bluecrypt-keypairs.js/lib/rsa.js

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/*global Promise*/
(function (exports) {
'use strict';
var RSA = exports.Rasha = {};
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var x509 = exports.x509;
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if ('undefined' !== typeof module) { module.exports = RSA; }
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var PEM = exports.PEM;
var SSH = exports.SSH;
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var Enc = {};
var textEncoder = new TextEncoder();
RSA._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.";
RSA._universal = "Bluecrypt only supports crypto with standard cross-browser and cross-platform support.";
RSA.generate = function (opts) {
var wcOpts = {};
if (!opts) { opts = {}; }
if (!opts.kty) { opts.kty = 'RSA'; }
// Support PSS? I don't think it's used for Let's Encrypt
wcOpts.name = 'RSASSA-PKCS1-v1_5';
if (!opts.modulusLength) {
opts.modulusLength = 2048;
}
wcOpts.modulusLength = opts.modulusLength;
if (wcOpts.modulusLength >= 2048 && wcOpts.modulusLength < 3072) {
// erring on the small side... for no good reason
wcOpts.hash = { name: "SHA-256" };
} else if (wcOpts.modulusLength >= 3072 && wcOpts.modulusLength < 4096) {
wcOpts.hash = { name: "SHA-384" };
} else if (wcOpts.modulusLength < 4097) {
wcOpts.hash = { name: "SHA-512" };
} else {
// Public key thumbprints should be paired with a hash of similar length,
// so anything above SHA-512's keyspace would be left under-represented anyway.
return Promise.Reject(new Error("'" + wcOpts.modulusLength + "' is not within the safe and universally"
+ " acceptable range of 2048-4096. Typically you should pick 2048, 3072, or 4096, though other values"
+ " divisible by 8 are allowed. " + RSA._stance));
}
// TODO maybe allow this to be set to any of the standard values?
wcOpts.publicExponent = new Uint8Array([0x01, 0x00, 0x01]);
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: RSA.neuter({ jwk: privJwk })
};
});
});
};
// 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.
RSA.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 private parts
if (-1 !== ['d', 'p', 'q', 'dp', 'dq', 'qi'].indexOf(k)) { return; }
jwk[k] = JSON.parse(JSON.stringify(opts.jwk[k]));
});
return jwk;
};
// https://stackoverflow.com/questions/42588786/how-to-fingerprint-a-jwk
RSA.__thumbprint = function (jwk) {
// Use the same entropy for SHA as for key
var len = Math.floor(jwk.n.length * 0.75);
var alg = 'SHA-256';
// TODO this may be a bug
// need to confirm that the padding is no more or less than 1 byte
if (len >= 511) {
alg = 'SHA-512';
} else if (len >= 383) {
alg = 'SHA-384';
}
return window.crypto.subtle.digest(
{ name: alg }
, textEncoder.encode('{"e":"' + jwk.e + '","kty":"RSA","n":"' + jwk.n + '"}')
).then(function (hash) {
return Enc.bufToUrlBase64(new Uint8Array(hash));
});
};
RSA.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 RSA.import(opts).then(function (jwk) {
return RSA.__thumbprint(jwk);
});
}
return RSA.__thumbprint(jwk);
});
};
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RSA.export = function (opts) {
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return Promise.resolve().then(function () {
if (!opts || !opts.jwk || 'object' !== typeof opts.jwk) {
throw new Error("must pass { jwk: jwk }");
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}
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var jwk = JSON.parse(JSON.stringify(opts.jwk));
var format = opts.format;
var pub = opts.public;
if (pub || -1 !== [ 'spki', 'pkix', 'ssh', 'rfc4716' ].indexOf(format)) {
jwk = RSA.neuter({ jwk: jwk });
}
if ('RSA' !== jwk.kty) {
throw new Error("options.jwk.kty must be 'RSA' for RSA keys");
}
if (!jwk.p) {
// TODO test for n and e
pub = true;
if (!format || 'pkcs1' === format) {
format = 'pkcs1';
} else if (-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', 'pkcs1', or 'ssh' for public RSA keys, not ("
+ typeof format + ") " + format);
}
} else {
// TODO test for all necessary keys (d, p, q ...)
if (!format || 'pkcs1' === format) {
format = 'pkcs1';
} else if ('pkcs8' !== format) {
throw new Error("options.format must be 'pkcs1' or 'pkcs8' for private RSA keys");
}
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}
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if ('pkcs1' === format) {
if (jwk.d) {
return PEM.packBlock({ type: "RSA PRIVATE KEY", bytes: x509.packPkcs1(jwk) });
} else {
return PEM.packBlock({ type: "RSA PUBLIC KEY", bytes: x509.packPkcs1(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.pack({ jwk: jwk, comment: opts.comment });
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} else {
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throw new Error("Sanity Error: reached unreachable code block with format: " + format);
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}
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});
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};
RSA.pack = function (opts) {
// wrapped in a promise for API compatibility
// with the forthcoming browser version
// (and potential future native node capability)
return Promise.resolve().then(function () {
return RSA.export(opts);
});
};
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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));