98 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			98 lines
		
	
	
		
			3.2 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
;(function () {
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'use strict';
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  var createHash = require('create-hash');
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  var pbkdf2 = require('pbkdf2');
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  var aes = require('browserify-aes');
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  var ec = require('elliptic/lib/elliptic/ec')('p256');
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  function sha256(buf) {
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    return createHash('sha256').update(buf).digest();
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  }
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  function runPbkdf2(password, salt) {
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    // Derived AES key is 128 bit, and the function takes a size in bytes.
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    return pbkdf2.pbkdf2Sync(password, Buffer(salt), 8192, 16, 'sha256');
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  }
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  function encrypt(key, iv, data) {
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    var cipher = aes.createCipheriv('aes-128-gcm', Buffer(key), Buffer(iv));
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    return Buffer.concat([cipher.update(Buffer(data)), cipher.final(), cipher.getAuthTag()]);
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  }
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  function decrypt(key, iv, data) {
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    var decipher = aes.createDecipheriv('aes-128-gcm', Buffer(key), Buffer(iv));
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    decipher.setAuthTag(Buffer(data.slice(-16)));
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    return Buffer.concat([decipher.update(Buffer(data.slice(0, -16))), decipher.final()]);
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  }
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  function bnToBuffer(bn, size) {
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    var buf = bn.toArrayLike(Buffer);
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    if (!size || buf.length === size) {
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      return buf;
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    } else if (buf.length < size) {
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      return Buffer.concat([Buffer(size-buf.length).fill(0), buf]);
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    } else if (buf.length > size) {
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      throw new Error('EC signature number bigger than expected');
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    }
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    throw new Error('invalid size "'+size+'" converting BigNumber to Buffer');
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  }
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  function bnToB64(bn) {
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    var b64 = bnToBuffer(bn).toString('base64');
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    return b64.replace(/\+/g, '-').replace(/\//g, '_').replace(/=*$/, '');
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  }
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  function genEcdsaKeyPair() {
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    var key = ec.genKeyPair();
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    var pubJwk = {
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      key_ops: ['verify']
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    , kty: 'EC'
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    , crv: 'P-256'
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    , x: bnToB64(key.getPublic().getX())
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    , y: bnToB64(key.getPublic().getY())
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    };
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    var privJwk = JSON.parse(JSON.stringify(pubJwk));
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    privJwk.key_ops = ['sign'];
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    privJwk.d = bnToB64(key.getPrivate());
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    return {privateKey: privJwk, publicKey: pubJwk};
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  }
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  function sign(jwk, msg) {
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    var key = ec.keyFromPrivate(Buffer(jwk.d, 'base64'));
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    var sig = key.sign(sha256(msg));
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    return Buffer.concat([bnToBuffer(sig.r, 32), bnToBuffer(sig.s, 32)]);
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  }
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  function verify(jwk, msg, signature) {
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    var key = ec.keyFromPublic({x: Buffer(jwk.x, 'base64'), y: Buffer(jwk.y, 'base64')});
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    var sig = {
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      r: Buffer(signature.slice(0, signature.length/2))
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    , s: Buffer(signature.slice(signature.length/2))
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    };
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    return key.verify(sha256(msg), sig);
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  }
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  function promiseWrap(func) {
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    return function() {
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      var args = arguments;
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      // This fallback file should only be used when the browser doesn't support everything we
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      // need with WebCrypto. Since it is only used in the browser we should be able to assume
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      // that OAUTH3 has been placed in the global scope and that we can access it here.
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      return new OAUTH3.PromiseA(function (resolve) {
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        resolve(func.apply(null, args));
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      });
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    };
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  }
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  exports.sha256  = promiseWrap(sha256);
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  exports.pbkdf2  = promiseWrap(runPbkdf2);
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  exports.encrypt = promiseWrap(encrypt);
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  exports.decrypt = promiseWrap(decrypt);
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  exports.sign    = promiseWrap(sign);
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  exports.verify  = promiseWrap(verify);
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  exports.genEcdsaKeyPair = promiseWrap(genEcdsaKeyPair);
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}());
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