107 lines
3.2 KiB
Markdown
107 lines
3.2 KiB
Markdown
# Bluecrypt ASN.1 Parser
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An ASN.1 decoder in less than 100 lines of Vanilla JavaScript,
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part of the Bluecrypt suite.
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<br>
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<small>(< 150 with newlines and comments)</small>
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# Features
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| <100 lines of code | 1.1k gzipped | 2.5k minified | 4.7k with comments |
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* [x] Complete ASN.1 parser
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* [x] Parses x.509 certificates
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* [x] PEM (base64-encoded DER)
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* [x] VanillaJS, Zero Dependencies
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* [x] Browsers (even old ones)
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* [x] Online [Demo](https://coolaj86.com/demos/asn1-parser/)
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* [ ] Node.js (built, publishing soon)
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### Need an ASN.1 Builder too?
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Check out https://git.coolaj86.com/coolaj86/asn1-packer.js/
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# Demo
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<https://coolaj86.com/demos/asn1-parser/>
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<img border="1" src="https://i.imgur.com/gV7w7bM.png" />
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# Usage
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```html
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<script src="https://git.coolaj86.com/coolaj86/asn1-parser.js/raw/branch/master/asn1-parser.js"></script>
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```
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```js
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'use strict';
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var ASN1 = window.ASN1 // 62 lines
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var Enc = window.Enc // 27 lines
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var PEM = window.PEM // 6 lines
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var pem = [ '-----BEGIN EC PRIVATE KEY-----'
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+ 'MHcCAQEEIImMnaNu2jRjvQwVFnhhDw/KDYtS2Q6n8T5kJYniwY1UoAoGCCqGSM49'
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+ 'AwEHoUQDQgAEIT1SWLxsacPiE5Z16jkopAn8/+85rMjgyCokrnjDft6Y/YnA4A50'
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+ 'yZe7CnFsqeDcpnPbubP6cpYiVcnevNIYyg=='
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+ '-----END EC PRIVATE KEY-----'
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].join('\n');
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var der = PEM.parseBlock(pem).der;
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var json = ASN1.parse(der);
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console.log(json);
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```
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```js
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{ "type": 48 /*0x30*/, "lengthSize": 0, "length": 89
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, "children": [
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{ "type": 48 /*0x30*/, "lengthSize": 0, "length": 19
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, "children": [
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{ "type": 6, "lengthSize": 0, "length": 7, "value": "<0x2a8648ce3d0201>" },
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{ "type": 6, "lengthSize": 0, "length": 8, "value": "<0x2a8648ce3d030107>" }
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]
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},
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{ "type": 3, "lengthSize": 0, "length": 66,
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"value": "<0x04213d5258bc6c69c3e2139675ea3928a409fcffef39acc8e0c82a24ae78c37ede98fd89c0e00e74c997bb0a716ca9e0dca673dbb9b3fa72962255c9debcd218ca>"
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}
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]
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}
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```
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Note: `value` will be a `Uint8Array`, not a hex string.
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### Optimistic Parsing
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This is a dumbed-down, minimal ASN1 parser
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(though quite clever in its simplicity).
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There are some ASN.1 types (at least Bit String and Octet String,
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possibly others) that can be treated either as primitive values or
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as container types base on the schema being used.
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Rather than incorporating knowledge of each possible x509 schema,
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this parser will return values for types that are _always_ values,
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it recurse on types that are _always_ containers and, for ambigiuous
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types, it will first try to recurse and, on error, will fall back to
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returning a value.
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In theory, it is possible that it will produce false positives,
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but that would be highly unlikely in real-world scenarios
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(PEM, x509, PKCS#1, SEC1, PKCS#8, SPKI, PKIX, CSR, etc).
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I'd be interested to hear if you encounter such a case.
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### Zero Dependencies
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> A little copying is better than a little dependency - Golang Proverbs by Rob Pike
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Rather than requiring hundreds (or thousands) of lines of dependencies,
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this library takes the approach of including from other libraries in its suite
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to produce a small, focused file that does exactly what it needs to do.
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# Legal
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[Bluecrypt VanillaJS ASN.1 Parser](https://git.coolaj86.com/coolaj86/asn1-parser.js) |
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MPL-2.0
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