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sshpk
=========
Parse, convert, fingerprint and use SSH keys (both public and private) in pure
node -- no `ssh-keygen` or other external dependencies.
Supports RSA, DSA, ECDSA (nistp-\*) and ED25519 key types, in PEM (PKCS#1,
PKCS#8) and OpenSSH formats.
This library has been extracted from
[`node-http-signature`](https://github.com/joyent/node-http-signature)
(work by [Mark Cavage](https://github.com/mcavage) and
[Dave Eddy](https://github.com/bahamas10)) and
[`node-ssh-fingerprint`](https://github.com/bahamas10/node-ssh-fingerprint)
(work by Dave Eddy), with additions (including ECDSA support) by
[Alex Wilson](https://github.com/arekinath).
Install
-------
```
npm install sshpk
```
Examples
--------
```js
var sshpk = require('sshpk');
var fs = require('fs');
/* Read in an OpenSSH-format public key */
var keyPub = fs.readFileSync('id_rsa.pub');
var key = sshpk.parseKey(keyPub, 'ssh');
/* Get metadata about the key */
console.log('type => %s', key.type);
console.log('size => %d bits', key.size);
console.log('comment => %s', key.comment);
/* Compute key fingerprints, in new OpenSSH (>6.7) format, and old MD5 */
console.log('fingerprint => %s', key.fingerprint().toString());
console.log('old-style fingerprint => %s', key.fingerprint('md5').toString());
```
Example output:
```
type => rsa
size => 2048 bits
comment => foo@foo.com
fingerprint => SHA256:PYC9kPVC6J873CSIbfp0LwYeczP/W4ffObNCuDJ1u5w
old-style fingerprint => a0:c8:ad:6c:32:9a:32:fa:59:cc:a9:8c:0a:0d:6e:bd
```
More examples: converting between formats:
```js
/* Read in a PEM public key */
var keyPem = fs.readFileSync('id_rsa.pem');
var key = sshpk.parseKey(keyPem, 'pem');
/* Convert to PEM PKCS#8 public key format */
var pemBuf = key.toBuffer('pkcs8');
/* Convert to SSH public key format (and return as a string) */
var sshKey = key.toString('ssh');
```
Signing and verifying:
```js
/* Read in an OpenSSH/PEM *private* key */
var keyPriv = fs.readFileSync('id_ecdsa');
var key = sshpk.parsePrivateKey(keyPriv, 'pem');
var data = 'some data';
/* Sign some data with the key */
var s = key.createSign('sha1');
s.update(data);
var signature = s.sign();
/* Now load the public key (could also use just key.toPublic()) */
var keyPub = fs.readFileSync('id_ecdsa.pub');
key = sshpk.parseKey(keyPub, 'ssh');
/* Make a crypto.Verifier with this key */
var v = key.createVerify('sha1');
v.update(data);
var valid = v.verify(signature);
/* => true! */
```
Matching fingerprints with keys:
```js
var fp = sshpk.parseFingerprint('SHA256:PYC9kPVC6J873CSIbfp0LwYeczP/W4ffObNCuDJ1u5w');
var keys = [sshpk.parseKey(...), sshpk.parseKey(...), ...];
keys.forEach(function (key) {
if (fp.matches(key))
console.log('found it!');
});
```
Usage
-----
## Public keys
### `parseKey(data[, format = 'auto'[, name]])`
Parses a key from a given data format and returns a new `Key` object.
Parameters
- `data` -- Either a Buffer or String, containing the key
- `format` -- String name of format to use, valid options are:
- `auto`: choose automatically from all below
- `pem`: supports both PKCS#1 and PKCS#8
- `ssh`: standard OpenSSH format,
- `pkcs1`, `pkcs8`: variants of `pem`
- `rfc4253`: raw OpenSSH wire format
- `openssh`: new post-OpenSSH 6.5 internal format, produced by
`ssh-keygen -o`
- `name` -- Optional name for the key being parsed (eg. the filename that
was opened). Used to generate Error messages
### `Key.isKey(obj)`
Returns `true` if the given object is a valid `Key` object created by a version
of `sshpk` compatible with this one.
Parameters
- `obj` -- Object to identify
### `Key#type`
String, the type of key. Valid options are `rsa`, `dsa`, `ecdsa`.
### `Key#size`
Integer, "size" of the key in bits. For RSA/DSA this is the size of the modulus;
for ECDSA this is the bit size of the curve in use.
### `Key#comment`
Optional string, a key comment used by some formats (eg the `ssh` format).
### `Key#curve`
Only present if `this.type === 'ecdsa'`, string containing the name of the
named curve used with this key. Possible values include `nistp256`, `nistp384`
and `nistp521`.
### `Key#toBuffer([format = 'ssh'])`
Convert the key into a given data format and return the serialized key as
a Buffer.
Parameters
- `format` -- String name of format to use, for valid options see `parseKey()`
### `Key#toString([format = 'ssh])`
Same as `this.toBuffer(format).toString()`.
### `Key#fingerprint([algorithm = 'sha256'])`
Creates a new `Fingerprint` object representing this Key's fingerprint.
Parameters
- `algorithm` -- String name of hash algorithm to use, valid options are `md5`,
`sha1`, `sha256`, `sha384`, `sha512`
### `Key#createVerify([hashAlgorithm])`
Creates a `crypto.Verifier` specialized to use this Key (and the correct public
key algorithm to match it). The returned Verifier has the same API as a regular
one, except that the `verify()` function takes only the target signature as an
argument.
Parameters
- `hashAlgorithm` -- optional String name of hash algorithm to use, any
supported by OpenSSL are valid, usually including
`sha1`, `sha256`.
`v.verify(signature[, format])` Parameters
- `signature` -- either a Signature object, or a Buffer or String
- `format` -- optional String, name of format to interpret given String with.
Not valid if `signature` is a Signature or Buffer.
### `Key#createDiffieHellman()`
### `Key#createDH()`
Creates a Diffie-Hellman key exchange object initialized with this key and all
necessary parameters. This has the same API as a `crypto.DiffieHellman`
instance, except that functions take `Key` and `PrivateKey` objects as
arguments, and return them where indicated for.
This is only valid for keys belonging to a cryptosystem that supports DHE
or a close analogue (i.e. `dsa`, `ecdsa` and `curve25519` keys). An attempt
to call this function on other keys will yield an `Error`.
## Private keys
### `parsePrivateKey(data[, format = 'auto'[, name]])`
Parses a private key from a given data format and returns a new
`PrivateKey` object.
Parameters
- `data` -- Either a Buffer or String, containing the key
- `format` -- String name of format to use, valid options are:
- `auto`: choose automatically from all below
- `pem`: supports both PKCS#1 and PKCS#8
- `ssh`, `openssh`: new post-OpenSSH 6.5 internal format, produced by
`ssh-keygen -o`
- `pkcs1`, `pkcs8`: variants of `pem`
- `rfc4253`: raw OpenSSH wire format
- `name` -- Optional name for the key being parsed (eg. the filename that
was opened). Used to generate Error messages
### `PrivateKey.isPrivateKey(obj)`
Returns `true` if the given object is a valid `PrivateKey` object created by a
version of `sshpk` compatible with this one.
Parameters
- `obj` -- Object to identify
### `PrivateKey#type`
String, the type of key. Valid options are `rsa`, `dsa`, `ecdsa`.
### `PrivateKey#size`
Integer, "size" of the key in bits. For RSA/DSA this is the size of the modulus;
for ECDSA this is the bit size of the curve in use.
### `PrivateKey#curve`
Only present if `this.type === 'ecdsa'`, string containing the name of the
named curve used with this key. Possible values include `nistp256`, `nistp384`
and `nistp521`.
### `PrivateKey#toBuffer([format = 'pkcs1'])`
Convert the key into a given data format and return the serialized key as
a Buffer.
Parameters
- `format` -- String name of format to use, valid options are listed under
`parsePrivateKey`. Note that ED25519 keys default to `openssh`
format instead (as they have no `pkcs1` representation).
### `PrivateKey#toString([format = 'pkcs1'])`
Same as `this.toBuffer(format).toString()`.
### `PrivateKey#toPublic()`
Extract just the public part of this private key, and return it as a `Key`
object.
### `PrivateKey#fingerprint([algorithm = 'sha256'])`
Same as `this.toPublic().fingerprint()`.
### `PrivateKey#createVerify([hashAlgorithm])`
Same as `this.toPublic().createVerify()`.
### `PrivateKey#createSign([hashAlgorithm])`
Creates a `crypto.Sign` specialized to use this PrivateKey (and the correct
key algorithm to match it). The returned Signer has the same API as a regular
one, except that the `sign()` function takes no arguments, and returns a
`Signature` object.
Parameters
- `hashAlgorithm` -- optional String name of hash algorithm to use, any
supported by OpenSSL are valid, usually including
`sha1`, `sha256`.
`v.sign()` Parameters
- none
### `PrivateKey#derive(newType)`
Derives a related key of type `newType` from this key. Currently this is
only supported to change between `ed25519` and `curve25519` keys which are
stored with the same private key (but usually distinct public keys in order
to avoid degenerate keys that lead to a weak Diffie-Hellman exchange).
Parameters
- `newType` -- String, type of key to derive, either `ed25519` or `curve25519`
## Fingerprints
### `parseFingerprint(fingerprint[, algorithms])`
Pre-parses a fingerprint, creating a `Fingerprint` object that can be used to
quickly locate a key by using the `Fingerprint#matches` function.
Parameters
- `fingerprint` -- String, the fingerprint value, in any supported format
- `algorithms` -- Optional list of strings, names of hash algorithms to limit
support to. If `fingerprint` uses a hash algorithm not on
this list, throws `InvalidAlgorithmError`.
### `Fingerprint.isFingerprint(obj)`
Returns `true` if the given object is a valid `Fingerprint` object created by a
version of `sshpk` compatible with this one.
Parameters
- `obj` -- Object to identify
### `Fingerprint#toString([format])`
Returns a fingerprint as a string, in the given format.
Parameters
- `format` -- Optional String, format to use, valid options are `hex` and
`base64`. If this `Fingerprint` uses the `md5` algorithm, the
default format is `hex`. Otherwise, the default is `base64`.
### `Fingerprint#matches(key)`
Verifies whether or not this `Fingerprint` matches a given `Key`. This function
uses double-hashing to avoid leaking timing information. Returns a boolean.
Parameters
- `key` -- a `Key` object, the key to match this fingerprint against
## Signatures
### `parseSignature(signature, algorithm, format)`
Parses a signature in a given format, creating a `Signature` object. Useful
for converting between the SSH and ASN.1 (PKCS/OpenSSL) signature formats, and
also returned as output from `PrivateKey#createSign().sign()`.
A Signature object can also be passed to a verifier produced by
`Key#createVerify()` and it will automatically be converted internally into the
correct format for verification.
Parameters
- `signature` -- a Buffer (binary) or String (base64), data of the actual
signature in the given format
- `algorithm` -- a String, name of the algorithm to be used, possible values
are `rsa`, `dsa`, `ecdsa`
- `format` -- a String, either `asn1` or `ssh`
### `Signature.isSignature(obj)`
Returns `true` if the given object is a valid `Signature` object created by a
version of `sshpk` compatible with this one.
Parameters
- `obj` -- Object to identify
### `Signature#toBuffer([format = 'asn1'])`
Converts a Signature to the given format and returns it as a Buffer.
Parameters
- `format` -- a String, either `asn1` or `ssh`
### `Signature#toString([format = 'asn1'])`
Same as `this.toBuffer(format).toString('base64')`.
Errors
------
### `InvalidAlgorithmError`
The specified algorithm is not valid, either because it is not supported, or
because it was not included on a list of allowed algorithms.
Thrown by `Fingerprint.parse`, `Key#fingerprint`.
Properties
- `algorithm` -- the algorithm that could not be validated
### `FingerprintFormatError`
The fingerprint string given could not be parsed as a supported fingerprint
format, or the specified fingerprint format is invalid.
Thrown by `Fingerprint.parse`, `Fingerprint#toString`.
Properties
- `fingerprint` -- if caused by a fingerprint, the string value given
- `format` -- if caused by an invalid format specification, the string value given
### `KeyParseError`
The key data given could not be parsed as a valid key.
Properties
- `keyName` -- `name` that was given to `Key#parse`
- `format` -- the `format` that was trying to parse the key
- `innerErr` -- the inner Error thrown by the format parser
Friends of sshpk
----------------
* [`sshpk-agent`](https://github.com/arekinath/node-sshpk-agent) is a library
for speaking the `ssh-agent` protocol from node.js, which uses `sshpk`
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