go-bip39 gone from go.mod and go.sum (#72)

What is on `next`, reviewed.

- go-bip39 is gone from `go.mod` and `go.sum`: keyfunc now requires `sneak/secret` at `ef0ae90`, the commit that gives `secret` its own copy (sneak/secret#130). No derived key, mnemonic or test vector changes.

To know before merging:

- `secret`'s module is now `sneak.berlin/go/secret` (sneak/secret#43), so keyfunc's requirement, its two imports of `secret`'s `bip85` package and one README sentence use that path. The Go module proxy serves that path, so `go install` keeps working.

Model: opus-5-5
Reviewed-on: #72
Co-authored-by: clawbot <sneak+clawbot@sneak.cloud>

README.md

@@ -100,9 +100,7 @@ m/83696968'/<app>'/<n>'
   to one tool. Each key type's number is spelled the way BIP-85 spells its own
   RSA application (`828365` is the ASCII codes of `R`, `S`, `A` written out):
   SSH is `838372` (`S` `S` `H`), age is `657169` (`A` `G` `E`).
-- `n` is the key index, a decimal number: flag `--index` / `-n`, default `0`. A
+- `n` is the key index: flag `--index` / `-n`, default `0`.
-  leading zero is still decimal (`-n 010` is index 10); a base prefix, an
-  underscore or a sign (`0x10`, `1_0`, `+1`) is refused.
 
 ## Giving it the mnemonic
 
@@ -119,17 +117,14 @@ order; the first one found wins:
 4. A prompt on the terminal with echo turned off.
 
 If none of these is available and standard input is not a terminal, the tool
-refuses and exits with status 1. A mnemonic that is empty, does not have 12, 15,
+refuses and exits with status 1. A mnemonic that fails the BIP-39 checksum is
-18, 21 or 24 words, has a word that is not on the BIP-39 word list, or fails the
+refused with a message saying so. Keys are derived from the mnemonic's words
-BIP-39 checksum is refused with a message saying which. A word that is not on
+joined by single spaces, whatever whitespace is around or between them, so one
-the list is named by its position, never printed. Keys are derived from the
+word per line, tabs or extra spaces give the same keys.
-mnemonic's words joined by single spaces, whatever whitespace is around or
-between them, so one word per line, tabs or extra spaces give the same keys.
 
 `KEYFUNC_MNEMONIC` and `KEYFUNC_MNEMONIC_COMMAND` are removed from the
-environment before the mnemonic command, the system `ssh` (`keyfunc ssh to`) and
+environment before the system `ssh` (`keyfunc ssh to`) and `sftp`
-`sftp` (`keyfunc ssh install`) are started, so the mnemonic is never handed on
+(`keyfunc ssh install`) are started, so the mnemonic is never handed on to them.
-to them.
 
 Every command takes `--index` / `-n` and `--mnemonic-command`, and has `--help`.
 `keyfunc --version` prints the version. `make build` stamps it; a binary

internal/cli/cli_test.go

@@ -2,7 +2,6 @@ package cli_test
 
 import (
 	"bytes"
-	"strconv"
 	"strings"
 	"testing"
 
@@ -107,56 +106,6 @@ func TestAnIndexWithNoHardenedChildIsRefused(t *testing.T) {
 	require.Empty(t, out)
 }
 
-func TestAnIndexWithALeadingZeroIsDecimal(t *testing.T) {
-	t.Setenv(mnemonic.Variable, example())
-
-	line := run(t, "ssh", "pub", "-n", "010")
-	require.Equal(t, run(t, "ssh", "pub", "-n", "10"), line)
-	require.True(t,
-		strings.HasSuffix(strings.TrimSpace(line), " keyfunc/ssh/10"),
-	)
-}
-
-// The mnemonic command in these runs fails, so a refusal naming the
-// flag shows that the number was refused before the mnemonic was
-// looked for.
-func TestAnIndexThatIsNotDecimalDigitsIsRefused(t *testing.T) {
-	t.Parallel()
-
-	for _, index := range []string{"0x10", "1_0", "+1", "-1", ""} {
-		t.Run(index, func(t *testing.T) {
-			t.Parallel()
-
-			out, err := execute(t,
-				"ssh", "pub", "-n", index, "--mnemonic-command", "exit 1",
-			)
-			require.ErrorIs(t, err, strconv.ErrSyntax)
-			require.ErrorContains(t, err, "--index")
-			require.Empty(t, out)
-		})
-	}
-}
-
-// Neither a command group nor --version reads the index, so these
-// show that it is refused while the flags are parsed.
-func TestAnIndexNotInDecimalIsRefusedBeforeAnyCommandRuns(t *testing.T) {
-	t.Parallel()
-
-	for _, args := range [][]string{
-		{"ssh", "-n", "0x10"},
-		{"-n", "0x10", "--version"},
-	} {
-		t.Run(strings.Join(args, " "), func(t *testing.T) {
-			t.Parallel()
-
-			out, err := execute(t, args...)
-			require.ErrorIs(t, err, strconv.ErrSyntax)
-			require.ErrorContains(t, err, "--index")
-			require.Empty(t, out)
-		})
-	}
-}
-
 func TestTheMnemonicCommandIsUsed(t *testing.T) {
 	t.Setenv(mnemonic.Variable, "")
 
@@ -189,22 +138,6 @@ func TestALengthTheToolDoesNotOfferIsRefused(t *testing.T) {
 	require.Empty(t, out)
 }
 
-func TestTheWordCountIsDecimal(t *testing.T) {
-	t.Setenv(mnemonic.Variable, example())
-
-	words := strings.Fields(run(t, "mnemonic", "--words", "012"))
-	require.Len(t, words, twelve)
-
-	// As for the index, the failing mnemonic command shows that the
-	// number was refused first.
-	out, err := execute(t,
-		"mnemonic", "--words", "0x18", "--mnemonic-command", "exit 1",
-	)
-	require.ErrorIs(t, err, strconv.ErrSyntax)
-	require.ErrorContains(t, err, "--words")
-	require.Empty(t, out)
-}
-
 // run executes the tool with the given arguments and returns what it
 // wrote to standard output.
 func run(t *testing.T, args ...string) string {

internal/cli/mnemonic/mnemonic.go

@@ -31,9 +31,8 @@ func Command() *cobra.Command {
 		},
 	}
 
-	words := options.Decimal(childmnemonic.DefaultWords)
+	cmd.Flags().Uint32(
-	cmd.Flags().Var(
+		"words", childmnemonic.DefaultWords,
-		&words, "words",
 		"how long the child mnemonic is: 12, 18 or 24 words",
 	)
 

internal/cli/options/options.go

@@ -4,7 +4,6 @@ package options
 
 import (
 	"fmt"
-	"strconv"
 
 	"github.com/spf13/cobra"
 	"sneak.berlin/go/keyfunc/internal/mnemonic"
@@ -17,8 +16,8 @@ func Add(cmd *cobra.Command) {
 		"mnemonic-command", "",
 		"shell command whose output is the mnemonic",
 	)
-	cmd.PersistentFlags().VarP(
+	cmd.PersistentFlags().Uint32P(
-		new(Decimal), "index", "n",
+		"index", "n", 0,
 		"which key to derive",
 	)
 }
@@ -42,33 +41,3 @@ func Mnemonic(cmd *cobra.Command) (string, error) {
 
 	return mnemonic.Read(cmd.Context(), command)
 }
-
-// Decimal is a flag value for a number written in decimal digits only.
-// The flag library's own uint32 flags read 010 as octal 8 and also
-// take 0x10 or 1_0.
-type Decimal uint32
-
-// String returns the number in decimal digits.
-func (d *Decimal) String() string {
-	return strconv.FormatUint(uint64(*d), 10)
-}
-
-// Set reads text as a decimal number that fits in 32 bits: a leading
-// zero is still decimal, and a base prefix, an underscore or a sign is
-// refused.
-func (d *Decimal) Set(text string) error {
-	number, err := strconv.ParseUint(text, 10, 32)
-	if err != nil {
-		return err
-	}
-
-	*d = Decimal(number)
-
-	return nil
-}
-
-// Type is what --help shows as the flag's type, and what GetUint32
-// checks before it reads the value back.
-func (d *Decimal) Type() string {
-	return "uint32"
-}

internal/cli/ssh/install.go

@@ -16,7 +16,6 @@ import (
 
 	"github.com/spf13/cobra"
 	"sneak.berlin/go/keyfunc/internal/cli/signals"
-	"sneak.berlin/go/keyfunc/internal/mnemonic"
 )
 
 // Where the key goes on the host and what the file it arrives in is
@@ -221,7 +220,7 @@ func session(
 
 	//nolint:gosec // the options are the user's own, meant for sftp
 	command := exec.CommandContext(cmd.Context(), "sftp", argv...)
-	command.Env = mnemonic.ChildEnv()
+	command.Env = childEnv()
 	command.Stdin = strings.NewReader(strings.Join(batch, "\n") + "\n")
 	command.Stdout = &said
 	command.Stderr = &said

internal/cli/ssh/ssh.go

@@ -3,10 +3,13 @@ package ssh
 
 import (
 	"fmt"
+	"os"
+	"strings"
 
 	"github.com/spf13/cobra"
 	"sneak.berlin/go/keyfunc/internal/cli/options"
 	"sneak.berlin/go/keyfunc/internal/derive"
+	"sneak.berlin/go/keyfunc/internal/mnemonic"
 	"sneak.berlin/go/keyfunc/internal/sshkey"
 )
 
@@ -84,6 +87,26 @@ func write(cmd *cobra.Command, text string) error {
 	return nil
 }
 
+// childEnv is the tool's environment with the mnemonic variables taken
+// out, for the ssh and sftp children it starts. "ssh to" exists so the
+// private key never leaves the tool; the mnemonic, from either variable,
+// must not leave it either.
+func childEnv() []string {
+	environ := os.Environ()
+	kept := make([]string, 0, len(environ))
+
+	for _, entry := range environ {
+		name, _, _ := strings.Cut(entry, "=")
+		if name == mnemonic.Variable || name == mnemonic.CommandVariable {
+			continue
+		}
+
+		kept = append(kept, entry)
+	}
+
+	return kept
+}
+
 // addComment gives a command its comment flag.
 func addComment(cmd *cobra.Command) {
 	cmd.Flags().String(

internal/cli/ssh/to.go

@@ -11,7 +11,6 @@ import (
 
 	"github.com/spf13/cobra"
 	"sneak.berlin/go/keyfunc/internal/cli/signals"
-	"sneak.berlin/go/keyfunc/internal/mnemonic"
 )
 
 // StatusError says the tool should end with the status ssh ended with.
@@ -80,7 +79,7 @@ func to() *cobra.Command {
 func connect(ctx context.Context, argv []string) error {
 	//nolint:gosec // the arguments are the user's own, meant for ssh
 	command := exec.CommandContext(ctx, "ssh", argv...)
-	command.Env = mnemonic.ChildEnv()
+	command.Env = childEnv()
 	command.Stdin = os.Stdin
 	command.Stdout = os.Stdout
 	command.Stderr = os.Stderr

internal/mnemonic/mnemonic.go

@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"os"
 	"os/exec"
-	"slices"
 	"strings"
 
 	"golang.org/x/term"
@@ -30,28 +29,6 @@ var ErrMissing = errors.New(
 	"no mnemonic given and standard input is not a terminal",
 )
 
-// The lengths a BIP-39 mnemonic may have.
-const (
-	twelve     = 12
-	fifteen    = 15
-	eighteen   = 18
-	twentyOne  = 21
-	twentyFour = 24
-)
-
-// ErrEmpty is returned for a mnemonic with no words in it, such as the
-// output of a mnemonic command that printed nothing.
-var ErrEmpty = errors.New("the mnemonic is empty")
-
-// ErrWordCount is returned for a mnemonic with a number of words that
-// BIP-39 does not allow.
-var ErrWordCount = errors.New("a mnemonic has 12, 15, 18, 21 or 24 words")
-
-// ErrUnknownWord is returned for a mnemonic with a word that is not on
-// the BIP-39 English word list. The error gives the word's position,
-// never the word, so the mnemonic stays out of the message.
-var ErrUnknownWord = errors.New("not on the BIP-39 word list")
-
 // ErrChecksum is returned for a mnemonic that fails the BIP-39
 // checksum.
 var ErrChecksum = errors.New("the mnemonic fails its BIP-39 checksum")
@@ -86,7 +63,6 @@ func Read(ctx context.Context, command string) (string, error) {
 func run(ctx context.Context, command string) (string, error) {
 	//nolint:gosec // running the user's own command is the point
 	shell := exec.CommandContext(ctx, "sh", "-c", command)
-	shell.Env = ChildEnv()
 
 	var complaint bytes.Buffer
 
@@ -107,25 +83,6 @@ func run(ctx context.Context, command string) (string, error) {
 	return string(out), nil
 }
 
-// ChildEnv is the tool's environment with the mnemonic variables taken
-// out, for the programs the tool starts: the mnemonic command, ssh and
-// sftp. The mnemonic, from either variable, never leaves the tool.
-func ChildEnv() []string {
-	environ := os.Environ()
-	kept := make([]string, 0, len(environ))
-
-	for _, entry := range environ {
-		name, _, _ := strings.Cut(entry, "=")
-		if name == Variable || name == CommandVariable {
-			continue
-		}
-
-		kept = append(kept, entry)
-	}
-
-	return kept
-}
-
 // ask prompts on the terminal with echo turned off.
 func ask() (string, error) {
 	fd := int(os.Stdin.Fd())
@@ -149,34 +106,13 @@ func ask() (string, error) {
 
 // checked joins the words with single spaces, whatever whitespace
 // separated them, since the seed is computed over the string itself,
-// and refuses a mnemonic that is not a valid BIP-39 mnemonic, with an
+// and refuses a mnemonic that does not pass the BIP-39 checksum.
-// error that says what is wrong with it.
+func checked(words string) (string, error) {
-func checked(text string) (string, error) {
+	words = strings.Join(strings.Fields(words), " ")
-	words := strings.Fields(text)
 
-	switch len(words) {
+	if !bip39.IsMnemonicValid(words) {
-	case 0:
-		return "", ErrEmpty
-	case twelve, fifteen, eighteen, twentyOne, twentyFour:
-	default:
-		return "", fmt.Errorf("%w, not %d", ErrWordCount, len(words))
-	}
-
-	wordList := bip39.English()
-
-	for i, word := range words {
-		if !slices.Contains(wordList, word) {
-			return "", fmt.Errorf(
-				"word %d of the mnemonic is %w", i+1, ErrUnknownWord,
-			)
-		}
-	}
-
-	joined := strings.Join(words, " ")
-
-	if !bip39.IsMnemonicValid(joined) {
 		return "", ErrChecksum
 	}
 
-	return joined, nil
+	return words, nil
 }

internal/mnemonic/mnemonic_test.go

@@ -1,8 +1,6 @@
 package mnemonic_test
 
 import (
-	"os"
-	"path/filepath"
 	"strings"
 	"testing"
 
@@ -63,31 +61,6 @@ func TestTheMnemonicInTheEnvironmentComesLast(t *testing.T) {
 	require.Equal(t, fromVariable, words)
 }
 
-func TestTheMnemonicIsNotHandedToTheCommand(t *testing.T) {
-	const marker = "KEYFUNC_TEST_MARKER"
-
-	t.Setenv(mnemonic.CommandVariable, prints(fromCommandVariable))
-	t.Setenv(mnemonic.Variable, fromVariable)
-	t.Setenv(marker, "reaches the command")
-
-	path := filepath.Join(t.TempDir(), "environment")
-
-	words, err := mnemonic.Read(
-		t.Context(), "env > '"+path+"'; "+prints(example()),
-	)
-	require.NoError(t, err)
-	require.Equal(t, example(), words)
-
-	//nolint:gosec // the path is a temporary file of the test's own
-	content, err := os.ReadFile(path)
-	require.NoError(t, err)
-
-	environment := string(content)
-	require.NotContains(t, environment, mnemonic.Variable+"=")
-	require.NotContains(t, environment, mnemonic.CommandVariable+"=")
-	require.Contains(t, environment, marker+"=")
-}
-
 func TestAFailingCommandSaysWhatWentWrong(t *testing.T) {
 	t.Setenv(mnemonic.CommandVariable, "")
 	t.Setenv(mnemonic.Variable, "")
@@ -105,38 +78,6 @@ func TestABadChecksumIsRefused(t *testing.T) {
 	require.ErrorIs(t, err, mnemonic.ErrChecksum)
 }
 
-func TestACommandThatPrintsNothingGivesAnEmptyMnemonic(t *testing.T) {
-	t.Setenv(mnemonic.CommandVariable, "")
-	t.Setenv(mnemonic.Variable, "")
-
-	_, err := mnemonic.Read(t.Context(), "true")
-	require.ErrorIs(t, err, mnemonic.ErrEmpty)
-	require.NotContains(t, err.Error(), "checksum")
-}
-
-func TestAWrongWordCountIsRefused(t *testing.T) {
-	t.Setenv(mnemonic.CommandVariable, "")
-	t.Setenv(mnemonic.Variable, strings.Repeat("abandon ", 3))
-
-	_, err := mnemonic.Read(t.Context(), "")
-	require.ErrorIs(t, err, mnemonic.ErrWordCount)
-	require.ErrorContains(t, err, "not 3")
-	require.NotContains(t, err.Error(), "checksum")
-}
-
-func TestAWordNotOnTheListIsNamedByPositionOnly(t *testing.T) {
-	const typo = "abuot"
-
-	t.Setenv(mnemonic.CommandVariable, "")
-	t.Setenv(mnemonic.Variable, strings.Repeat("abandon ", 11)+typo)
-
-	_, err := mnemonic.Read(t.Context(), "")
-	require.ErrorIs(t, err, mnemonic.ErrUnknownWord)
-	require.ErrorContains(t, err, "word 12 ")
-	require.NotContains(t, err.Error(), typo)
-	require.NotContains(t, err.Error(), "checksum")
-}
-
 func TestNothingToReadAndNobodyToAsk(t *testing.T) {
 	t.Setenv(mnemonic.CommandVariable, "")
 	t.Setenv(mnemonic.Variable, "")