From c09f985b74953a3cce32bddb2de82d3e668e8976 Mon Sep 17 00:00:00 2001
From: tabsoverspaces <d.postolovski@gmail.com>
Date: Wed, 3 Jun 2020 17:44:45 +0200
Subject: [PATCH 1/2] Tests were failing due to Random::Secure.hex receiving
 float argument. Made cast to Int.

---
 src/ecdsa/math.cr | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/src/ecdsa/math.cr b/src/ecdsa/math.cr
index 4051502..c63bd0b 100644
--- a/src/ecdsa/math.cr
+++ b/src/ecdsa/math.cr
@@ -18,23 +18,22 @@ module ECDSA
     end
 
     def self.mod_exp(a : BigInt, exp : BigInt, mod : BigInt)
-      res = BigInt.new(1);
+      res = BigInt.new(1)
       while (exp > 0)
         if ((exp & 1) > 0)
-          res = (res*a).modulo(mod);
+          res = (res*a).modulo(mod)
         end
-        exp >>= 1;
+        exp >>= 1
         a = (a*a).modulo(mod)
       end
-      return res;
+      return res
     end
-  
-    
+
     def self.mod_sqrt(a : BigInt, n : BigInt) : BigInt
       # CAUTION: This works ONLY if n is prime but we do not check - We also do not check if a is a quadratic residue
       # https://en.wikipedia.org/wiki/Quadratic_residue
       if n % 4 == 3
-        return mod_exp(a,(n+1) // 4, n)
+        return mod_exp(a, (n + 1) // 4, n)
       end
       raise Exception.new "Not implemented"
     end
@@ -80,7 +79,7 @@ module ECDSA
       n1, n2 = n2, n1 if n1 > n2
 
       # number of bits of (n1..n2)
-      bin_length = (n2-n1).to_s(2).bytesize
+      bin_length = (n2 - n1).to_s(2).bytesize
       # puts "bin_length of range: #{bin_length}"
 
       # number of bytes required
@@ -90,7 +89,7 @@ module ECDSA
       # puts (n2-n1).to_s(2)
 
       # get random bytes, convert to binary and cut down size
-      s = BigInt.new(Random::Secure.hex(n_bytes), base: 16).to_s(2)[0, bin_length]
+      s = BigInt.new(Random::Secure.hex(n_bytes.to_i), base: 16).to_s(2)[0, bin_length]
       # puts s
       r = n1 + BigInt.new(s, base: 2)
       r = random(n1, n2) if r > n2
@@ -98,4 +97,4 @@ module ECDSA
       return r
     end
   end
-end
\ No newline at end of file
+end

From e10c611240557e1ba30a75dda4c1f2c500b62c95 Mon Sep 17 00:00:00 2001
From: tabsoverspaces <d.postolovski@gmail.com>
Date: Wed, 3 Jun 2020 18:20:54 +0200
Subject: [PATCH 2/2] Removed cast; added floored division.

---
 src/ecdsa/math.cr | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/ecdsa/math.cr b/src/ecdsa/math.cr
index c63bd0b..5d12d9e 100644
--- a/src/ecdsa/math.cr
+++ b/src/ecdsa/math.cr
@@ -83,13 +83,13 @@ module ECDSA
       # puts "bin_length of range: #{bin_length}"
 
       # number of bytes required
-      n_bytes = bin_length / 8
+      n_bytes = bin_length // 8
       n_bytes += 1 unless bin_length % 8 == 0
       # puts "n_bytes required: #{n_bytes}"
       # puts (n2-n1).to_s(2)
 
       # get random bytes, convert to binary and cut down size
-      s = BigInt.new(Random::Secure.hex(n_bytes.to_i), base: 16).to_s(2)[0, bin_length]
+      s = BigInt.new(Random::Secure.hex(n_bytes), base: 16).to_s(2)[0, bin_length]
       # puts s
       r = n1 + BigInt.new(s, base: 2)
       r = random(n1, n2) if r > n2