💯 ECDSA tools. Key Generation. PEM-to-JWK. JWK-to-PEM. Lightweight. Zero Dependencies. Universal compatibility.
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'use strict';
var ASN1;
var EC = module.exports;
var Hex = {};
var PEM = {};
// 1.2.840.10045.3.1.7
// prime256v1 (ANSI X9.62 named elliptic curve)
var OBJ_ID_EC = '06 08 2A8648CE3D030107'.replace(/\s+/g, '').toLowerCase();
// 1.3.132.0.34
// secp384r1 (SECG (Certicom) named elliptic curve)
var OBJ_ID_EC_384 = '06 05 2B81040022'.replace(/\s+/g, '').toLowerCase();
// 1.2.840.10045.2.1
// ecPublicKey (ANSI X9.62 public key type)
var OBJ_ID_EC_PUB = '06 07 2A8648CE3D0201'.replace(/\s+/g, '').toLowerCase();
// 19 e c d s a - s h a 2 - n i s t p 2 5 6
var SSH_EC_P256 = '00000013 65 63 64 73 61 2d 73 68 61 32 2d 6e 69 73 74 70 32 35 36'
.replace(/\s+/g, '').toLowerCase();
// 19 e c d s a - s h a 2 - n i s t p 3 8 4
var SSH_EC_P384 = '00000013 65 63 64 73 61 2d 73 68 61 32 2d 6e 69 73 74 70 33 38 34'
.replace(/\s+/g, '').toLowerCase();
// The one good thing that came from the b***kchain hysteria: good EC documentation
// https://davidederosa.com/basic-blockchain-programming/elliptic-curve-keys/
PEM._toUrlSafeBase64 = function (u8) {
//console.log('Len:', u8.byteLength);
return Buffer.from(u8).toString('base64')
.replace(/\+/g, '-').replace(/\//g, '_').replace(/=/g, '');
};
PEM.parseBlock = function pemToDer(pem) {
var typ;
var pub;
var crv;
var der = Buffer.from(pem.split(/\n/).filter(function (line, i) {
if (0 === i) {
if (/ PUBLIC /.test(line)) {
pub = true;
} else if (/ PRIVATE /.test(line)) {
pub = false;
}
if (/ EC/.test(line)) {
typ = 'EC';
}
}
return !/---/.test(line);
}).join(''), 'base64');
if (!typ || 'EC' === typ) {
var hex = toHex(der);
if (-1 !== hex.indexOf(OBJ_ID_EC)) {
typ = 'EC';
crv = 'P-256';
} else if (-1 !== hex.indexOf(OBJ_ID_EC_384)) {
typ = 'EC';
crv = 'P-384';
} else {
// TODO support P-384 as well (but probably nothing else)
console.warn("unsupported ec curve");
}
}
return { kty: typ, pub: pub, der: der, crv: crv };
};
PEM.packBlock = function (opts) {
// TODO allow for headers?
return '-----BEGIN ' + opts.type + '-----\n'
+ toBase64(opts.bytes).match(/.{1,64}/g).join('\n') + '\n'
+ '-----END ' + opts.type + '-----'
;
};
function toHex(ab) {
var hex = [];
var u8 = new Uint8Array(ab);
var size = u8.byteLength;
var i;
var h;
for (i = 0; i < size; i += 1) {
h = u8[i].toString(16);
if (2 === h.length) {
hex.push(h);
} else {
hex.push('0' + h);
}
}
return hex.join('').replace(/\s+/g, '').toLowerCase();
}
Hex.fromAB = toHex;
Hex.fromInt = function numToHex(d) {
d = d.toString(16);
if (d.length % 2) {
return '0' + d;
}
return d;
};
Hex.toUint8 = function (hex) {
var buf = Buffer.from(hex, 'hex');
var ab = buf.buffer;
return new Uint8Array(ab.slice(buf.offset, buf.offset + buf.byteLength));
};
function toBase64(u8) {
return Buffer.from(u8).toString('base64');
}
function urlBase64ToBase64(ub64) {
var r = ub64 % 4;
if (2 === r) {
ub64 += '==';
} else if (3 === r) {
ub64 += '=';
}
return ub64.replace(/-/g, '+').replace(/_/g, '/');
}
function base64ToUint8(b64) {
var buf = Buffer.from(b64, 'base64');
return new Uint8Array(buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength));
}
EC.parseSec1 = function parseEcOnlyPrivkey(u8, jwk) {
var index = 7;
var len = 32;
var olen = OBJ_ID_EC.length/2;
if ("P-384" === jwk.crv) {
olen = OBJ_ID_EC_384.length/2;
index = 8;
len = 48;
}
if (len !== u8[index - 1]) {
throw new Error("Unexpected bitlength " + len);
}
// private part is d
var d = u8.slice(index, index + len);
// compression bit index
var ci = index + len + 2 + olen + 2 + 3;
var c = u8[ci];
var x, y;
if (0x04 === c) {
y = u8.slice(ci + 1 + len, ci + 1 + len + len);
} else if (0x02 !== c) {
throw new Error("not a supported EC private key");
}
x = u8.slice(ci + 1, ci + 1 + len);
return {
kty: jwk.kty
, crv: jwk.crv
, d: PEM._toUrlSafeBase64(d)
//, dh: toHex(d)
, x: PEM._toUrlSafeBase64(x)
//, xh: toHex(x)
, y: PEM._toUrlSafeBase64(y)
//, yh: toHex(y)
};
};
EC.parsePkcs8 = function parseEcPkcs8(u8, jwk) {
var index = 24 + (OBJ_ID_EC.length/2);
var len = 32;
if ("P-384" === jwk.crv) {
index = 24 + (OBJ_ID_EC_384.length/2) + 2;
len = 48;
}
//console.log(index, u8.slice(index));
if (0x04 !== u8[index]) {
//console.log(jwk);
throw new Error("privkey not found");
}
var d = u8.slice(index+2, index+2+len);
var ci = index+2+len+5;
var xi = ci+1;
var x = u8.slice(xi, xi + len);
var yi = xi+len;
var y;
if (0x04 === u8[ci]) {
y = u8.slice(yi, yi + len);
} else if (0x02 !== u8[ci]) {
throw new Error("invalid compression bit (expected 0x04 or 0x02)");
}
return {
kty: jwk.kty
, crv: jwk.crv
, d: PEM._toUrlSafeBase64(d)
//, dh: toHex(d)
, x: PEM._toUrlSafeBase64(x)
//, xh: toHex(x)
, y: PEM._toUrlSafeBase64(y)
//, yh: toHex(y)
};
};
EC.parseSpki = function parsePem(u8, jwk) {
var ci = 16 + OBJ_ID_EC.length/2;
var len = 32;
if ("P-384" === jwk.crv) {
ci = 16 + OBJ_ID_EC_384.length/2;
len = 48;
}
var c = u8[ci];
var xi = ci + 1;
var x = u8.slice(xi, xi + len);
var yi = xi + len;
var y;
if (0x04 === c) {
y = u8.slice(yi, yi + len);
} else if (0x02 !== c) {
throw new Error("not a supported EC private key");
}
return {
kty: jwk.kty
, crv: jwk.crv
, x: PEM._toUrlSafeBase64(x)
//, xh: toHex(x)
, y: PEM._toUrlSafeBase64(y)
//, yh: toHex(y)
};
};
EC.parsePkix = EC.parseSpki;
EC.parseSsh = function (pem) {
var jwk = { kty: 'EC', crv: null, x: null, y: null };
var b64 = pem.split(/\s+/g)[1];
var buf = Buffer.from(b64, 'base64');
var hex = buf.toString('hex');
var index = 40;
var len;
if (0 === hex.indexOf(SSH_EC_P256)) {
jwk.crv = 'P-256';
len = 32;
} else if (0 === hex.indexOf(SSH_EC_P384)) {
jwk.crv = 'P-384';
len = 48;
}
var x = buf.slice(index, index + len);
var y = buf.slice(index + len, index + len + len);
jwk.x = PEM._toUrlSafeBase64(x);
jwk.y = PEM._toUrlSafeBase64(y);
return jwk;
};
/*global Promise*/
EC.parse = function parseEc(opts) {
return Promise.resolve().then(function () {
if (!opts || !opts.pem || 'string' !== typeof opts.pem) {
throw new Error("must pass { pem: pem } as a string");
}
if (0 === opts.pem.indexOf('ecdsa-sha2-')) {
return EC.parseSsh(opts.pem);
}
var pem = opts.pem;
var u8 = PEM.parseBlock(pem).der;
var hex = toHex(u8);
var jwk = { kty: 'EC', crv: null, x: null, y: null };
//console.log();
if (-1 !== hex.indexOf(OBJ_ID_EC)) {
jwk.crv = "P-256";
// PKCS8
if (0x02 === u8[3] && 0x30 === u8[6] && 0x06 === u8[8]) {
//console.log("PKCS8", u8[3].toString(16), u8[6].toString(16), u8[8].toString(16));
jwk = EC.parsePkcs8(u8, jwk);
// EC-only
} else if (0x02 === u8[2] && 0x04 === u8[5] && 0xA0 === u8[39]) {
//console.log("EC---", u8[2].toString(16), u8[5].toString(16), u8[39].toString(16));
jwk = EC.parseSec1(u8, jwk);
// SPKI/PKIK (Public)
} else if (0x30 === u8[2] && 0x06 === u8[4] && 0x06 === u8[13]) {
//console.log("SPKI-", u8[2].toString(16), u8[4].toString(16), u8[13].toString(16));
jwk = EC.parseSpki(u8, jwk);
// Error
} else {
//console.log("PKCS8", u8[3].toString(16), u8[6].toString(16), u8[8].toString(16));
//console.log("EC---", u8[2].toString(16), u8[5].toString(16), u8[39].toString(16));
//console.log("SPKI-", u8[2].toString(16), u8[4].toString(16), u8[13].toString(16));
throw new Error("unrecognized key format");
}
} else if (-1 !== hex.indexOf(OBJ_ID_EC_384)) {
jwk.crv = "P-384";
// PKCS8
if (0x02 === u8[3] && 0x30 === u8[6] && 0x06 === u8[8]) {
//console.log("PKCS8", u8[3].toString(16), u8[6].toString(16), u8[8].toString(16));
jwk = EC.parsePkcs8(u8, jwk);
// EC-only
} else if (0x02 === u8[3] && 0x04 === u8[6] && 0xA0 === u8[56]) {
//console.log("EC---", u8[3].toString(16), u8[6].toString(16), u8[56].toString(16));
jwk = EC.parseSec1(u8, jwk);
// SPKI/PKIK (Public)
} else if (0x30 === u8[2] && 0x06 === u8[4] && 0x06 === u8[13]) {
//console.log("SPKI-", u8[2].toString(16), u8[4].toString(16), u8[13].toString(16));
jwk = EC.parseSpki(u8, jwk);
// Error
} else {
//console.log("PKCS8", u8[3].toString(16), u8[6].toString(16), u8[8].toString(16));
//console.log("EC---", u8[3].toString(16), u8[6].toString(16), u8[56].toString(16));
//console.log("SPKI-", u8[2].toString(16), u8[4].toString(16), u8[13].toString(16));
throw new Error("unrecognized key format");
}
} else {
throw new Error("Supported key types are P-256 and P-384");
}
if (opts.public) {
if (true !== opts.public) {
throw new Error("options.public must be either `true` or `false` not ("
+ typeof opts.public + ") '" + opts.public + "'");
}
delete jwk.d;
}
return jwk;
});
};
EC.toJwk = EC.import = EC.parse;
EC.pack = function (opts) {
return Promise.resolve().then(function () {
if (!opts || !opts.jwk || 'object' !== typeof opts.jwk) {
throw new Error("must pass { jwk: jwk }");
}
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");
}
}
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");
}
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: EC.packSec1(jwk) });
} else if ('pkcs8' === format) {
return PEM.packBlock({ type: "PRIVATE KEY", bytes: EC.packPkcs8(jwk) });
} else if (-1 !== [ 'spki', 'pkix' ].indexOf(format)) {
return PEM.packBlock({ type: "PUBLIC KEY", bytes: EC.packSpki(jwk) });
} else if (-1 !== [ 'ssh', 'rfc4716' ].indexOf(format)) {
return EC.packSsh(jwk);
} else {
throw new Error("Sanity Error: reached unreachable code block with format: " + format);
}
});
};
EC.packSec1 = function (jwk) {
var d = toHex(base64ToUint8(urlBase64ToBase64(jwk.d)));
var x = toHex(base64ToUint8(urlBase64ToBase64(jwk.x)));
var y = toHex(base64ToUint8(urlBase64ToBase64(jwk.y)));
var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
return Hex.toUint8(
ASN1('30'
, ASN1.UInt('01')
, ASN1('04', d)
, ASN1('A0', objId)
, ASN1('A1', ASN1.BitStr('04' + x + y)))
);
};
EC.packPkcs8 = function (jwk) {
var d = toHex(base64ToUint8(urlBase64ToBase64(jwk.d)));
var x = toHex(base64ToUint8(urlBase64ToBase64(jwk.x)));
var y = toHex(base64ToUint8(urlBase64ToBase64(jwk.y)));
var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
return Hex.toUint8(
ASN1('30'
, ASN1.UInt('00')
, ASN1('30'
, OBJ_ID_EC_PUB
, objId
)
, ASN1('04'
, ASN1('30'
, ASN1.UInt('01')
, ASN1('04', d)
, ASN1('A1', ASN1.BitStr('04' + x + y)))))
);
};
EC.packSpki = function (jwk) {
var x = toHex(base64ToUint8(urlBase64ToBase64(jwk.x)));
var y = toHex(base64ToUint8(urlBase64ToBase64(jwk.y)));
var objId = ('P-256' === jwk.crv) ? OBJ_ID_EC : OBJ_ID_EC_384;
return Hex.toUint8(
ASN1('30'
, ASN1('30'
, OBJ_ID_EC_PUB
, objId
)
, ASN1.BitStr('04' + x + y))
);
};
EC.packPkix = EC.packSpki;
EC.packSsh = function (jwk) {
// Custom SSH format
var typ = 'ecdsa-sha2-nistp256';
var a = '32 35 36';
var b = '41';
var comment = jwk.crv + '@localhost';
if ('P-256' !== jwk.crv) {
typ = 'ecdsa-sha2-nistp384';
a = '33 38 34';
b = '61';
}
var x = toHex(base64ToUint8(urlBase64ToBase64(jwk.x)));
var y = toHex(base64ToUint8(urlBase64ToBase64(jwk.y)));
var ssh = Hex.toUint8(
('00 00 00 13 65 63 64 73 61 2d 73 68 61 32 2d 6e 69 73 74 70'
+ a + '00 00 00 08 6e 69 73 74 70' + a + '00 00 00' + b
+ '04' + x + y).replace(/\s+/g, '').toLowerCase()
);
return typ + ' ' + toBase64(ssh) + ' ' + comment;
};
//
// A dumbed-down, minimal ASN.1 packer
//
// Almost every ASN.1 type that's important for CSR
// can be represented generically with only a few rules.
ASN1 = function ASN1(/*type, hexstrings...*/) {
var args = Array.prototype.slice.call(arguments);
var typ = args.shift();
var str = args.join('').replace(/\s+/g, '').toLowerCase();
var len = (str.length/2);
var lenlen = 0;
var hex = typ;
// We can't have an odd number of hex chars
if (len !== Math.round(len)) {
throw new Error("invalid hex");
}
// The first byte of any ASN.1 sequence is the type (Sequence, Integer, etc)
// The second byte is either the size of the value, or the size of its size
// 1. If the second byte is < 0x80 (128) it is considered the size
// 2. If it is > 0x80 then it describes the number of bytes of the size
// ex: 0x82 means the next 2 bytes describe the size of the value
// 3. The special case of exactly 0x80 is "indefinite" length (to end-of-file)
if (len > 127) {
lenlen += 1;
while (len > 255) {
lenlen += 1;
len = len >> 8;
}
}
if (lenlen) { hex += Hex.fromInt(0x80 + lenlen); }
return hex + Hex.fromInt(str.length/2) + str;
};
// The Integer type has some special rules
ASN1.UInt = function UINT() {
var str = Array.prototype.slice.call(arguments).join('');
var first = parseInt(str.slice(0, 2), 16);
// If the first byte is 0x80 or greater, the number is considered negative
// Therefore we add a '00' prefix if the 0x80 bit is set
if (0x80 & first) { str = '00' + str; }
return ASN1('02', str);
};
// The Bit String type also has a special rule
ASN1.BitStr = function BITSTR() {
var str = Array.prototype.slice.call(arguments).join('');
// '00' is a mask of how many bits of the next byte to ignore
return ASN1('03', '00' + str);
};
EC.toPem = EC.export = EC.pack;