From 14d584e3302a4b4984a9e051dd403e3896058aba Mon Sep 17 00:00:00 2001
From: trivernis <trivernis@gmail.com>
Date: Sat, 15 Feb 2020 13:25:05 +0100
Subject: [PATCH] Add masked password input and hash

- Add password input that doesn't print the password
- Change the password to be hashed with sha512_256 to a 32 byte slice
---
 cryptpng.go | 31 ++++++++++++++++++++-----------
 go.mod      |  2 ++
 go.sum      |  8 ++++++++
 3 files changed, 30 insertions(+), 11 deletions(-)
 create mode 100644 go.sum

diff --git a/cryptpng.go b/cryptpng.go
index 4376bc8..20efd3f 100644
--- a/cryptpng.go
+++ b/cryptpng.go
@@ -1,10 +1,10 @@
 package main
 
 import (
-	"bufio"
 	"crypto/aes"
 	"crypto/cipher"
 	"crypto/rand"
+	"crypto/sha512"
 	"encoding/base64"
 	"errors"
 	"flag"
@@ -13,6 +13,9 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"syscall"
+
+	"golang.org/x/crypto/ssh/terminal"
 )
 
 func check(err error) {
@@ -79,6 +82,9 @@ func DecryptDataPng(f *os.File, fout *os.File) {
 	cryptChunk := png.GetChunk(chunkName)
 	if cryptChunk != nil {
 		data, err := decryptData(cryptChunk.data)
+		if err != nil {
+			log.Println("\nThe provided password is probably incorrect.")
+		}
 		check(err)
 		_, err = fout.Write(data)
 		check(err)
@@ -89,23 +95,26 @@ func DecryptDataPng(f *os.File, fout *os.File) {
 
 // creates an encrypted png chunk
 func encryptData(data []byte) ([]byte, error) {
-	reader := bufio.NewReader(os.Stdin)
-	fmt.Print("Password: ")
-	pw, _ := reader.ReadString('\n')
-	key := make([]byte, 32 - len(pw))
-	key = append(key, []byte(pw)...)
+	key := readPassword()
 	return encrypt(key, data)
 }
 
 func decryptData(data []byte) ([]byte, error) {
-	reader := bufio.NewReader(os.Stdin)
-	fmt.Print("Password: ")
-	pw, _ := reader.ReadString('\n')
-	key := make([]byte, 32 - len(pw))
-	key = append(key, []byte(pw)...)
+	key := readPassword()
 	return decrypt(key, data)
 }
 
+// reads a password from the terminal
+// turns off the input for the typing of the password
+func readPassword() []byte {
+	fmt.Print("Password: ")
+	bytePw, err := terminal.ReadPassword(int(syscall.Stdin))
+	check(err)
+	hash := sha512.New512_256()
+	hash.Write(bytePw)
+	return hash.Sum(nil)
+}
+
 // encrypt and decrypt functions taken from
 // https://stackoverflow.com/questions/18817336/golang-encrypting-a-string-with-aes-and-base64
 
diff --git a/go.mod b/go.mod
index 6e84974..63a5d47 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module github.com/trivernis/cryptpng
 
 go 1.13
+
+require golang.org/x/crypto v0.0.0-20200214034016-1d94cc7ab1c6
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..d5514fc
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,8 @@
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20200214034016-1d94cc7ab1c6 h1:Sy5bstxEqwwbYs6n0/pBuxKENqOeZUgD45Gp3Q3pqLg=
+golang.org/x/crypto v0.0.0-20200214034016-1d94cc7ab1c6/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=