TheAlgorithms/Go · error

failed encipher

Error message

failed encipher: %w

What it means

Polybius.Encrypt wraps a per-character encipher failure (usually the character not present in the key) with fmt.Errorf %w, aborting the whole message and preserving the underlying error for errors.Is/As.

Solutions

1. Unwrap with errors.Unwrap or errors.Is to reach the underlying cause
2. Filter or map unsupported characters before encrypting
3. Encrypt character-by-character to isolate and skip bad symbols

When it happens

Trigger: Thrown at cipher/polybius/polybius.go:57 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of TheAlgorithms/Go@5ba447ec5f (2026-09-02). Data as JSON: /api/errors/b06adafa48371881. Report an issue: GitHub.

Appendix: source

Thrown at cipher/polybius/polybius.go:57

	for i, r := range chars {
		if strings.ContainsRune(chars[i+1:], r) {
			return nil, fmt.Errorf("%q contains same character %q", chars[i+1:], r)
		}
	}

	if len(key) != size*size {
		return nil, fmt.Errorf("len(key): %d must be as long as size squared: %d", len(key), size*size)
	}
	return &Polybius{size, chars, key}, nil
}

// Encrypt encrypts with polybius encryption
func (p *Polybius) Encrypt(text string) (string, error) {
	encryptedText := ""
	for _, char := range strings.ToUpper(text) {
		encryptedChar, err := p.encipher(char)
		if err != nil {
			return "", fmt.Errorf("failed encipher: %w", err)
		}
		encryptedText += encryptedChar
	}
	return encryptedText, nil
}

// Decrypt decrypts with polybius encryption
func (p *Polybius) Decrypt(text string) (string, error) {
	chars := []rune(strings.ToUpper(text))
	decryptedText := ""
	for i := 0; i < len(chars); i += 2 {
		decryptedChar, err := p.decipher(chars[i:int(math.Min(float64(i+2), float64(len(chars))))])
		if err != nil {
			return "", fmt.Errorf("failed decipher: %w", err)
		}
		decryptedText += decryptedChar
	}
	return decryptedText, nil

View on GitHub (pinned to 5ba447ec5f)