1 files changed, 85 insertions, 0 deletions
diff --git a/doc/talks/io2010/decrypt.go b/doc/talks/io2010/decrypt.go
new file mode 100644
index 000000000..0a6c006e2
--- /dev/null
+++ b/doc/talks/io2010/decrypt.go
@@ -0,0 +1,85 @@
+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This code differs from the slides in that it handles errors.
+
+package main
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"compress/gzip"
+	"io"
+	"log"
+	"os"
+)
+
+func EncryptAndGzip(dstfile, srcfile string, key, iv []byte) os.Error {
+	r, err := os.Open(srcfile)
+	if err != nil {
+		return err
+	}
+	var w io.Writer
+	w, err = os.Create(dstfile)
+	if err != nil {
+		return err
+	}
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return err
+	}
+	w = cipher.StreamWriter{S: cipher.NewOFB(c, iv), W: w}
+	w2, err := gzip.NewWriter(w)
+	if err != nil {
+		return err
+	}
+	defer w2.Close()
+	_, err = io.Copy(w2, r)
+	return err
+}
+
+func DecryptAndGunzip(dstfile, srcfile string, key, iv []byte) os.Error {
+	f, err := os.Open(srcfile)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	c, err := aes.NewCipher(key)
+	if err != nil {
+		return err
+	}
+	r := cipher.StreamReader{S: cipher.NewOFB(c, iv), R: f}
+	r2, err := gzip.NewReader(r)
+	if err != nil {
+		return err
+	}
+	w, err := os.Create(dstfile)
+	if err != nil {
+		return err
+	}
+	defer w.Close()
+	_, err = io.Copy(w, r2)
+	return err
+}
+
+func main() {
+	err := EncryptAndGzip(
+		"/tmp/passwd.gz",
+		"/etc/passwd",
+		make([]byte, 16),
+		make([]byte, 16),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = DecryptAndGunzip(
+		"/dev/stdout",
+		"/tmp/passwd.gz",
+		make([]byte, 16),
+		make([]byte, 16),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+}