diff --git a/lib/dsa.js b/lib/dsa.js
index a16403f9..9b45d519 100644
--- a/lib/dsa.js
+++ b/lib/dsa.js
@@ -59,13 +59,19 @@
       var err, hi, r, s, u1, u2, v, w;
       r = _arg[0], s = _arg[1];
       err = null;
-      hi = this.trunc_hash(h);
-      w = s.modInverse(this.q);
-      u1 = hi.multiply(w).mod(this.q);
-      u2 = r.multiply(w).mod(this.q);
-      v = this.g.modPow(u1, this.p).multiply(this.y.modPow(u2, this.p)).mod(this.p).mod(this.q);
-      if (!v.equals(r)) {
-        err = new Error("verification failed");
+      if ((r.signum() <= 0) || (r.compareTo(this.q) >= 0)) {
+        err = new Error("bad r");
+      } else if ((s.signum() <= 0) || (s.compareTo(this.q) >= 0)) {
+        err = new Error("bad s");
+      } else {
+        hi = this.trunc_hash(h);
+        w = s.modInverse(this.q);
+        u1 = hi.multiply(w).mod(this.q);
+        u2 = r.multiply(w).mod(this.q);
+        v = this.g.modPow(u1, this.p).multiply(this.y.modPow(u2, this.p)).mod(this.p).mod(this.q);
+        if (!v.equals(r)) {
+          err = new Error("verification failed");
+        }
       }
       return cb(err);
     };
@@ -102,7 +108,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/dsa.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/dsa.iced",
             funcname: "Priv.sign"
           });
           SRF().random_zn(q.subtract(bn.nbv(2)), __iced_deferrals.defer({
@@ -111,7 +117,7 @@
                 return k = arguments[0];
               };
             })(),
-            lineno: 76
+            lineno: 81
           }));
           __iced_deferrals._fulfill();
         });
@@ -200,7 +206,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/dsa.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/dsa.iced",
             funcname: "Pair.pad_and_sign"
           });
           _this.priv.sign(h, __iced_deferrals.defer({
@@ -209,7 +215,7 @@
                 return sig = arguments[0];
               };
             })(),
-            lineno: 128
+            lineno: 133
           }));
           __iced_deferrals._fulfill();
         });
diff --git a/lib/ecc/ecdsa.js b/lib/ecc/ecdsa.js
index 58d519f8..3088c591 100644
--- a/lib/ecc/ecdsa.js
+++ b/lib/ecc/ecdsa.js
@@ -57,9 +57,9 @@
       r = _arg[0], s = _arg[1];
       err = null;
       hi = this.trunc_hash(h);
-      if ((r.signum() <= 0) || (r.compareTo(this.curve.p) > 0)) {
+      if ((r.signum() <= 0) || (r.compareTo(this.curve.n) >= 0)) {
         err = new Error("bad r");
-      } else if ((r.signum() <= 0) || (s.compareTo(this.curve.p) > 0)) {
+      } else if ((s.signum() <= 0) || (s.compareTo(this.curve.n) >= 0)) {
         err = new Error("bad s");
       } else {
         n = this.curve.n;
@@ -67,9 +67,13 @@
         u1 = hi.multiply(w).mod(n);
         u2 = r.multiply(w).mod(n);
         p = this.curve.G.multiplyTwo(u1, this.R, u2);
-        v = p.affineX.mod(n);
-        if (!v.equals(r)) {
+        if (this.curve.isInfinity(p)) {
           err = new Error("verification failed");
+        } else {
+          v = p.affineX.mod(n);
+          if (!v.equals(r)) {
+            err = new Error("verification failed");
+          }
         }
       }
       return cb(err);
@@ -107,7 +111,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/ecc/ecdsa.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/ecc/ecdsa.iced",
             funcname: "Priv.sign"
           });
           _this.pub.curve.random_scalar(__iced_deferrals.defer({
@@ -116,7 +120,7 @@
                 return k = arguments[0];
               };
             })(),
-            lineno: 79
+            lineno: 80
           }));
           __iced_deferrals._fulfill();
         });
@@ -212,7 +216,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/ecc/ecdsa.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/ecc/ecdsa.iced",
             funcname: "Pair.pad_and_sign"
           });
           _this.priv.sign(h, __iced_deferrals.defer({
@@ -221,7 +225,7 @@
                 return sig = arguments[0];
               };
             })(),
-            lineno: 134
+            lineno: 135
           }));
           __iced_deferrals._fulfill();
         });
diff --git a/lib/elgamal.js b/lib/elgamal.js
index 9049e5f1..77d9027a 100644
--- a/lib/elgamal.js
+++ b/lib/elgamal.js
@@ -52,7 +52,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/elgamal.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/elgamal.iced",
             funcname: "Pub.encrypt"
           });
           SRF().random_zn(_this.p.subtract(bn.nbv(2)), __iced_deferrals.defer({
@@ -100,10 +100,15 @@
     };
 
     Priv.prototype.decrypt = function(c, cb) {
-      var p, ret;
+      var err, p, ret;
+      err = null;
       p = this.pub.p;
-      ret = c[0].modPow(this.x, p).modInverse(p).multiply(c[1]).mod(p);
-      return cb(null, ret);
+      if (((c[0].signum() <= 0) || (c[0].compareTo(p) >= 0)) || ((c[1].signum() <= 0) || (c[1].compareTo(p) >= 0))) {
+        err = new Error("invalid message");
+      } else {
+        ret = c[0].modPow(this.x, p).modInverse(p).multiply(c[1]).mod(p);
+      }
+      return cb(err, ret);
     };
 
     return Priv;
@@ -173,7 +178,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/elgamal.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/elgamal.iced",
             funcname: "Pair.pad_and_encrypt"
           });
           eme_pkcs1_encode(data, _this.pub.p.mpi_byte_length(), __iced_deferrals.defer({
@@ -183,7 +188,7 @@
                 return m = arguments[1];
               };
             })(),
-            lineno: 112
+            lineno: 117
           }));
           __iced_deferrals._fulfill();
         });
@@ -194,7 +199,7 @@
               (function(__iced_k) {
                 __iced_deferrals = new iced.Deferrals(__iced_k, {
                   parent: ___iced_passed_deferral,
-                  filename: "/Users/max/src/keybase/kbpgp/src/elgamal.iced",
+                  filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/elgamal.iced",
                   funcname: "Pair.pad_and_encrypt"
                 });
                 _this.pub.encrypt(m, __iced_deferrals.defer({
@@ -203,7 +208,7 @@
                       return c_mpis = arguments[0];
                     };
                   })(),
-                  lineno: 114
+                  lineno: 119
                 }));
                 __iced_deferrals._fulfill();
               })(function() {
@@ -230,7 +235,7 @@
         return (function(__iced_k) {
           __iced_deferrals = new iced.Deferrals(__iced_k, {
             parent: ___iced_passed_deferral,
-            filename: "/Users/max/src/keybase/kbpgp/src/elgamal.iced",
+            filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/elgamal.iced",
             funcname: "Pair.decrypt_and_unpad"
           });
           _this.priv.decrypt(ciphertext.c(), __iced_deferrals.defer({
@@ -240,7 +245,7 @@
                 return m = arguments[1];
               };
             })(),
-            lineno: 122
+            lineno: 127
           }));
           __iced_deferrals._fulfill();
         });
@@ -332,7 +337,7 @@
               (function(__iced_k) {
                 __iced_deferrals = new iced.Deferrals(__iced_k, {
                   parent: ___iced_passed_deferral,
-                  filename: "/Users/max/src/keybase/kbpgp/src/elgamal.iced",
+                  filename: "/Users/michal/SourceCode/keybase/go/src/github.com/keybase/kbpgp/src/elgamal.iced",
                   funcname: "Output.hide"
                 });
                 key.hide({
@@ -346,7 +351,7 @@
                       return tmp = arguments[1];
                     };
                   })(),
-                  lineno: 164
+                  lineno: 169
                 }));
                 __iced_deferrals._fulfill();
               })(function() {
diff --git a/src/dsa.iced b/src/dsa.iced
index 6ea21adc..4a2a4684 100644
--- a/src/dsa.iced
+++ b/src/dsa.iced
@@ -42,12 +42,17 @@ class Pub extends BaseKey
 
   verify : ([r, s], h, cb) ->
     err = null
-    hi = @trunc_hash(h)
-    w = s.modInverse @q
-    u1 = hi.multiply(w).mod(@q)
-    u2 = r.multiply(w).mod(@q)
-    v = @g.modPow(u1, @p).multiply(@y.modPow(u2, @p)).mod(@p).mod(@q)
-    err = new Error "verification failed" unless v.equals(r)
+    if ((r.signum() <= 0) or (r.compareTo(@q) >= 0))
+      err = new Error "bad r"
+    else if ((s.signum() <= 0) or (s.compareTo(@q) >= 0))
+      err = new Error "bad s"
+    else
+      hi = @trunc_hash(h)
+      w = s.modInverse @q
+      u1 = hi.multiply(w).mod(@q)
+      u2 = r.multiply(w).mod(@q)
+      v = @g.modPow(u1, @p).multiply(@y.modPow(u2, @p)).mod(@p).mod(@q)
+      err = new Error "verification failed" unless v.equals(r)
     cb err
 
 #=================================================================
diff --git a/src/ecc/ecdsa.iced b/src/ecc/ecdsa.iced
index df781720..444db4df 100644
--- a/src/ecc/ecdsa.iced
+++ b/src/ecc/ecdsa.iced
@@ -39,20 +39,21 @@ class Pub extends BaseEccKey
     err = null
     hi = @trunc_hash(h)
 
-    if ((r.signum() <= 0) or (r.compareTo(@curve.p) > 0))
+    if ((r.signum() <= 0) or (r.compareTo(@curve.n) >= 0))
       err = new Error "bad r"
-    else if ((r.signum() <= 0) or (s.compareTo(@curve.p) > 0))
+    else if ((s.signum() <= 0) or (s.compareTo(@curve.n) >= 0))
       err = new Error "bad s"
     else
-
       n = @curve.n
       w = s.modInverse n
       u1 = hi.multiply(w).mod(n)
       u2 = r.multiply(w).mod(n)
       p = @curve.G.multiplyTwo(u1,@R,u2)
-
-      v = p.affineX.mod(n)
-      err = new Error "verification failed" unless v.equals(r)
+      if @curve.isInfinity(p)
+        err = new Error "verification failed"
+      else
+        v = p.affineX.mod(n)
+        err = new Error "verification failed" unless v.equals(r)
     cb err
 
 #=================================================================
diff --git a/src/elgamal.iced b/src/elgamal.iced
index 31065883..bbbac69f 100644
--- a/src/elgamal.iced
+++ b/src/elgamal.iced
@@ -63,9 +63,14 @@ class Priv extends BaseKey
   #----------------
 
   decrypt : (c, cb) ->
+    err = null
     p = @pub.p
-    ret = c[0].modPow(@x,p).modInverse(p).multiply(c[1]).mod(p)
-    cb null, ret
+    if ((c[0].signum() <= 0) or (c[0].compareTo(p) >= 0)) or
+        ((c[1].signum() <= 0) or (c[1].compareTo(p) >= 0))
+      err = new Error "invalid message"
+    else
+      ret = c[0].modPow(@x,p).modInverse(p).multiply(c[1]).mod(p)
+    cb err, ret
 
 #=================================================================
 
diff --git a/test/browser/main.iced b/test/browser/main.iced
index fa695243..c585db92 100644
--- a/test/browser/main.iced
+++ b/test/browser/main.iced
@@ -1,5 +1,6 @@
 
 mods =
+  bn : require '../files/bn.iced'
   brainpool256 : require '../files/brainpool256.iced'
   brainpool384: require '../files/brainpool384.iced'
   brainpool512: require '../files/brainpool512.iced'
diff --git a/test/files/bn.iced b/test/files/bn.iced
new file mode 100644
index 00000000..60bfee4b
--- /dev/null
+++ b/test/files/bn.iced
@@ -0,0 +1,41 @@
+{nbs,BigInteger} = require '../../lib/bn'
+
+#=================================================================
+
+exports.valid_mod_inverse_returns_inverse = (T, cb) ->
+  cases = [
+    { a : '3', m : '257', inverse : '86' }
+    { a : '10', m : '17', inverse : '12' }
+    { a : '101', m : '257', inverse : '28' }
+  ]
+
+  for c in cases
+    a = nbs c.a
+    m = nbs c.m
+    inv = a.modInverse m
+    T.equal inv.toString(), c.inverse, "#{c.a}^-1 mod #{c.m}"
+    T.equal a.multiply(inv).mod(m).toString(), '1', "#{c.a} * inverse == 1 mod #{c.m}"
+  cb()
+
+#=================================================================
+
+exports.invalid_mod_inverse_returns_zero_when_gcd_is_not_one = (T, cb) ->
+  cases = [
+    { a : '2', m : '4' }
+    { a : '6', m : '9' }
+    { a : '101', m : '101' }
+    { a : '202', m : '101' }
+    { a : '3', m : '0' }
+  ]
+
+  for c in cases
+    a = nbs c.a
+    m = nbs c.m
+    inv = a.modInverse m
+    T.equal inv.signum(), 0, "#{c.a}^-1 mod #{c.m} returned zero"
+    T.equal inv.toString(), '0'
+    unless m.signum() is 0
+      T.assert not(a.gcd(m).equals(BigInteger.ONE)), "#{c.a} and #{c.m} are not coprime"
+  cb()
+
+#=================================================================