lcobucci/jwt · error · Lcobucci\JWT\Signer\Ecdsa\ConversionFailed

Invalid data. Should contain an integer.

Error message

Invalid data. Should contain an integer.

What it means

Thrown by the private readAsn1Integer helper when, while parsing a DER ECDSA signature inside fromAsn1, the next byte is not the ASN.1 INTEGER tag (0x02). A valid DER signature is a SEQUENCE of exactly two INTEGERs (r and s); anything else means the data is malformed.

Solutions

1. Verify the input is a DER ECDSA signature (SEQUENCE of two INTEGERs), not another DER structure
2. Check the signature was not truncated or modified in transit
3. Confirm you are not passing a certificate or public key where a signature is expected
4. Regenerate the signature from the original signer

Example fix

// before
$raw = $converter->fromAsn1($derPublicKeyPemBody, 32); // wrong input
// after
$raw = $converter->fromAsn1($derSignature, 32);

try { $raw = $converter->fromAsn1($der, $length); } catch (\Jose\Component\Signature\Exception\ConversionFailed $e) { return false; /* invalid signature input */ }

When it happens

Trigger: Calling fromAsn1() with a DER blob whose SEQUENCE contents are not two INTEGER elements — e.g. corrupted data, wrong ASN.1 structure (e.g. a certificate or public key passed instead of a signature), or data truncated mid-sequence.

Common situations: Passing a DER public key or certificate instead of a DER signature, manually crafted ASN.1 payloads, or a bit-flip corruption during transmission.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Invalid data. Should start with a sequence.
• Invalid signature length.
• The type of the provided key is not
• The length of the provided key is different than
• The curve of the provided key is not

AI-assisted analysis of lcobucci/jwt@375813049c (2026-09-14). Data as JSON: /api/errors/c9f780cd8b50a726. Report an issue: GitHub.

Appendix: source

Thrown at src/Signer/Ecdsa/MultibyteStringConverter.php:129

        $points = hex2bin(str_pad($pointR, $length, '0', STR_PAD_LEFT) . str_pad($pointS, $length, '0', STR_PAD_LEFT));
        assert(is_string($points));
        assert($points !== '');

        return $points;
    }

    private static function readAsn1Content(string $message, int &$position, int $length): string
    {
        $content   = substr($message, $position, $length);
        $position += $length;

        return $content;
    }

    private static function readAsn1Integer(string $message, int &$position): string
    {
        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_INTEGER) {
            throw ConversionFailed::integerExpected();
        }

        $length = (int) hexdec(self::readAsn1Content($message, $position, self::BYTE_SIZE));

        return self::readAsn1Content($message, $position, $length * self::BYTE_SIZE);
    }

    private static function retrievePositiveInteger(string $data): string
    {
        while (
            substr($data, 0, self::BYTE_SIZE) === self::ASN1_NEGATIVE_INTEGER
            && substr($data, 2, self::BYTE_SIZE) > self::ASN1_BIG_INTEGER_LIMIT
        ) {
            $data = substr($data, 2, null);
        }

        return $data;
    }

View on GitHub (pinned to 375813049c)