Hashids
A small .NET package to generate YouTube-like IDs from numbers.
It converts numbers like 347
into strings like yr8
, or array of numbers like [27, 986]
into 3kTMd
. You can also decode those ids back. This is useful in bundling several parameters into one, hiding actual IDs, or simply using them as short string IDs.
Features
- Creates short unique ids from integers. (only positive numbers & zero)
- Generates non-sequential IDs for incremental input to stay unguessable.
- Supports single number or array of numbers. (supports
int
andlong
) - Allows custom alphabet as well as salt — so ids are unique only to you. (salt must be smaller than alphabet)
- Allows specifying minimum hash length.
- Tries to avoid basic English curse words.
NOTE: This is NOT a true cryptographic hash, since it is reversible
Installation
Install the package with NuGet
Install-Package hashids.net
Usage
Import namespace
using HashidsNet;
Encoding one number
You can pass a unique salt value so your hashes differ from everyone else's. I use "this is my salt" as an example.
var hashids = new Hashids("this is my salt");
var hash = hashids.Encode(12345);
hash
is now going to be:
NkK9
If your id is stored as a Int64
you need to use "EncodeLong".
var hashids = new Hashids("this is my salt");
var hash = hashids.EncodeLong(666555444333222L);
hash
is now going to be:
KVO9yy1oO5j
Decoding
Notice during decoding, same salt value is used:
var hashids = new Hashids("this is my salt");
numbers = hashids.Decode("NkK9");
numbers
is now going to be:
[ 12345 ]
var hashids = new Hashids("this is my salt");
numbers = hashids.DecodeLong("KVO9yy1oO5j");
numbers
is now going to be:
[ 666555444333222L ]
Decoding with different salt
Decoding will not work if salt is changed:
var hashids = new Hashids("this is my pepper");
numbers = hashids.Decode("NkK9");
numbers
is now going to be:
[]
Encoding several numbers
var hashids = new Hashids("this is my salt");
var hash = hashids.Encode(683, 94108, 123, 5);
hash
is now going to be:
aBMswoO2UB3Sj
Decoding is done the same way
var hashids = new Hashids("this is my salt");
var numbers = hashids.Decode("aBMswoO2UB3Sj")
numbers
is now going to be:
[ 683, 94108, 123, 5 ]
Encoding and specifying minimum hash length
Here we encode integer 1, and set the minimum hash length to 8 (by default it's 0 -- meaning hashes will be the shortest possible length).
var hashids = new Hashids("this is my salt", 8);
var hash = hashids.Encode(1);
hash
is now going to be:
gB0NV05e
Decoding
var hashids = new Hashids("this is my salt", 8);
var numbers = hashids.Decode("gB0NV05e");
numbers
is now going to be:
[ 1 ]
Specifying custom hash alphabet
Here we set the alphabet to consist of: "abcdefghijkABCDEFGHIJK12345"
var hashids = new Hashids("this is my salt", 0, "abcdefghijkABCDEFGHIJK12345")
var hash = hashids.Encode(1, 2, 3, 4, 5)
hash
is now going to be:
Ec4iEHeF3
Randomness
The primary purpose of hashids is to obfuscate ids. It's not meant or tested to be used for security purposes or compression. Having said that, this algorithm does try to make these hashes unguessable and unpredictable:
Repeating numbers
var hashids = new Hashids("this is my salt");
var hash = hashids.Encode(5, 5, 5, 5);
You don't see any repeating patterns that might show there's 4 identical numbers in the hash:
1Wc8cwcE
Same with incremented numbers:
var hashids = new Hashids("this is my salt");
var hash = hashids.Encode(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
hash
will be :
kRHnurhptKcjIDTWC3sx
Incrementing number hashes:
var hashids = new Hashids("this is my salt");
hashids.Encode(1); // => NV
hashids.Encode(2); // => 6m
hashids.Encode(3); // => yD
hashids.Encode(4); // => 2l
hashids.Encode(5); // => rD
Encoding using a HEX string
var hashids = new Hashids("this is my salt");
var hash = hashids.EncodeHex("DEADBEEF");
hash
is now going to be:
kRNrpKlJ
Decoding to a HEX string
var hashids = new Hashids("this is my salt");
var hex = hashids.DecodeHex("kRNrpKlJ");
hex
is now going to be:
DEADBEEF
Changelog
1.4.0
- Modernized project with updated build targets now set to
netnet461
,net5.0
,netstandard2.0
- Accepted PR #30 Fix floating-point math to handle large ratio of alphabet to separators.
- Accepted PR #37 Performance and memory optimizations.
- Accepted PR #42 Performance updates and added BenchmarkDotnet for profiling.
- Accepted PR #43 Improved performance and reduced allocations.
- Fixed issues #23, #32, #35 Fix floating-point math, now replaced by Horner's method.
- Fixed issue #27 Allow dashes in alphabet (dashes caused issues with Regex which is not used anymore).
- Fixed issue #21 Fix encoding exception when decoding a character used as guard.
- Fixed issue #29 Added tests to confirm thread-safety.
1.3.0
- Accepted PR #26 - We now support .netstandard2.0. Thanks @MatthewKing
1.2.2
- Accepted PR #19 - We now only instantiate the HEX-connected Regexes if we use any of the HEX functions. This will speed up creation of "Hashids"-instances. It is likely that most users doesn't use the HEX-functions.
1.2.1
- Accepted PR #11
- Fixed issue #15 Decoding strings that contain characters not in the alphabet will now return empty array. (To conform to behaviour in the js-library).
- Fixed issue #18 Encoding with a negative number will now return empty string. (To conform to behaviour in the js-library).
1.2.0
- .NET Core support. Sorry for the wait and thanks haroldma, mlafleur and lstyles for submitting pull requests.
1.1.2
- Fixed issue #14 that caused HEX values to be encoded/decoded incorrectly.
1.1.1
- Accepted PR #12 that fixed an issue when encoding very many longs at the same time
1.1.0
- Added support for
long
via new functions to not introduce breaking changes.EncodeLong
for encodes.DecodeLong
for decodes.
- Added interface
IHashids
for people who want an interface to work with.
1.0.1
- The .NET 4.0 version of the package used .NET 4.5 as build target. This was fixed and a new version was pushed to nuget.
1.0.0
-
Several public functions marked obsolete and renamed versions added, to be more appropriate:
- Function
Encrypt()
changed toEncode()
- Function
Decrypt()
changed toDecode()
- Function
EncryptHex()
changed toEncodeHex()
- Function
DecryptHex()
changed toDecodeHex()
Hashids was designed to encode integers, primary ids at most. We've had several requests to encrypt sensitive data with Hashids and this is the wrong algorithm for that. So to encourage more appropriate use,
encrypt/decrypt
is being "downgraded" toencode/decode
. - Function
0.3.4
- The public functions are now virtual and therefor can be mocked with a mocking library.
0.3.3
- Rewrote the code to support the new hashing algorithm.
- Support for
EncryptHex
andDecryptHex
0.1.4
- Initial version of the port.