithm is the algorithms collision resistance. Then shorten your 256 bit value to N bytes, where N is the number of characters you want in your string. Create a database table with two columns, ID (an integer) and URL (a string). [A-Z,a-z,0-9]. 62^16 = 4. They just won't fit. The complexity is O Jul 25, 2017 · String to be encrypted of variable size; the length of the resulting encrypted string; It does not need to be decrypted. If you still want a long hash: You can just take two standard [different!] hash functions for String->int, hash1() and hash2() and calculate: hash(s) = 2^32* hash1(s) + hash2(s) Aug 27, 2013 · My goal is to generate a short Hash string of 6 characters (possibly containing characters [A-Z][a-z][0-9]) for a string which is 42 case-insensitive alphanumeric characters in length. This will increase the chance of collisions, but not as bad as simply truncating the digest. There are many popular Hash Functions such as DJBX33A, MD5, and SHA-256. hash(string2); The small prime is in there to avoid equal hash code for switched values, i. Nov 11, 2018 · I've chosen "CityHash" to hash strings to 19 digit long integers (64bit integers), hoping this will lead to less potential collisions than Raymond's suggestion below Apr 17, 2022 · Has outputs of equal sizes, like hash functions; The outputs are short, e. Apr 23, 2019 · You could use an existing hash algorithm that produces something short, like MD5 (128 bits) or SHA1 (160). It will return the hash equivalent of a string. By applying the input difference on an MD5 input, you have a small but higher-than-random probability of finding the expected difference in the output. I've been looking at SHA384, but I've been unable to understand the samples online to the point of modifying it to make it hash to a specified length. By a low chance I mean that no two inputs have yet been found to equal the same hash in the history of the algorithm. What are some alternative hash functions that perhaps use every letter in the alphabet as well as integers that are perhaps shorter in string length and have low collision rates? Thanks! Jul 15, 2011 · As a side-note: obviously your += into a Long only works for short strings. Use a hash function to convert long string to short string. a URL with a short string with given length. Avoid creating duplicated short strings. 5000 characters) into a small number, e. When interacting with colleagues or StackExchange collaborators I routinely take the author at his word, assuming he tested (some of) the code and finds it suitable to merge to main. Because it has much more collisions than similar functions (FNV, Jenkins OAAT and MurmurOAAT) while having comparable throughput. The author also demonstrated that there are many odd, short String values that generate String. But it doesn't go backwards. there is almost no point in using the popular DJB2 hash function for strings on Intel x86-64 (or AArch64 for that matter) architecture. hash(string1) * 31 + MyHash. Mar 8, 2021 · None of those hash functions were designed to have this property. – Jim Mischel Commented Nov 14, 2016 at 21:35 On the other hand, Short strings will be stored in the string table strt in the global state because: strt is a hash table, which allows us to compare short strings efficiently with only their hash. Note that hashXXXextended functions take one extra parameter for seed and 0 means that no seed will be used. The function will be called over 100 million times. md5() seems to be kind of long (32-characters). A hash code is intended for efficient insertion and lookup in collections that are based on a hash table. However, it becomes difficult to manage it (in terms of using typing or displaying), and that's why the short version is used. No, actually the user asked how to generate a 6 character long hash string that can be used using JavaScript. If I generate an short id randomly then I would have to check every time if that shortid is available. Jan 15, 2015 · If you don't want a random string then you can certainly use a hash of the long string and truncate it to the length you want it to have, but there is no way around a database or storage. I would like to shorten that to 7-10 (or even shorter) characters long. Edit: some great suggestions/solutions here - thanks! A mini js lib to generate short, alpha-number, undecryptable and unique hash id from a long string (utf8 format). ToBase64String(hash). L=62) Calculate the base-L representation of N. UTF8. A mini js lib to generate short, alpha-number, undecryptable and unique hash id from a long string (utf8 format). How can I reduce it to a smaller dataset? Any suggestions on how to implement my own hashing algorithm? (One of the conditions was to not use existing algorithms). It's 32 Have you looked into comparing the data itself before calculating the strings? E. A String of length 9 has 72 bits. Also, a library named Crypto can be used to generate various types of hashes like SHA1, MD5, SHA256, and many more. However depending on the algorithm, there is a possibility to find a collision due to the mathematical theory behind these functions. Nov 10, 2019 · 2. 76724 e+28 keys: import random, string x = ''. The hash need not be unique. The hash code for String is lossy; many String values will result in the same hash code. I see your new comment about using the string in a URL. N = hash(o,R) You can use this number to produce a short string as follows: Choose a range of characters (alphabeth) to choose from e. If collisions exist, it is likely to get the original input string Jul 31, 2020 · Third 4 bytes = String. Sep 15, 2014 · It will probably almost never happen in your use case, but for the casual reader that happens to land here in search for javascript and hashing (like me), it could be worth noting that comparing two hash values is not the same as comparing two strings, hash may (and will) collide, that is . Where This is impossible. (MD5 tried to be cryptographically strong, and was used in that fashion for quite a while, but turned out to be broken. One Simple Solution could be Hashing. lodash' _. You'll notice there is no decode on an md5 object. I would like to get the shortest unambiguous SHA-1 hash string version of it. It just needs to change when input string changes. There are an infinity of strings with a given hash and beginning with a given substring. Re-encoding characters is generally done when the receiving system can't process them. A truly designed-to-be non-cryptographic hash function would be simpler and faster; more on that later. This gives us a string that’s 44 characters long. f4a4) in your sharable URLs (5) When receiving a Apr 11, 2023 · \$\begingroup\$ @pacmaninbw, Blindman67 helpfully raises a recurring issue that I would be happy to pursue in some Meta thread. hashCode(); short shorterHashCode = (short) (strHashCode % Short. Which method has less collisions, is faster and easier to read? TLDR. We strongly recommend that you click here and practice it, before moving on to the solution. ) Jul 23, 2010 · This is for the purpose of having a nice short URL which refers to an md5 hash in a database. hashCode(); Note that this solution creates a new Object for the stack, while the first doesn't (although it is likely that Java optimizes the object creation away. These text tags are unique because photos are never taken less than 1 second apart: 215MAIN-2014-05-02_13-24-52 152JBAR-2013-01-02_ May 4, 2011 · Here you can benchmark all supported hashes on your hardware, supported by your version of node. DateTime(2011,06,04) should equal DateTime(2011,06,04). Encode or decode strings to and from base64. Apr 18, 2012 · However, if you were able to change your criteria to allow for long hash outputs, then I would strongly suggest you look at SHA-512, as it will provide high quality outputs with an extremely low chance of duplication. Convert digest to hex string. The random_choice is the fastest, has fewer collisions but is IMO slightly harder to read. This is how symbols work e. An interned string is a string object whose value is the address of the actual string bytes. Warning. Some are cryptographic, and some is just for a checksum. – Dec 26, 2018 · That sums to 2^n - 1 strings, so by the piegonhole principle, either two strings have the same compressed form (uh-oh — this is the same idea as a hash collision) — or some compressed form is longer than the original, which can happen easily in Huffman encoding when storing the map if your original string is short and made of a lot of . May 23, 2017 · If you only have the hash as information, you cannot talk about "the long string": There are an infinity of strings with a given hash.
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