TheAlgorithms/Go · error

ErrNoTextToEncrypt

ErrNoTextToEncrypt

Error message

%w: cannot encrypt a text, %q, ending with the placeholder char %q

What it means

Encrypt pads text with a placeholder rune; input that already ends with that placeholder would make correct unpadding ambiguous on decrypt, so Encrypt refuses it, wrapping ErrNoTextToEncrypt with the text and placeholder shown.

Solutions

1. Strip or escape the placeholder character from the plaintext before encrypting
2. Choose a placeholder guaranteed absent from your plaintext alphabet
3. Detect via errors.Is(err, ErrNoTextToEncrypt) and sanitize then retry

When it happens

Trigger: Thrown at cipher/transposition/transposition.go:64 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/e2125b418c23b132. Report an issue: GitHub.

Appendix: source

Thrown at cipher/transposition/transposition.go:64

		if wordSet[i] == subString {
			return i
		}
	}
	return 0
}

func Encrypt(text []rune, keyWord string) ([]rune, error) {
	key := getKey(keyWord)
	keyLength := len(key)
	textLength := len(text)
	if keyLength <= 0 {
		return nil, ErrKeyMissing
	}
	if textLength <= 0 {
		return nil, ErrNoTextToEncrypt
	}
	if text[len(text)-1] == placeholder {
		return nil, fmt.Errorf("%w: cannot encrypt a text, %q, ending with the placeholder char %q", ErrNoTextToEncrypt, text, placeholder)
	}
	n := textLength % keyLength

	for i := 0; i < keyLength-n; i++ {
		text = append(text, placeholder)
	}
	textLength = len(text)
	var result []rune
	for i := 0; i < textLength; i += keyLength {
		transposition := make([]rune, keyLength)
		for j := 0; j < keyLength; j++ {
			transposition[key[j]-1] = text[i+j]
		}
		result = append(result, transposition...)
	}
	return result, nil
}

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