bluecrypt-keypairs.js/lib/ecdsa.js

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2019-04-18 07:56:32 +00:00
/*global Promise*/
(function (exports) {
'use strict';
var EC = exports.Eckles = {};
if ('undefined' !== typeof module) { module.exports = EC; }
var Enc = {};
var textEncoder = new TextEncoder();
EC._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.";
EC._universal = "Bluecrypt only supports crypto with standard cross-browser and cross-platform support.";
EC.generate = function (opts) {
var wcOpts = {};
if (!opts) { opts = {}; }
if (!opts.kty) { opts.kty = 'EC'; }
// ECDSA has only the P curves and an associated bitlength
wcOpts.name = 'ECDSA';
if (!opts.namedCurve) {
opts.namedCurve = 'P-256';
}
wcOpts.namedCurve = opts.namedCurve; // true for supported curves
if (/256/.test(wcOpts.namedCurve)) {
wcOpts.namedCurve = 'P-256';
wcOpts.hash = { name: "SHA-256" };
} else if (/384/.test(wcOpts.namedCurve)) {
wcOpts.namedCurve = 'P-384';
wcOpts.hash = { name: "SHA-384" };
} else {
return Promise.Reject(new Error("'" + wcOpts.namedCurve + "' is not an NIST approved ECDSA namedCurve. "
+ " Please choose either 'P-256' or 'P-384'. "
+ EC._stance));
}
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var extractable = true;
return window.crypto.subtle.generateKey(
wcOpts
, extractable
, [ 'sign', 'verify' ]
).then(function (result) {
return window.crypto.subtle.exportKey(
"jwk"
, result.privateKey
).then(function (privJwk) {
return {
private: privJwk
, public: EC.neuter({ jwk: privJwk })
};
});
});
};
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EC.export = function (opts) {
if (!opts || !opts.jwk || 'object' !== typeof opts.jwk) {
throw new Error("must pass { jwk: jwk } as a JSON object");
}
var jwk = JSON.parse(JSON.stringify(opts.jwk));
var format = opts.format;
if (opts.public || -1 !== [ 'spki', 'pkix', 'ssh', 'rfc4716' ].indexOf(format)) {
jwk.d = null;
}
if ('EC' !== jwk.kty) {
throw new Error("options.jwk.kty must be 'EC' for EC keys");
}
if (!jwk.d) {
if (!format || -1 !== [ 'spki', 'pkix' ].indexOf(format)) {
format = 'spki';
} else if (-1 !== [ 'ssh', 'rfc4716' ].indexOf(format)) {
format = 'ssh';
} else {
throw new Error("options.format must be 'spki' or 'ssh' for public EC keys, not ("
+ typeof format + ") " + format);
}
} else {
if (!format || 'sec1' === format) {
format = 'sec1';
} else if ('pkcs8' !== format) {
throw new Error("options.format must be 'sec1' or 'pkcs8' for private EC keys, not '" + format + "'");
}
}
if (-1 === [ 'P-256', 'P-384' ].indexOf(jwk.crv)) {
throw new Error("options.jwk.crv must be either P-256 or P-384 for EC keys, not '" + jwk.crv + "'");
}
if (!jwk.y) {
throw new Error("options.jwk.y must be a urlsafe base64-encoded either P-256 or P-384");
}
if ('sec1' === format) {
return PEM.packBlock({ type: "EC PRIVATE KEY", bytes: x509.packSec1(jwk) });
} else if ('pkcs8' === format) {
return PEM.packBlock({ type: "PRIVATE KEY", bytes: x509.packPkcs8(jwk) });
} else if (-1 !== [ 'spki', 'pkix' ].indexOf(format)) {
return PEM.packBlock({ type: "PUBLIC KEY", bytes: x509.packSpki(jwk) });
} else if (-1 !== [ 'ssh', 'rfc4716' ].indexOf(format)) {
return SSH.packSsh(jwk);
} else {
throw new Error("Sanity Error: reached unreachable code block with format: " + format);
}
};
EC.pack = function (opts) {
return Promise.resolve().then(function () {
return EC.exportSync(opts);
});
};
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// 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.
EC.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 EC private parts
if ('d' === k) { return; }
jwk[k] = JSON.parse(JSON.stringify(opts.jwk[k]));
});
return jwk;
};
// https://stackoverflow.com/questions/42588786/how-to-fingerprint-a-jwk
EC.__thumbprint = function (jwk) {
// Use the same entropy for SHA as for key
var alg = 'SHA-256';
if (/384/.test(jwk.crv)) {
alg = 'SHA-384';
}
return window.crypto.subtle.digest(
{ name: alg }
, textEncoder.encode('{"crv":"' + jwk.crv + '","kty":"EC","x":"' + jwk.x + '","y":"' + jwk.y + '"}')
).then(function (hash) {
return Enc.bufToUrlBase64(new Uint8Array(hash));
});
};
EC.thumbprint = function (opts) {
return Promise.resolve().then(function () {
var jwk;
if ('EC' === opts.kty) {
jwk = opts;
} else if (opts.jwk) {
jwk = opts.jwk;
} else {
return EC.import(opts).then(function (jwk) {
return EC.__thumbprint(jwk);
});
}
return EC.__thumbprint(jwk);
});
};
Enc.bufToUrlBase64 = function (u8) {
return Enc.bufToBase64(u8)
.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
};
Enc.bufToBase64 = function (u8) {
var bin = '';
u8.forEach(function (i) {
bin += String.fromCharCode(i);
});
return btoa(bin);
};
}('undefined' !== typeof module ? module.exports : window));