t8y2/dbx · error

verify Kerberos SASL security-layer challenge: %w

Error message

verify Kerberos SASL security-layer challenge: %w

What it means

Returned by securityLayerResponse when the SASL security-layer challenge WrapToken decodes but fails cryptographic verification with the negotiated Kerberos session key (keyusage GSSAPI_ACCEPTOR_SEAL). This typically means the session key differs on the two sides — e.g. mismatched enctypes, tickets from different KDCs, or corrupted token bytes.

Source

Thrown at agents/drivers/cassandra-go/kerberos.go:387

	}
	payload = append(payload, encodedRequest...)
	encodedOID, err := asn1.Marshal(gssapi.OIDKRB5.OID())
	if err != nil {
		return nil, err
	}
	header := append([]byte{kerberosGSSAPITag}, asn1tools.MarshalLengthBytes(len(encodedOID)+len(payload))...)
	header = append(header, encodedOID...)
	return append(header, payload...), nil
}

func (authenticator *kerberosAuthenticator) securityLayerResponse(challenge []byte) ([]byte, error) {
	var request gssapi.WrapToken
	if err := request.Unmarshal(challenge, true); err != nil {
		return nil, fmt.Errorf("decode Kerberos SASL security-layer challenge: %w", err)
	}
	valid, err := request.Verify(authenticator.sessionKey, keyusage.GSSAPI_ACCEPTOR_SEAL)
	if err != nil {
		return nil, fmt.Errorf("verify Kerberos SASL security-layer challenge: %w", err)
	}
	if !valid {
		return nil, fmt.Errorf("invalid Kerberos SASL security-layer challenge")
	}
	if len(request.Payload) < 4 || request.Payload[0]&kerberosSecurityNone == 0 {
		return nil, fmt.Errorf("Cassandra Kerberos server does not allow SASL QOP auth")
	}
	payload := []byte{kerberosSecurityNone, 0, 0, 0}
	payload = append(payload, authenticator.authorizationID...)
	response, err := gssapi.NewInitiatorWrapToken(payload, authenticator.sessionKey)
	if err != nil {
		return nil, err
	}
	return response.Marshal()
}

func kerberosAuthenticatorChecksum() []byte {
	checksum := make([]byte, 24)

View on GitHub (pinned to c0390bff16)

Solutions

1. Ensure agent and Cassandra server use the same KDC realm and enctypes (check permitted enctypes in krb5.conf)
2. Regenerate keytabs if keys were recently rotated
3. Verify clocks and KDC health so both sides derive the same session key
4. Confirm no intermediary is altering the SASL payload

When it happens

Trigger: Thrown at agents/drivers/cassandra-go/kerberos.go:387 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of t8y2/dbx@c0390bff16 (2026-09-05). Data as JSON: /api/errors/b833ef7804634aed. Report an issue: GitHub.