From e12ccae7a96c01dce5e86aa17c27e20644c75a15 Mon Sep 17 00:00:00 2001
From: siddharth ravikumar <s@ricketyspace.net>
Date: Thu, 11 Aug 2022 20:30:53 -0400
Subject: lib: add invmod

---
 lib/rsa_test.go | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

(limited to 'lib/rsa_test.go')

diff --git a/lib/rsa_test.go b/lib/rsa_test.go
index ee71755..4f65468 100644
--- a/lib/rsa_test.go
+++ b/lib/rsa_test.go
@@ -50,3 +50,27 @@ func TestEGCD(t *testing.T) {
 	}
 
 }
+
+func TestInvMod(t *testing.T) {
+	a := big.NewInt(17)
+	b := big.NewInt(3120)
+	e := big.NewInt(2753) // Expected inverse.
+	i, err := invmod(a, b)
+	if err != nil {
+		t.Errorf("invmod(%v,%v) failed: %v", a, b, err)
+	}
+	if i.Cmp(e) != 0 {
+		t.Errorf("gcd(%v,%v) != %v", a, b, e)
+	}
+
+	a = big.NewInt(240)
+	b = big.NewInt(47)
+	e = big.NewInt(19) // Expected inverse.
+	i, err = invmod(a, b)
+	if err != nil {
+		t.Errorf("invmod(%v,%v) failed: %v", a, b, err)
+	}
+	if i.Cmp(e) != 0 {
+		t.Errorf("gcd(%v,%v) != %v", a, b, e)
+	}
+}
-- 
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