/**     * Determines if a kvno matches another kvno. Used in the method     * findKey(type, kvno, keys). Always returns true if either input     * is null or zero, in case any side does not have kvno info available.     *     * Note: zero is included because N/A is not a legal value for kvno     * in javax.security.auth.kerberos.KerberosKey. Therefore, the info     * that the kvno is N/A might be lost when converting between this     * class and KerberosKey.     */    private static boolean versionMatches(Integer v1, Integer v2) {        if (v1 == null || v1 == 0 || v2 == null || v2 == 0) {            return true;        }        return v1.equals(v2);    }     /**     * Find a key with given etype and kvno     * @param kvno if null, return any (first?) key     */    public static EncryptionKey findKey(int etype, Integer kvno, EncryptionKey[] keys)        throws KrbException {         // check if encryption type is supported        if (!EType.isSupported(etype)) {            throw new KrbException("Encryption type " +                EType.toString(etype) + " is not supported/enabled");        }         int ktype;        boolean etypeFound = false;        for (int i = 0; i < keys.length; i++) {            ktype = keys[i].getEType();            if (EType.isSupported(ktype)) {                Integer kv = keys[i].getKeyVersionNumber();                if (etype == ktype) {                    etypeFound = true;                    if (versionMatches(kvno, kv)) {                        return keys[i];                    }                }            }        }         // Key not found.        // allow DES key to be used for the DES etypes        if ((etype == EncryptedData.ETYPE_DES_CBC_CRC ||            etype == EncryptedData.ETYPE_DES_CBC_MD5)) {            for (int i = 0; i < keys.length; i++) {                ktype = keys[i].getEType();                if (ktype == EncryptedData.ETYPE_DES_CBC_CRC ||                        ktype == EncryptedData.ETYPE_DES_CBC_MD5) {                    Integer kv = keys[i].getKeyVersionNumber();                    etypeFound = true;                    if (versionMatches(kvno, kv)) {                        return new EncryptionKey(etype, keys[i].getBytes());                    }                }            }        }        if (etypeFound) {            throw new KrbException(Krb5.KRB_AP_ERR_BADKEYVER);        }        return null;    }}

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