initial commit

pkg/crypto/crypto.go

@@ -0,0 +1,71 @@
+// Copyright (C) 2019 Marius Schellenberger
+
+package crypto
+
+import (
+	"crypto/rand"
+	"errors"
+	"golang.org/x/crypto/argon2"
+	"golang.org/x/crypto/chacha20poly1305"
+	"golang.org/x/crypto/ssh/terminal"
+	"io"
+	"os"
+)
+
+const (
+	SaltSize   = 16
+	PrefixSize = SaltSize + chacha20poly1305.NonceSizeX
+)
+
+func randomBytes(l int) (b []byte) {
+	b = make([]byte, l)
+	_, err := rand.Read(b)
+	if err != nil {
+		panic(err)
+	}
+	return
+}
+
+func kdf(password, salt []byte) []byte {
+	return argon2.IDKey(password, salt, 1, 64*1024, 4, chacha20poly1305.KeySize)
+}
+
+func Password() ([]byte, error) {
+	return terminal.ReadPassword(int(os.Stdin.Fd()))
+}
+
+func Encrypt(pass, src []byte, dst io.Writer) (err error) {
+	salt := randomBytes(SaltSize)
+	nonce := randomBytes(chacha20poly1305.NonceSizeX)
+	aead, err := chacha20poly1305.NewX(kdf(pass, salt))
+	if err != nil {
+		return
+	}
+	_, err = dst.Write(salt)
+	if err != nil {
+		return
+	}
+	_, err = dst.Write(nonce)
+	if err != nil {
+		return
+	}
+	_, err = dst.Write(aead.Seal(nil, nonce, src, nil))
+	return
+}
+
+func Decrypt(pass, src []byte, dst io.Writer) (err error) {
+	if len(src) <= PrefixSize {
+		return errors.New("input file corrupted")
+	}
+	nonce := src[SaltSize:PrefixSize]
+	aead, err := chacha20poly1305.NewX(kdf(pass, src[:SaltSize]))
+	if err != nil {
+		return
+	}
+	dec, err := aead.Open(nil, nonce, src[PrefixSize:], nil)
+	if err != nil {
+		return
+	}
+	_, err = dst.Write(dec)
+	return
+}