Add some comments and fix gofmtHEADmain

5 files changed, 29 insertions, 18 deletions

diff --git a/dec_test.go b/dec_test.go
index b06c722..ea73cd0 100644
--- a/dec_test.go
+++ b/dec_test.go
@@ -169,8 +169,8 @@ func TestDecCmd_Run_Stdin(t *testing.T) {
 	gotContentBuf := new(bytes.Buffer)
 	if err := (&decCmd{
 		password: password,
-		stdin:        bytes.NewReader(encrypted.Bytes()),
-		stdout:       gotContentBuf,
+		stdin:    bytes.NewReader(encrypted.Bytes()),
+		stdout:   gotContentBuf,
 	}).run(); err != nil {
 		t.Fatalf("run failed: %s", err)
 	}
diff --git a/enc.go b/enc.go
index 898fc10..f50665d 100644
--- a/enc.go
+++ b/enc.go
@@ -26,7 +26,7 @@ type encCmd struct {
 	stdout      io.Writer
 }
 
-func (*encCmd) Name() string { return "enc" }
+func (*encCmd) Name() string     { return "enc" }
 func (*encCmd) Synopsis() string { return "encrypt" }
 func (*encCmd) Usage() string {
 	return `usage: sym enc [OPTION]... [FILE]...
diff --git a/enc_test.go b/enc_test.go
index c800652..5dea92d 100644
--- a/enc_test.go
+++ b/enc_test.go
@@ -125,7 +125,7 @@ func TestEncCmd_Run_GeneratePassword(t *testing.T) {
 	password := new(strings.Builder)
 	opts := &encCmd{
 		generatePassword: true,
-		passwordOut:  password,
+		passwordOut:      password,
 	}
 	if err := opts.run(fileName); err != nil {
 		t.Fatalf("encCmd.run(%+v) failed: %s", opts, err)
@@ -151,8 +151,8 @@ func TestEncCmd_Run_Stdin(t *testing.T) {
 	stdout := new(strings.Builder)
 	if err := (&encCmd{
 		password: password,
-		stdin:        strings.NewReader(input),
-		stdout:       stdout,
+		stdin:    strings.NewReader(input),
+		stdout:   stdout,
 	}).run(); err != nil {
 		t.Errorf("encCmd.run failed: %s", err)
 	}
diff --git a/oae.go b/oae.go
index 0389a91..ca2bcf0 100644
--- a/oae.go
+++ b/oae.go
@@ -1,5 +1,16 @@
 package main
 
+// This file is based on the influential paper
+// [Online Authenticated-Encryption and its Nonce-Reuse Misuse-Resistance].
+// It encrypts a stream of data in 1MiB segments using ChaCha20-Poly1305
+// to encrypt each segment. The nonce is a 12 byte value, the first 11
+// bytes of which are a counter that gets incremented for each segment,
+// and the last byte is 0 for every segment except the last segment
+// (where it is 1). Before the encrypted segments, it writes a 32 byte
+// header containing the salt for the password hash.
+//
+// [Online Authenticated-Encryption and its Nonce-Reuse Misuse-Resistance]: https://eprint.iacr.org/2015/189.pdf
+
 import (
 	"bufio"
 	"bytes"
@@ -39,7 +50,7 @@ func (se *segmentEncrypter) nextNonce(lastSegment bool) {
 	// Increment counter
 	for i := 0; ; i++ {
 		if i == len(se.nonce)-1 {
-			panic("counter overflowed")
+			panic("counter overflowed") // impossible, 11 bytes
 		}
 		se.nonce[i]++
 		if se.nonce[i] != 0 {
diff --git a/sym_test.go b/sym_test.go
index 8ae82cc..69bc26a 100644
--- a/sym_test.go
+++ b/sym_test.go
@@ -113,24 +113,24 @@ func TestCommander_Errors(t *testing.T) {
 	t.Parallel()
 
 	for _, tc := range []struct {
-		desc string
-		cmd []string
+		desc       string
+		cmd        []string
 		wantStatus subcommands.ExitStatus
-	} {{
-		desc: "EncUsageError",
-		cmd: []string{"enc", "-g", "-p=asdf", "file.txt"},
+	}{{
+		desc:       "EncUsageError",
+		cmd:        []string{"enc", "-g", "-p=asdf", "file.txt"},
 		wantStatus: subcommands.ExitUsageError,
 	}, {
-		desc: "EncNoSuchFile",
-		cmd: []string{"enc", "-p=asdf", "nonexistent-file.txt"},
+		desc:       "EncNoSuchFile",
+		cmd:        []string{"enc", "-p=asdf", "nonexistent-file.txt"},
 		wantStatus: subcommands.ExitFailure,
 	}, {
-		desc: "DecUsageError",
-		cmd: []string{"dec"},
+		desc:       "DecUsageError",
+		cmd:        []string{"dec"},
 		wantStatus: subcommands.ExitUsageError,
 	}, {
-		desc: "DecNoSuchFile",
-		cmd: []string{"dec", "-p=asdf", "nonexistent-file.txt.enc"},
+		desc:       "DecNoSuchFile",
+		cmd:        []string{"dec", "-p=asdf", "nonexistent-file.txt.enc"},
 		wantStatus: subcommands.ExitFailure,
 	}} {
 		t.Run(tc.desc, func(t *testing.T) {