From: Adam Langley <agl@golang.org>
Date: Sat, 22 Dec 2012 15:50:11 +0000 (-0500)
Subject: crypto/des: add an example to demonstrate EDE2 operation.
X-Git-Tag: go1.1rc2~1560
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=8f1d170fc6758842a1dc89075a050716fa4dc6c3;p=gostls13.git

crypto/des: add an example to demonstrate EDE2 operation.

EDE2 is a rare DES mode that can be implemented with crypto/des, but
it's somewhat non-obvious so this CL adds an example of doing so.

Fixes #3537.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/6721056
---

diff --git a/src/pkg/crypto/des/des_test.go b/src/pkg/crypto/des/des_test.go
index e9fc236299..2e87e99b67 100644
--- a/src/pkg/crypto/des/des_test.go
+++ b/src/pkg/crypto/des/des_test.go
@@ -1503,3 +1503,21 @@ func TestSubstitutionTableKnownAnswerDecrypt(t *testing.T) {
 		}
 	}
 }
+
+func ExampleNewTripleDESCipher() {
+	// NewTripleDESCipher can also be used when EDE2 is required by
+	// duplicating the first 8 bytes of the 16-byte key.
+	ede2Key := []byte("example key 1234")
+
+	var tripleDESKey []byte
+	tripleDESKey = append(tripleDESKey, ede2Key[:16]...)
+	tripleDESKey = append(tripleDESKey, ede2Key[:8]...)
+
+	_, err := NewTripleDESCipher(tripleDESKey)
+	if err != nil {
+		panic(err)
+	}
+
+	// See crypto/cipher for how to use a cipher.Block for encryption and
+	// decryption.
+}