> For the complete documentation index, see [llms.txt](https://bryan-guner.gitbook.io/my-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bryan-guner.gitbook.io/my-docs/redux/repos/examples/real-world/node_modules/asn1.md).

# asn1

node-asn1 is a library for encoding and decoding ASN.1 datatypes in pure JS. Currently BER encoding is supported; at some point I'll likely have to do DER.

### Usage

Mostly, if you're *actually* needing to read and write ASN.1, you probably don't need this readme to explain what and why. If you have no idea what ASN.1 is, see this: ftp\://ftp.rsa.com/pub/pkcs/ascii/layman.asc

The source is pretty much self-explanatory, and has read/write methods for the common types out there.

#### Decoding

The following reads an ASN.1 sequence with a boolean.

```
var Ber = require('asn1').Ber;

var reader = new Ber.Reader(Buffer.from([0x30, 0x03, 0x01, 0x01, 0xff]));

reader.readSequence();
console.log('Sequence len: ' + reader.length);
if (reader.peek() === Ber.Boolean)
  console.log(reader.readBoolean());
```

#### Encoding

The following generates the same payload as above.

```
var Ber = require('asn1').Ber;

var writer = new Ber.Writer();

writer.startSequence();
writer.writeBoolean(true);
writer.endSequence();

console.log(writer.buffer);
```

### Installation

```
npm install asn1
```

### License

MIT.

### Bugs

See <https://github.com/joyent/node-asn1/issues>.