ECC initial import.

core/bitArray.js

@@ -31,7 +31,7 @@
 sjcl.bitArray = {
   /**
    * Array slices in units of bits.
-   * @param {bitArray a} The array to slice.
+   * @param {bitArray} a The array to slice.
    * @param {Number} bstart The offset to the start of the slice, in bits.
    * @param {Number} bend The offset to the end of the slice, in bits.  If this is undefined,
    * slice until the end of the array.
@@ -42,6 +42,24 @@ sjcl.bitArray = {
     return (bend === undefined) ? a : sjcl.bitArray.clamp(a, bend-bstart);
   },
 
+  /**
+   * Extract a number packed into a bit array.
+   * @param {bitArray} a The array to slice.
+   * @param {Number} bstart The offset to the start of the slice, in bits.
+   * @param {Number} length The length of the number to extract.
+   * @return {Number} The requested slice.
+   */
+  extract: function(a, bstart, blength) {
+    var x, sh = (-bstart-blength) & 31;
+    if ((bstart + blength - 1 ^ bstart) & -32) {
+      // it crosses a boundary
+      x = (a[bstart/32|0] << (32 - sh)) ^ (a[bstart/32+1|0] >>> sh);
+    } else {
+      x = a[bstart/32|0] >>> sh;
+    }
+    return x & ((1<<blength) - 1);
+  },
+
   /**
    * Concatenate two bit arrays.
    * @param {bitArray} a1 The first array.

core/bn.js

@@ -0,0 +1,402 @@
+/**
+ * Constructs a new bignum from another bignum, a number or a hex string.
+ */
+function bn(it) {
+  this.initWith(it);
+}
+
+bn.prototype = {
+  radix: 24,
+  maxMul: 8,
+  _class: bn,
+  
+  copy: function() {
+    return new this._class(this);
+  },
+
+  /**
+   * Initializes this with it, either as a bn, a number, or a hex string.
+   */
+  initWith: function(it) {
+    var i=0, k, n, l;
+    switch(typeof it) {
+    case "object":
+      this.limbs = it.limbs.slice(0);
+      break;
+      
+    case "number":
+      this.limbs = [it];
+      this.normalize();
+      break;
+      
+    case "string":
+      it = it.replace(/^0x/, '');
+      this.limbs = [];
+      // hack
+      k = this.radix / 4;
+      for (i=0; i < it.length; i+=k) {
+        this.limbs.push(parseInt(it.substring(Math.max(it.length - i - k, 0), it.length - i),16));
+      }
+      break;
+
+    default:
+      this.limbs = [0];
+    }
+    return this;
+  },
+
+  /**
+   * Returns true if "this" and "that" are equal.  Calls fullReduce().
+   * Equality test is in constant time.
+   */
+  equals: function(that) {
+    if (typeof that == "number") { that = new this._class(that); }
+    var difference = 0, i;
+    this.fullReduce();
+    that.fullReduce();
+    for (i = 0; i < this.limbs.length || i < that.limbs.length; i++) {
+      difference |= this.getLimb(i) ^ that.getLimb(i);
+    }
+    return (difference === 0);
+  },
+  
+  /**
+   * Get the i'th limb of this, zero if i is too large.
+   */
+  getLimb: function(i) {
+    return (i >= this.limbs.length) ? 0 : this.limbs[i];
+  },
+  
+  /**
+   * Constant time comparison function.
+   * Returns 1 if this >= that, or zero otherwise.
+   */
+  greaterEquals: function(that) {
+    if (typeof that == "number") { that = new this._class(that); }
+    var less = 0, greater = 0, i, a, b;
+    i = Math.max(this.limbs.length, that.limbs.length) - 1;
+    for (; i>= 0; i--) {
+      a = this.getLimb(i);
+      b = that.getLimb(i);
+      greater |= (b - a) & ~less;
+      less |= (a - b) & ~greater
+    }
+    return (greater | ~less) >>> 31;
+  },
+  
+  /**
+   * Convert to a hex string.
+   */
+  toString: function() {
+    this.fullReduce();
+    var out="", i, s, l = this.limbs;
+    for (i=0; i < this.limbs.length; i++) {
+      s = l[i].toString(16);
+      while (i < this.limbs.length - 1 && s.length < 6) {
+        s = "0" + s;
+      }
+      out = s + out;
+    }
+    return "0x"+out;
+  },
+  
+  /** this += that.  Does not normalize. */
+  addM: function(that) {
+    if (typeof(that) !== "object") { that = new this._class(that); }
+    var i;
+    for (i=this.limbs.length; i<that.limbs.length; i++) {
+      this.limbs[i] = 0;
+    }
+    for (i=0; i<that.limbs.length; i++) {
+      this.limbs[i] += that.limbs[i];
+    }
+    return this;
+  },
+
+  /** this -= that.  Does not normalize. */
+  subM: function(that) {
+    if (typeof(that) !== "object") { that = new this._class(that); }
+    var i;
+    for (i=this.limbs.length; i<that.limbs.length; i++) {
+      this.limbs[i] = 0;
+    }
+    for (i=0; i<that.limbs.length; i++) {
+      this.limbs[i] -= that.limbs[i];
+    }
+    return this;
+  },
+  
+  /** this + that.  Does not normalize. */
+  add: function(that) {
+    return this.copy().addM(that);
+  },
+
+  /** this - that.  Does not normalize. */
+  sub: function(that) {
+    return this.copy().subM(that);
+  },
+  
+  /** this * that.  Normalizes and reduces. */
+  mul: function(that) {
+    if (typeof(that) == "number") { that = new this._class(that); }
+    var i, j, a = this.limbs, b = that.limbs, al = a.length, bl = b.length, out = new this._class(), c = out.limbs, ai, ii=this.maxMul;
+
+    for (i=0; i < this.limbs.length + that.limbs.length + 1; i++) {
+      c[i] = 0;
+    }
+    for (i=0; i<al; i++) {
+      ai = a[i];
+      for (j=0; j<bl; j++) {
+        c[i+j] += ai * b[j];
+      }
+     
+      if (!--ii) {
+        ii = this.maxMul;
+        out.cnormalize();
+      }
+    }
+    return out.cnormalize().reduce();
+  },
+
+  /** this ^ 2.  Normalizes and reduces. */
+  square: function() {
+    return this.mul(this);
+  },
+
+  /** this ^ n.  Uses square-and-multiply.  Normalizes and reduces. */
+  power: function(l) {
+    if (typeof(l) == "number") {
+      l = [l];
+    } else if (l.limbs !== undefined) {
+      l = l.normalize().limbs;
+    }
+    var j, out = new this._class(1), pow = this;
+
+    for (i=0; i<l.length; i++) {
+      for (j=0; j<this.radix; j++) {
+        if (l[i] & (1<<j)) {
+          out = out.mul(pow);
+        }
+        pow = pow.square();
+      }
+    }
+    
+    return out;
+  },
+
+  /** Reduce mod a modulus.  Stubbed for subclassing. */
+  reduce: function() {
+    return this;
+  },
+
+  /** Reduce and normalize. */
+  fullReduce: function() {
+    return this.normalize();
+  },
+  
+  /** Propagate carries. */
+  normalize: function() {
+    var carry=0, i, pv = this.placeVal, ipv = this.ipv, l, m, limbs = this.limbs, ll = limbs.length, mask = this.radixMask;
+    for (i=0; i < ll || (carry !== 0 && carry !== -1); i++) {
+      l = (limbs[i]||0) + carry;
+      m = limbs[i] = l & mask;
+      carry = (l-m)*ipv;
+    }
+    if (carry == -1) {
+      limbs[i-1] -= this.placeVal;
+    }
+    return this;
+  },
+
+  /** Constant-time normalize. Does not allocate additional space. */
+  cnormalize: function() {
+    var carry=0, i, ipv = this.ipv, l, m, limbs = this.limbs, ll = limbs.length, mask = this.radixMask;
+    for (i=0; i < ll-1; i++) {
+      l = limbs[i] + carry;
+      m = limbs[i] = l & mask;
+      carry = (l-m)*ipv;
+    }
+    limbs[i] += carry;
+    return this;
+  }
+};
+
+/* Initialization routines for bignum library. */
+(function init(){
+  bn.prototype.ipv = 1 / (bn.prototype.placeVal = Math.pow(2,bn.prototype.radix));
+  bn.prototype.radixMask = (1 << bn.prototype.radix) - 1;
+})();
+
+/**
+ * Creates a new subclass of bn, based on reduction modulo a pseudo-Mersenne prime,
+ * i.e. a prime of the form 2^e + sum(a * 2^b),where the sum is negative and sparse.
+ */
+function pseudoMersennePrime(exponent, coeff) {
+  function p(it) {
+    this.initWith(it);
+    /*if (this.limbs[this.modOffset]) {
+      this.reduce();
+    }*/
+  }
+
+  var ppr = p.prototype = new bn(), i, tmp, mo;
+  mo = ppr.modOffset = Math.ceil(tmp = exponent / ppr.radix);
+  ppr.exponent = exponent;
+  ppr.offset = [];
+  ppr.factor = [];
+  ppr.minOffset = mo;
+  ppr.fullMask = 0;
+  ppr.fullOffset = [];
+  ppr.fullFactor = [];
+  ppr.modulus = p.modulus = new bn(Math.pow(2,exponent));
+  
+  ppr.fullMask = 0|-Math.pow(2, exponent % ppr.radix);
+
+  for (i=0; i<coeff.length; i++) {
+    ppr.offset[i] = Math.floor(coeff[i][0] / ppr.radix - tmp);
+    ppr.fullOffset[i] = Math.ceil(coeff[i][0] / ppr.radix - tmp);
+    ppr.factor[i] = coeff[i][1] * Math.pow(1/2, exponent - coeff[i][0] + ppr.offset[i] * ppr.radix);
+    ppr.fullFactor[i] = coeff[i][1] * Math.pow(1/2, exponent - coeff[i][0] + ppr.fullOffset[i] * ppr.radix);
+    ppr.modulus.addM(new bn(Math.pow(2,coeff[i][0])*coeff[i][1]));
+    ppr.minOffset = Math.min(ppr.minOffset, -ppr.offset[i]); // conservative
+  }
+  ppr._class = p;
+  ppr.modulus.cnormalize();
+
+  /** Approximate reduction mod p.  May leave a number which is negative or slightly larger than p. */
+  ppr.reduce = function() {
+    var i, k, l, mo = this.modOffset, limbs = this.limbs, aff, off = this.offset, ol = this.offset.length, fac = this.factor, ll;
+
+    i = this.minOffset;
+    while (limbs.length > mo) {
+      l = limbs.pop();
+      ll = limbs.length;
+      for (k=0; k<ol; k++) {
+        limbs[ll+off[k]] -= fac[k] * l;
+      }
+      
+      i--;
+      if (i == 0) {
+        limbs.push(0);
+        this.cnormalize();
+        i = this.minOffset;
+      }
+    }
+    this.cnormalize();
+
+    return this;
+  };
+  
+  ppr._strongReduce = (ppr.fullMask == -1) ? ppr.reduce : function() {
+    var limbs = this.limbs, i = limbs.length - 1, l;
+    this.reduce();
+    if (i == this.modOffset - 1) {
+      l = limbs[i] & this.fullMask;
+      limbs[i] -= l;
+      for (k=0; k<this.fullOffset.length; k++) {
+        limbs[i+this.fullOffset[k]] -= this.fullFactor[k] * l;
+      }
+      this.normalize();
+    }
+  };
+
+  /** mostly constant-time, very expensive full reduction. */
+  ppr.fullReduce = function() {
+    var greater, i;
+    // massively above the modulus, may be negative
+    
+    this._strongReduce();
+    // less than twice the modulus, may be negative
+
+    this.addM(this.modulus);
+    this.addM(this.modulus);
+    this.normalize();
+    // probably 2-3x the modulus
+    
+    this._strongReduce();
+    // less than the power of 2.  still may be more than
+    // the modulus
+
+    // HACK: pad out to this length
+    for (i=this.limbs.length; i<this.modOffset; i++) {
+      this.limbs[i] = 0;
+    }
+    
+    // constant-time subtract modulus
+    greater = this.greaterEquals(this.modulus);
+    for (i=0; i<this.limbs.length; i++) {
+      this.limbs[i] -= this.modulus.limbs[i] * greater;
+    }
+    this.cnormalize();
+
+    return this;
+  };
+
+  ppr.inverse = function() {
+    return (this.power(this.modulus.sub(2)));
+  };
+
+  ppr.toBits = function() {
+    this.fullReduce();
+    var i=this.modOffset - 1, w=sjcl.bitArray, e = (this.exponent + 7 & -8) % this.radix || this.radix;
+    out = [w.partial(e, this.getLimb(i))];
+    for (i--; i >= 0; i--) {
+      out = w.concat(out, [w.partial(this.radix, this.getLimb(i))]);
+    }
+    return out;
+  };
+
+  p.fromBits = function(bits) {
+    
+    var out = new this(), words=[], w=sjcl.bitArray, t = this.prototype,
+        l = Math.min(w.bitLength(bits), t.exponent + 7 & -8), e = l % t.radix || t.radix;
+    
+    words[0] = w.extract(bits, 0, e);
+    for (; e < l; e += t.radix) {
+      words.unshift(w.extract(bits, e, t.radix));
+    }
+
+    out.limbs = words;
+    return out;
+  };
+
+  return p;
+}
+
+// a small Mersenne prime
+p127 = pseudoMersennePrime(127, [[0,-1]]);
+
+// Bernstein's prime for Curve25519
+p25519 = pseudoMersennePrime(255, [[0,-19]]);
+
+// NIST primes
+p192 = pseudoMersennePrime(192, [[0,-1],[64,-1]]);
+p224 = pseudoMersennePrime(224, [[0,1],[96,-1]]);
+p256 = pseudoMersennePrime(256, [[0,-1],[96,1],[192,1],[224,-1]]);
+p384 = pseudoMersennePrime(384, [[0,-1],[32,1],[96,-1],[128,-1]]);
+p521 = pseudoMersennePrime(521, [[0,-1]]);
+
+bn.random = function(modulus, paranoia) {
+  if (typeof modulus != "object") { modulus = new bn(modulus); }
+  var words, i, l = modulus.limbs.length, m = modulus.limbs[l-1]+1, out = new bn();
+  while (true) {
+    // get a sequence whose first digits make sense
+    do {
+      words = sjcl.random.randomWords(l, paranoia);
+      if (words[l-1] < 0) { words[l-1] += 0x100000000; }
+    } while (Math.floor(words[l-1] / m) == Math.floor(0x100000000 / m));
+    words[l-1] %= m;
+
+    // mask off all the limbs
+    for (i=0; i<l-1; i++) {
+      words[i] &= modulus.radixMask;
+    }
+
+    // check the rest of the digitssj
+    out.limbs = words;
+    if (!out.greaterEquals(modulus)) {
+      return out;
+    }
+  }
+};
+

core/ecc.js

@@ -0,0 +1,306 @@
+if (window.sjcl == undefined) {
+  window.sjcl = {};
+}
+
+sjcl.ecc = {};
+
+/**
+ * Represents a point on a curve in affine coordinates.
+ * @constructor
+ * @param {sjcl.ecc.curve} curve The curve that this point lies on.
+ * @param {bigInt} x The x coordinate.
+ * @param {bigInt} y The y coordinate.
+ */
+sjcl.ecc.point = function(curve,x,y) {
+  if (x === undefined) {
+    this.isIdentity = true;
+  } else {
+    this.x = x;
+    this.y = y;
+    this.isIdentity = false;
+  }
+  this.curve = curve;
+};
+
+
+
+sjcl.ecc.point.prototype = {
+  toJac: function() {
+    return new sjcl.ecc.pointJac(this.curve, this.x, this.y, new this.curve.field(1));
+  },
+
+  mult: function(k) {
+    return this.toJac().mult(k, this).toAffine();
+  },
+
+  isValid: function() {
+    return this.y.square().equals(this.curve.b.add(this.x.mul(this.curve.a.add(this.x.square()))));
+  },
+
+  toBits: function() {
+    return sjcl.bitArray.concat(this.x.toBits(), this.y.toBits());
+  }
+};
+
+/**
+ * Represents a point on a curve in Jacobian coordinates. Coordinates can be specified as bigInts or strings (which
+ * will be converted to bigInts).
+ *
+ * @constructor
+ * @param {bigInt/string} x The x coordinate.
+ * @param {bigInt/string} y The y coordinate.
+ * @param {bigInt/string} z The z coordinate.
+ * @param {sjcl.ecc.curve} curve The curve that this point lies on.
+ */
+sjcl.ecc.pointJac = function(curve, x, y, z) {
+  if (x === undefined) {
+    this.isIdentity = true;
+  } else {
+    this.x = x;
+    this.y = y;
+    this.z = z;
+    this.isIdentity = false;
+  }
+  this.curve = curve;
+};
+
+sjcl.ecc.pointJac.prototype = {
+  /**
+   * Adds S and T and returns the result in Jacobian coordinates. Note that S must be in Jacobian coordinates and T must be in affine coordinates.
+   * @param {sjcl.ecc.pointJac} S One of the points to add, in Jacobian coordinates.
+   * @param {sjcl.ecc.point} T The other point to add, in affine coordinates.
+   * @return {sjcl.ecc.pointJac} The sum of the two points, in Jacobian coordinates. 
+   */
+  add: function(T) {
+    var S = this;
+    if (S.curve !== T.curve) {
+      throw("sjcl.ecc.add(): Points must be on the same curve to add them!");
+    }
+
+    if (S.isIdentity) {
+      return T.toJac();
+    } else if (T.isIdentity) {
+      return S;
+    }
+
+    var
+      sz2 = S.z.square(),
+      c = T.x.mul(sz2).subM(S.x);
+
+    if (c.equals(0)) {
+      if (S.y.equals(T.y.mul(sz2.mul(S.z)))) {
+        // same point
+        return S.doubl();
+      } else {
+	// inverses
+        return new sjcl.ecc.pointJac(S.curve);
+      }
+    }
+
+    var
+      d = T.y.mul(sz2.mul(S.z)).subM(S.y),
+      c2 = c.square(),
+
+      x1 = d.square(),
+      x2 = c.square().mul(c).addM( S.x.add(S.x).mul(c2) ),
+      x  = x1.subM(x2),
+
+      y1 = S.x.mul(c2).subM(x).mul(d),
+      y2 = S.y.mul(c.square().mul(c)),
+      y  = y1.subM(y2),
+
+      z  = S.z.mul(c);
+
+    //return new sjcl.ecc.pointJac(this.curve,x,y,z);
+    var U = new sjcl.ecc.pointJac(this.curve,x,y,z);
+    if (!U.isValid()) { throw "FOOOOOOOO"; }
+    return U;
+  },
+  
+  /**
+   * doubles this point.
+   * @return {sjcl.ecc.pointJac} The doubled point.
+   */
+  doubl: function() {
+    if (this.isIdentity) { return this; }
+
+    var
+      y2 = this.y.square(),
+      a  = y2.mul(this.x.mul(4)),
+      b  = y2.square().mul(8),
+      z2 = this.z.square(),
+      c  = this.x.sub(z2).mul(3).mul(this.x.add(z2)),
+      x  = c.square().subM(a).subM(a),
+      y  = a.sub(x).mul(c).subM(b),
+      z  = this.y.add(this.y).mul(this.z);
+    return new sjcl.ecc.pointJac(this.curve, x, y, z);
+  },
+
+  /**
+   * Returns a copy of this point converted to affine coordinates.
+   * @return {sjcl.ecc.point} The converted point.
+   */  
+  toAffine: function() {
+    if (this.isIdentity || this.z.equals(0)) {
+      return new sjcl.ecc.point(this.curve);
+    }
+    var zi = this.z.inverse(), zi2 = zi.square();
+    return new sjcl.ecc.point(this.curve, this.x.mul(zi2), this.y.mul(zi2.mul(zi)));
+  },
+  
+  /**
+   * Multiply this point by k and return the answer in Jacobian coordinates.
+   * @param {bigInt} k The coefficient to multiply by.
+   * @param {sjcl.ecc.point} affine This point in affine coordinates.
+   * @return {sjcl.ecc.pointJac} The result of the multiplication, in Jacobian coordinates.
+   */
+  mult: function(k, affine) {
+    if (typeof(k) == "number") {
+      k = [k];
+    } else if (k.limbs !== undefined) {
+      k = k.normalize().limbs;
+    }
+    var i, j, out = this, multiples, aff2;
+    
+    if (affine === undefined) {
+      affine = this.toAffine();
+    }
+
+    if (affine.multiples === undefined) {
+      j = this.doubl();
+      affine.multiples = [new sjcl.ecc.point(this.curve), affine, j.toAffine()];
+      for (i=3; i<16; i++) {
+        j = j.add(affine);
+        affine.multiples[i] = j.toAffine();
+      }
+    }
+    multiples = affine.multiples;
+
+    for (i=k.length-1; i>=0; i--) {
+      for (j=bn.prototype.radix-4; j>=0; j-=4) {
+        out = out.doubl().doubl().doubl().doubl().add(multiples[k[i]>>j & 0xF]);
+      }
+    }
+    
+    return out;
+  },
+
+  isValid: function() {
+    var z2 = this.z.square(), z4 = z2.square(), z6 = z4.mul(z2);
+    return this.y.square().equals(
+             this.curve.b.mul(z6).add(this.x.mul(
+               this.curve.a.mul(z4).add(this.x.square()))));
+  }
+};
+
+/**
+ * Construct an elliptic curve. Most users will not use this and instead start with one of the NIST curves defined below.
+ *
+ * @constructor
+ * @param {bigInt} p The prime modulus.
+ * @param {bigInt} r The prime order of the curve.
+ * @param {bigInt} a The constant a in the equation of the curve y^2 = x^3 + ax + b (for NIST curves, a is always -3).
+ * @param {bigInt} x The x coordinate of a base point of the curve.
+ * @param {bigInt} y The y coordinate of a base point of the curve.
+ */
+sjcl.ecc.curve = function(field, r, a, b, x, y) {
+  this.field = field;
+  this.r = field.prototype.modulus.sub(r);
+  this.a = new field(a);
+  this.b = new field(b);
+  this.G = new sjcl.ecc.point(this, new field(x), new field(y));
+};
+
+sjcl.ecc.curve.prototype.fromBits = function (bits) {
+  var w = sjcl.bitArray, l = this.field.prototype.exponent + 7 & -8;
+  p = new sjcl.ecc.point(this, this.field.fromBits(w.bitSlice(bits, 0, l)),
+                         this.field.fromBits(w.bitSlice(bits, l, 2*l)));
+  if (!p.isValid()) {
+    throw new sjcl.exception.corrupt("not on the curve!");
+  }
+  return p;
+};
+
+sjcl.ecc.p192curve = new sjcl.ecc.curve(
+  p192,
+  "0x662107c8eb94364e4b2dd7ce",
+  -3,
+  "0x64210519e59c80e70fa7e9ab72243049feb8deecc146b9b1",
+  "0x188da80eb03090f67cbf20eb43a18800f4ff0afd82ff1012",
+  "0x07192b95ffc8da78631011ed6b24cdd573f977a11e794811");
+
+sjcl.ecc.p224curve = new sjcl.ecc.curve(
+  p224,
+  "0xe95c1f470fc1ec22d6baa3a3d5c4",
+  -3,
+  "0xb4050a850c04b3abf54132565044b0b7d7bfd8ba270b39432355ffb4",
+  "0xb70e0cbd6bb4bf7f321390b94a03c1d356c21122343280d6115c1d21",
+  "0xbd376388b5f723fb4c22dfe6cd4375a05a07476444d5819985007e34");
+
+sjcl.ecc.p256curve = new sjcl.ecc.curve(
+  p256,
+  "0x4319055358e8617b0c46353d039cdaae",
+  -3,
+  "0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b",
+  "0x6b17d1f2e12c4247f8bce6e563a440f277037d812deb33a0f4a13945d898c296",
+  "0x4fe342e2fe1a7f9b8ee7eb4a7c0f9e162bce33576b315ececbb6406837bf51f5");
+
+sjcl.ecc.p384curve = new sjcl.ecc.curve(
+  p384,
+  "0x389cb27e0bc8d21fa7e5f24cb74f58851313e696333ad68c",
+  -3,
+  "0xb3312fa7e23ee7e4988e056be3f82d19181d9c6efe8141120314088f5013875ac656398d8a2ed19d2a85c8edd3ec2aef",
+  "0xaa87ca22be8b05378eb1c71ef320ad746e1d3b628ba79b9859f741e082542a385502f25dbf55296c3a545e3872760ab7",
+  "0x3617de4a96262c6f5d9e98bf9292dc29f8f41dbd289a147ce9da3113b5f0b8c00a60b1ce1d7e819d7a431d7c90ea0e5f");
+
+sjcl.ecc.curves = {
+  192: sjcl.ecc.p192curve,
+  224: sjcl.ecc.p224curve,
+  256: sjcl.ecc.p256curve,
+  384: sjcl.ecc.p384curve
+};
+
+sjcl.ecc.elGamal = {
+  publicKey: function(curve, point) {
+    this._curve = curve;
+    if (point instanceof Array) {
+      this._point = curve.fromBits(point);
+    } else {
+      this._point = point;
+    }
+  },
+  secretKey: function(curve, exponent) {
+    this._curve = curve;
+    this._exponent = exponent;
+  },
+
+  generateKeys: function(curve, paranoia) {
+    if (typeof curve == "number") {
+      curve = sjcl.ecc.curves[curve];
+      if (curve === undefined) {
+        throw new sjcl.exception.invalid("no such curve");
+      }
+    }
+    var sec = bn.random(curve.r, paranoia), pub = curve.G.mult(sec);
+    return { pub: new sjcl.ecc.elGamal.publicKey(curve, pub),
+             sec: new sjcl.ecc.elGamal.secretKey(curve, sec) };
+  }
+};
+
+sjcl.ecc.elGamal.publicKey.prototype = {
+  kem: function(paranoia) {
+    var sec = bn.random(this._curve.r, paranoia),
+        tag = this._curve.G.mult(sec).toBits(),
+        key = sjcl.hash.sha256.hash(this._point.mult(sec).toBits());
+    return { key: key, tag: tag };
+  }
+};
+
+sjcl.ecc.elGamal.secretKey.prototype = {
+  unkem: function(tag) {
+    return sjcl.hash.sha256.hash(this._curve.fromBits(tag).mult(this._exponent).toBits());
+  }
+};
+
+
+

core/random.js

@@ -47,7 +47,7 @@ sjcl.random = {
     var out = [], i, readiness = this.isReady(paranoia), g;
   
     if (readiness === this._NOT_READY) {
-      throw new sjcl.exception.notready("generator isn't seeded");
+      throw new sjcl.exception.notReady("generator isn't seeded");
     } else if (readiness & this._REQUIRES_RESEED) {
       this._reseedFromPools(!(readiness & this._READY));
     }

core/sjcl.js

@@ -55,6 +55,12 @@ var sjcl = {
     bug: function(message) {
       this.toString = function() { return "BUG: "+this.message; };
       this.message = message;
+    },
+    
+    /** @class Bug or missing feature in SJCL. */
+    notReady: function(message) {
+      this.toString = function() { return "GENERATOR NOT READY: "+this.message; };
+      this.message = message;
     }
   }
 };