README
¶
C4 ID - Universally Unique and Consistent Identification
import "github.com/Avalanche-io/c4"
This is a Go package that implements the C4 ID system SMPTE standard ST 2114:2017. C4 IDs are universally unique and consistent identifiers that standardize the derivation and formatting of data identification so that all users independently agree on the identification of any block or set of blocks of data.
C4 IDs are 90 character long strings suitable for use in filenames, URLs, database fields, or anywhere else that a string identifier might normally be used. In ram C4 IDs are represented in a 64 byte "digest" format.
Features
- A single C4 id can represent multiple files.
- C4 ids are unique, random, and unforgeable.
- C4 ids are identical for the same file in different locations or points in time.
- A network connection is not required to generate C4 ids.
- A C4 id can be used in filenames, URLs, json and xml.
- C4 ids can be selected easily with double click (a problem for many unique identifiers).
- Easily discover C4 ids in arbitrary text with a simple regex
c4[1-9A-HJ-NP-Za-km-z]{88} - Naming files by their C4 id automatically deduplicates them.
Comparison of Encodings
C4 is the shortest self identifying SHA-512 encoding and is the only standardized encoding. To illustrate, the following is the SHA-512 of "foo" in hex, base64 and c4 encodings:
# encoding length id
hex 135: sha512-f7fbba6e0636f890e56fbbf3283e524c6fa3204ae298382d624741d0dc6638326e282c41be5e4254d8820772c5518a2c5a8c0c7f7eda19594a7eb539453e1ed7
base64 95: sha512-9/u6bgY2+JDlb7vzKD5STG+jIErimDgtYkdB0NxmODJuKCxBvl5CVNiCB3LFUYosWowMf37aGVlKfrU5RT4e1w==
c4 90: c43inc2qGhSWQUMRvDMW6GAjJnRFY5sxq399wcUcWLTuPai84A2QWTfYu1gAW8f5FmZFGeYpLsSPyrSUh9Ao3J68Cc
Example Usage
package main
import (
"fmt"
"strings"
"github.com/Avalanche-io/c4"
)
func main() {
// Generate a C4 ID for any contiguous block of data...
id := c4.Identify(strings.NewReader("alfa"))
fmt.Println(id)
// output: c43zYcLni5LF9rR4Lg4B8h3Jp8SBwjcnyyeh4bc6gTPHndKuKdjUWx1kJPYhZxYt3zV6tQXpDs2shPsPYjgG81wZM1
// Generate a C4 ID for any number of non-contiguous blocks...
var ids c4.IDs
var inputs = []string{"alfa", "bravo", "charlie", "delta", "echo", "foxtrot", "golf", "hotel", "india"}
for _, input := range inputs {
ids = append(ids, c4.Identify(strings.NewReader(input)))
}
fmt.Println(ids.ID())
// output: c435RzTWWsjWD1Fi7dxS3idJ7vFgPVR96oE95RfDDT5ue7hRSPENePDjPDJdnV46g7emDzWK8LzJUjGESMG5qzuXqq
}
Releases
Current release: v0.8.0
Links
Videos:
Contributing
Contributions are welcome. The following are some general guidelines for project organization. If you have questions please open an issue.
The master branch holds the current release, and older releases can be found by their version number. The dev branch represents the development branch from which bug and feature branches should be taken. Pull requests that are accepted will be merged against the dev branch and then pushed to versioned releases as appropriate.
Feature and bug branches should follow the github integrated naming convention. Features should be given the new tag, and bugs the bug tag. Here is an example of checking out a feature branch:
> git checkout dev
Switched to branch 'dev'
Your branch is up-to-date with 'origin/dev'.
> git checkout -b new/#99_some_github_issue
...
If a branch for an issue is already listed in this repository, then check it out and work from it.
License
This software is released under the MIT license. See LICENSE for more information.
Documentation
¶
Overview ¶
This package implements the C4 ID system **SMPTE standard ST 2114:2017**. C4 IDs are a universally unique and consistent identifiers standardize the derivation and formatting of data identification so that all users independently agree on the identification of any given block or set of blocks of data.
C4 IDs are 90 character long strings suitable for use in filenames, URLs, database fields, or anywhere else that a string identifier might normally be used.
In ram C4 IDs are represented in a 64 byte "digest" format.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ID ¶
type ID [64]byte
// Encoder generates an ID for a contiguous bock of data.
type Encoder struct {
err error
h hash.Hash
}
// NewIDEncoder makes a new Encoder.
func NewEncoder() *Encoder {
return &Encoder{
h: sha512.New(),
}
}
// Write writes bytes to the hash that makes up the ID.
func (e *Encoder) Write(b []byte) (int, error) {
return e.h.Write(b)
}
// ID returns the ID for the bytes written so far.
func (e *Encoder) ID() (id ID) {
copy(id[:], e.h.Sum(nil))
return id
}
// Reset the encoder so it can identify a new block of data.
func (e *Encoder) Reset() {
e.h.Reset()
}
ID represents a C4 ID.
func (ID) Cmp ¶
Cmp compares two IDs. There are 3 possible return values.
-1 : Argument id is less than calling id.
0 : Argument id and calling id are identical.
+1 : Argument id is greater than calling id.
Comparison is done on the actual numerical value of the ids. Not the string representation.
func (ID) MarshalJSON ¶
func (*ID) UnmarshalJSON ¶
type Identifiable ¶
type Identifiable interface {
ID() ID
}
Identifiable is an interface that requires an ID() method that returns the c4 ID of the of the object.
type Tree ¶
type Tree []byte
`Tree` implements an ID tree as used for calculating IDs of non-contiguous sets of data. A C4 ID Tree is a type of merkle tree except that the list of IDs is sorted. According to the standard this is done to insure that two identical lists of IDs always resolve to the same ID.
func NewTree ¶
NewTree creates a new Tree from a DigestSlice, and copies the digests into the tree. However, it does not compute the tree.
Source Files
Directories