base: support hybrid format

Fix: #91

lib/elliptic/curve/base.js

@@ -251,9 +251,19 @@ BaseCurve.prototype.decodePoint = function decodePoint(bytes, enc) {
  bytes = utils.toArray(bytes, enc);
 
  var len = this.p.byteLength();
- if (bytes[0] === 0x04 && bytes.length - 1 === 2 * len) {
- return this.point(bytes.slice(1, 1 + len),
- bytes.slice(1 + len, 1 + 2 * len));
+
+ // uncompressed, hybrid-odd, hybrid-even
+ if ((bytes[0] === 0x04 || bytes[0] === 0x06 || bytes[0] === 0x07) &&
+ bytes.length - 1 === 2 * len) {
+ if (bytes[0] === 0x06)
+ assert(bytes[bytes.length - 1] % 2 === 0);
+ else if (bytes[0] === 0x07)
+ assert(bytes[bytes.length - 1] % 2 === 1);
+
+ var res = this.point(bytes.slice(1, 1 + len),
+ bytes.slice(1 + len, 1 + 2 * len));
+
+ return res;
  } else if ((bytes[0] === 0x02 || bytes[0] === 0x03) &&
  bytes.length - 1 === len) {
  return this.pointFromX(bytes.slice(1, 1 + len), bytes[0] === 0x03);

test/curve-test.js

@@ -180,6 +180,7 @@ describe('Point codec', function () {
  // Decodes as expected
  assert(curve.decodePoint(definition.encoded, 'hex').eq(p));
  assert(curve.decodePoint(definition.compactEncoded, 'hex').eq(p));
+ assert(curve.decodePoint(definition.hybrid, 'hex').eq(p));
  };
  }
 
@@ -207,6 +208,10 @@ describe('Point codec', function () {
  encoded:
  '04' +
  '79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798' +
+ '483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8',
+ hybrid:
+ '06' +
+ '79be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798' +
  '483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8'
  };
 
@@ -221,6 +226,10 @@ describe('Point codec', function () {
  encoded:
  '04' +
  'fff97bd5755eeea420453a14355235d382f6472f8568a18b2f057a1460297556' +
+ 'ae12777aacfbb620f3be96017f45c560de80f0f6518fe4a03c870c36b075f297',
+ hybrid:
+ '07' +
+ 'fff97bd5755eeea420453a14355235d382f6472f8568a18b2f057a1460297556' +
  'ae12777aacfbb620f3be96017f45c560de80f0f6518fe4a03c870c36b075f297'
  };