1 files changed, 133 insertions, 0 deletions
diff --git a/lib/rsa_test.go b/lib/rsa_test.go
new file mode 100644
index 0000000..d26ee2c
--- /dev/null
+++ b/lib/rsa_test.go
@@ -0,0 +1,133 @@
+// Copyright © 2021 siddharth ravikumar <s@ricketyspace.net>
+// SPDX-License-Identifier: ISC
+
+package lib
+
+import (
+	"math/big"
+	"testing"
+)
+
+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)
+		return
+	}
+	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)
+		return
+	}
+	if i.Cmp(e) != 0 {
+		t.Errorf("gcd(%v,%v) != %v", a, b, e)
+	}
+
+	a = big.NewInt(11)
+	b = big.NewInt(26)
+	e = big.NewInt(19) // Expected inverse.
+	i, err = InvMod(a, b)
+	if err != nil {
+		t.Errorf("InvMod(%v,%v) failed: %v", a, b, err)
+		return
+	}
+	if i.Cmp(e) != 0 {
+		t.Errorf("gcd(%v,%v) != %v", a, b, e)
+	}
+
+	a = big.NewInt(3)
+	b = big.NewInt(7)
+	e = big.NewInt(5) // Expected inverse.
+	i, err = InvMod(a, b)
+	if err != nil {
+		t.Errorf("InvMod(%v,%v) failed: %v", a, b, err)
+		return
+	}
+	if i.Cmp(e) != 0 {
+		t.Errorf("gcd(%v,%v) != %v", a, b, e)
+	}
+}
+
+func TestRSAGenKey(t *testing.T) {
+	pair, err := RSAGenKey()
+	if err != nil {
+		t.Errorf("genkey: %v", err)
+		return
+	}
+	if pair.Public == nil {
+		t.Error("genkey: pub key is nil")
+		return
+	}
+	if pair.Public.e.Cmp(big.NewInt(0)) < 1 {
+		t.Error("genkey: e is invalid")
+		return
+	}
+	if pair.Public.n.Cmp(big.NewInt(0)) < 1 {
+		t.Error("genkey: n is invalid")
+		return
+	}
+	if pair.Private == nil {
+		t.Error("genkey: private key is nil")
+		return
+	}
+	if pair.Private.d.Cmp(big.NewInt(0)) < 1 {
+		t.Error("genkey: d is invalid")
+		return
+	}
+	if pair.Private.n.Cmp(big.NewInt(0)) < 1 {
+		t.Error("genkey: n is invalid")
+		return
+	}
+	if pair.Public.n.Cmp(pair.Private.n) != 0 {
+		t.Error("genkey: public.n != private.n")
+		return
+	}
+}
+
+func TestRSAEncryptDecrypt(t *testing.T) {
+	pair, err := RSAGenKey()
+	if err != nil {
+		t.Errorf("genkey: %v", err)
+		return
+	}
+	pub := pair.Public
+	prv := pair.Private
+
+	// [1] Encrypt.
+	msg := []byte("42")
+	enc := pub.Encrypt(msg)
+	if len(enc) < 1 {
+		t.Errorf("encrypt failed: %v", enc)
+		return
+	}
+	// [1] Decrypt.
+	dec := prv.Decrypt(enc)
+	if !BytesEqual(msg, dec) {
+		t.Errorf("decrypt failed: %v", dec)
+		return
+	}
+
+	// [2] Encrypt.
+	msg = []byte("0xd1a4a6e870b40a261827f17741c19facf80d01a537d55e59abe5d615d961a23f")
+	enc = pub.Encrypt(msg)
+	if len(enc) < 1 {
+		t.Errorf("encrypt failed: %v", enc)
+		return
+	}
+	// [2] Decrypt.
+	dec = prv.Decrypt(enc)
+	if !BytesEqual(msg, dec) {
+		t.Errorf("decrypt failed: %v", dec)
+		return
+	}
+}