bluecrypt-keypairs.js/lib/keypairs.js

285 lines
9.5 KiB
JavaScript

/*global Promise*/
(function (exports) {
'use strict';
var Keypairs = exports.Keypairs = {};
var Rasha = exports.Rasha || require('rasha');
var Eckles = exports.Eckles || require('eckles');
var Enc = exports.Enc || {};
Keypairs._stance = "We take the stance that if you're knowledgeable enough to"
+ " properly and securely use non-standard crypto then you shouldn't need Bluecrypt anyway.";
Keypairs._universal = "Bluecrypt only supports crypto with standard cross-browser and cross-platform support.";
Keypairs.generate = function (opts) {
opts = opts || {};
var p;
if (!opts.kty) { opts.kty = opts.type; }
if (!opts.kty) { opts.kty = 'EC'; }
if (/^EC/i.test(opts.kty)) {
p = Eckles.generate(opts);
} else if (/^RSA$/i.test(opts.kty)) {
p = Rasha.generate(opts);
} else {
return Promise.Reject(new Error("'" + opts.kty + "' is not a well-supported key type."
+ Keypairs._universal
+ " Please choose 'EC', or 'RSA' if you have good reason to."));
}
return p.then(function (pair) {
return Keypairs.thumbprint({ jwk: pair.public }).then(function (thumb) {
pair.private.kid = thumb; // maybe not the same id on the private key?
pair.public.kid = thumb;
return pair;
});
});
};
// Chopping off the private parts is now part of the public API.
// I thought it sounded a little too crude at first, but it really is the best name in every possible way.
Keypairs.neuter = Keypairs._neuter = function (opts) {
// trying to find the best balance of an immutable copy with custom attributes
var jwk = {};
Object.keys(opts.jwk).forEach(function (k) {
if ('undefined' === typeof opts.jwk[k]) { return; }
// ignore RSA and EC private parts
if (-1 !== ['d', 'p', 'q', 'dp', 'dq', 'qi'].indexOf(k)) { return; }
jwk[k] = JSON.parse(JSON.stringify(opts.jwk[k]));
});
return jwk;
};
Keypairs.thumbprint = function (opts) {
return Promise.resolve().then(function () {
if (/EC/i.test(opts.jwk.kty)) {
return Eckles.thumbprint(opts);
} else {
return Rasha.thumbprint(opts);
}
});
};
Keypairs.publish = function (opts) {
if ('object' !== typeof opts.jwk || !opts.jwk.kty) { throw new Error("invalid jwk: " + JSON.stringify(opts.jwk)); }
// returns a copy
var jwk = Keypairs.neuter(opts);
if (jwk.exp) {
jwk.exp = setTime(jwk.exp);
} else {
if (opts.exp) { jwk.exp = setTime(opts.exp); }
else if (opts.expiresIn) { jwk.exp = Math.round(Date.now()/1000) + opts.expiresIn; }
else if (opts.expiresAt) { jwk.exp = opts.expiresAt; }
}
if (!jwk.use && false !== jwk.use) { jwk.use = "sig"; }
if (jwk.kid) { return Promise.resolve(jwk); }
return Keypairs.thumbprint({ jwk: jwk }).then(function (thumb) { jwk.kid = thumb; return jwk; });
};
// JWT a.k.a. JWS with Claims using Compact Serialization
Keypairs.signJwt = function (opts) {
return Keypairs.thumbprint({ jwk: opts.jwk }).then(function (thumb) {
var header = opts.header || {};
var claims = JSON.parse(JSON.stringify(opts.claims || {}));
header.typ = 'JWT';
if (!header.kid) { header.kid = thumb; }
if (!header.alg && opts.alg) { header.alg = opts.alg; }
if (!claims.iat && (false === claims.iat || false === opts.iat)) {
claims.iat = undefined;
} else if (!claims.iat) {
claims.iat = Math.round(Date.now()/1000);
}
if (opts.exp) {
claims.exp = setTime(opts.exp);
} else if (!claims.exp && (false === claims.exp || false === opts.exp)) {
claims.exp = undefined;
} else if (!claims.exp) {
throw new Error("opts.claims.exp should be the expiration date as seconds, human form (i.e. '1h' or '15m') or false");
}
if (opts.iss) { claims.iss = opts.iss; }
if (!claims.iss && (false === claims.iss || false === opts.iss)) {
claims.iss = undefined;
} else if (!claims.iss) {
throw new Error("opts.claims.iss should be in the form of https://example.com/, a secure OIDC base url");
}
return Keypairs.signJws({
jwk: opts.jwk
, pem: opts.pem
, protected: header
, header: undefined
, payload: claims
}).then(function (jws) {
return [ jws.protected, jws.payload, jws.signature ].join('.');
});
});
};
Keypairs.signJws = function (opts) {
return Keypairs.thumbprint(opts).then(function (thumb) {
function alg() {
if (!opts.jwk) {
throw new Error("opts.jwk must exist and must declare 'typ'");
}
return ('RSA' === opts.jwk.kty) ? "RS256" : "ES256";
}
function sign(pem) {
var header = opts.header;
var protect = opts.protected;
var payload = opts.payload;
// Compute JWS signature
var protectedHeader = "";
// Because unprotected headers are allowed, regrettably...
// https://stackoverflow.com/a/46288694
if (false !== protect) {
if (!protect) { protect = {}; }
if (!protect.alg) { protect.alg = alg(); }
// There's a particular request where Let's Encrypt explicitly doesn't use a kid
if (!protect.kid && false !== protect.kid) { protect.kid = thumb; }
protectedHeader = JSON.stringify(protect);
}
// Not sure how to handle the empty case since ACME POST-as-GET must be empty
//if (!payload) {
// throw new Error("opts.payload should be JSON, string, or ArrayBuffer (it may be empty, but that must be explicit)");
//}
// Trying to detect if it's a plain object (not Buffer, ArrayBuffer, Array, Uint8Array, etc)
if (payload && ('string' !== typeof payload)
&& ('undefined' === typeof payload.byteLength)
&& ('undefined' === typeof payload.byteLength)
) {
payload = JSON.stringify(payload);
}
// Converting to a buffer, even if it was just converted to a string
if ('string' === typeof payload) {
payload = Enc.binToBuf(payload);
}
// node specifies RSA-SHAxxx even when it's actually ecdsa (it's all encoded x509 shasums anyway)
var nodeAlg = "SHA" + (((protect||header).alg||'').replace(/^[^\d]+/, '')||'256');
var protected64 = Enc.strToUrlBase64(protectedHeader);
var payload64 = Enc.bufToUrlBase64(payload);
var binsig = require('crypto')
.createSign(nodeAlg)
.update(protect ? (protected64 + "." + payload64) : payload64)
.sign(pem)
;
if ('EC' === opts.jwk.kty) {
// ECDSA JWT signatures differ from "normal" ECDSA signatures
// https://tools.ietf.org/html/rfc7518#section-3.4
binsig = convertIfEcdsa(binsig);
}
var sig = binsig.toString('base64')
.replace(/\+/g, '-')
.replace(/\//g, '_')
.replace(/=/g, '')
;
return {
header: header
, protected: protected64 || undefined
, payload: payload64
, signature: sig
};
}
function convertIfEcdsa(binsig) {
// should have asn1 sequence header of 0x30
if (0x30 !== binsig[0]) { throw new Error("Impossible EC SHA head marker"); }
var index = 2; // first ecdsa "R" header byte
var len = binsig[1];
var lenlen = 0;
// Seek length of length if length is greater than 127 (i.e. two 512-bit / 64-byte R and S values)
if (0x80 & len) {
lenlen = len - 0x80; // should be exactly 1
len = binsig[2]; // should be <= 130 (two 64-bit SHA-512s, plus padding)
index += lenlen;
}
// should be of BigInt type
if (0x02 !== binsig[index]) { throw new Error("Impossible EC SHA R marker"); }
index += 1;
var rlen = binsig[index];
var bits = 32;
if (rlen > 49) {
bits = 64;
} else if (rlen > 33) {
bits = 48;
}
var r = binsig.slice(index + 1, index + 1 + rlen).toString('hex');
var slen = binsig[index + 1 + rlen + 1]; // skip header and read length
var s = binsig.slice(index + 1 + rlen + 1 + 1).toString('hex');
if (2 *slen !== s.length) { throw new Error("Impossible EC SHA S length"); }
// There may be one byte of padding on either
while (r.length < 2*bits) { r = '00' + r; }
while (s.length < 2*bits) { s = '00' + s; }
if (2*(bits+1) === r.length) { r = r.slice(2); }
if (2*(bits+1) === s.length) { s = s.slice(2); }
return Enc.hexToBuf(r + s);
}
if (opts.pem && opts.jwk) {
return sign(opts.pem);
} else {
return Keypairs.export({ jwk: opts.jwk }).then(sign);
}
});
};
function setTime(time) {
if ('number' === typeof time) { return time; }
var t = time.match(/^(\-?\d+)([dhms])$/i);
if (!t || !t[0]) {
throw new Error("'" + time + "' should be datetime in seconds or human-readable format (i.e. 3d, 1h, 15m, 30s");
}
var now = Math.round(Date.now()/1000);
var num = parseInt(t[1], 10);
var unit = t[2];
var mult = 1;
switch(unit) {
// fancy fallthrough, what fun!
case 'd':
mult *= 24;
/*falls through*/
case 'h':
mult *= 60;
/*falls through*/
case 'm':
mult *= 60;
/*falls through*/
case 's':
mult *= 1;
}
return now + (mult * num);
}
Enc.hexToBuf = function (hex) {
var arr = [];
hex.match(/.{2}/g).forEach(function (h) {
arr.push(parseInt(h, 16));
});
return 'undefined' !== typeof Uint8Array ? new Uint8Array(arr) : arr;
};
Enc.strToUrlBase64 = function (str) {
return Enc.bufToUrlBase64(Enc.binToBuf(str));
};
Enc.binToBuf = function (bin) {
var arr = bin.split('').map(function (ch) {
return ch.charCodeAt(0);
});
return 'undefined' !== typeof Uint8Array ? new Uint8Array(arr) : arr;
};
}('undefined' !== typeof module ? module.exports : window));