From 23ac78333201890deed23576668810e19df2c67e Mon Sep 17 00:00:00 2001
From: David Huie <dahuie@gmail.com>
Date: Mon, 26 Mar 2018 03:46:18 -0700
Subject: ecies: drop randomness parameter from `PrivateKey.Decrypt` (#16374)

The parameter `rand` is unused in `PrivateKey.Decrypt`. Decryption in
the ECIES encryption scheme is deterministic, so randomness isn't
needed.
---
 crypto/ecies/ecies.go      |  6 +++---
 crypto/ecies/ecies_test.go | 20 ++++++++++----------
 2 files changed, 13 insertions(+), 13 deletions(-)

(limited to 'crypto')

diff --git a/crypto/ecies/ecies.go b/crypto/ecies/ecies.go
index 2ed91c895..147418148 100644
--- a/crypto/ecies/ecies.go
+++ b/crypto/ecies/ecies.go
@@ -230,7 +230,7 @@ func symEncrypt(rand io.Reader, params *ECIESParams, key, m []byte) (ct []byte,
 
 // symDecrypt carries out CTR decryption using the block cipher specified in
 // the parameters
-func symDecrypt(rand io.Reader, params *ECIESParams, key, ct []byte) (m []byte, err error) {
+func symDecrypt(params *ECIESParams, key, ct []byte) (m []byte, err error) {
 	c, err := params.Cipher(key)
 	if err != nil {
 		return
@@ -292,7 +292,7 @@ func Encrypt(rand io.Reader, pub *PublicKey, m, s1, s2 []byte) (ct []byte, err e
 }
 
 // Decrypt decrypts an ECIES ciphertext.
-func (prv *PrivateKey) Decrypt(rand io.Reader, c, s1, s2 []byte) (m []byte, err error) {
+func (prv *PrivateKey) Decrypt(c, s1, s2 []byte) (m []byte, err error) {
 	if len(c) == 0 {
 		return nil, ErrInvalidMessage
 	}
@@ -361,6 +361,6 @@ func (prv *PrivateKey) Decrypt(rand io.Reader, c, s1, s2 []byte) (m []byte, err
 		return
 	}
 
-	m, err = symDecrypt(rand, params, Ke, c[mStart:mEnd])
+	m, err = symDecrypt(params, Ke, c[mStart:mEnd])
 	return
 }
diff --git a/crypto/ecies/ecies_test.go b/crypto/ecies/ecies_test.go
index 9cd5c79f7..f33f204d5 100644
--- a/crypto/ecies/ecies_test.go
+++ b/crypto/ecies/ecies_test.go
@@ -270,7 +270,7 @@ func TestEncryptDecrypt(t *testing.T) {
 		t.FailNow()
 	}
 
-	pt, err := prv2.Decrypt(rand.Reader, ct, nil, nil)
+	pt, err := prv2.Decrypt(ct, nil, nil)
 	if err != nil {
 		fmt.Println(err.Error())
 		t.FailNow()
@@ -281,7 +281,7 @@ func TestEncryptDecrypt(t *testing.T) {
 		t.FailNow()
 	}
 
-	_, err = prv1.Decrypt(rand.Reader, ct, nil, nil)
+	_, err = prv1.Decrypt(ct, nil, nil)
 	if err == nil {
 		fmt.Println("ecies: encryption should not have succeeded")
 		t.FailNow()
@@ -301,7 +301,7 @@ func TestDecryptShared2(t *testing.T) {
 	}
 
 	// Check that decrypting with correct shared data works.
-	pt, err := prv.Decrypt(rand.Reader, ct, nil, shared2)
+	pt, err := prv.Decrypt(ct, nil, shared2)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -310,10 +310,10 @@ func TestDecryptShared2(t *testing.T) {
 	}
 
 	// Decrypting without shared data or incorrect shared data fails.
-	if _, err = prv.Decrypt(rand.Reader, ct, nil, nil); err == nil {
+	if _, err = prv.Decrypt(ct, nil, nil); err == nil {
 		t.Fatal("ecies: decrypting without shared data didn't fail")
 	}
-	if _, err = prv.Decrypt(rand.Reader, ct, nil, []byte("garbage")); err == nil {
+	if _, err = prv.Decrypt(ct, nil, []byte("garbage")); err == nil {
 		t.Fatal("ecies: decrypting with incorrect shared data didn't fail")
 	}
 }
@@ -381,7 +381,7 @@ func testParamSelection(t *testing.T, c testCase) {
 		t.FailNow()
 	}
 
-	pt, err := prv2.Decrypt(rand.Reader, ct, nil, nil)
+	pt, err := prv2.Decrypt(ct, nil, nil)
 	if err != nil {
 		fmt.Printf("%s (%s)\n", err.Error(), c.Name)
 		t.FailNow()
@@ -393,7 +393,7 @@ func testParamSelection(t *testing.T, c testCase) {
 		t.FailNow()
 	}
 
-	_, err = prv1.Decrypt(rand.Reader, ct, nil, nil)
+	_, err = prv1.Decrypt(ct, nil, nil)
 	if err == nil {
 		fmt.Printf("ecies: encryption should not have succeeded (%s)\n",
 			c.Name)
@@ -422,7 +422,7 @@ func TestBasicKeyValidation(t *testing.T) {
 
 	for _, b := range badBytes {
 		ct[0] = b
-		_, err := prv.Decrypt(rand.Reader, ct, nil, nil)
+		_, err := prv.Decrypt(ct, nil, nil)
 		if err != ErrInvalidPublicKey {
 			fmt.Println("ecies: validated an invalid key")
 			t.FailNow()
@@ -441,14 +441,14 @@ func TestBox(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	pt, err := prv2.Decrypt(rand.Reader, ct, nil, nil)
+	pt, err := prv2.Decrypt(ct, nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}
 	if !bytes.Equal(pt, message) {
 		t.Fatal("ecies: plaintext doesn't match message")
 	}
-	if _, err = prv1.Decrypt(rand.Reader, ct, nil, nil); err == nil {
+	if _, err = prv1.Decrypt(ct, nil, nil); err == nil {
 		t.Fatal("ecies: encryption should not have succeeded")
 	}
 }
-- 
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