private void ensureSigningKeyExists(final String signingSecretKey, final int signingKeySize) {
        var signingKeyToUse = signingSecretKey;
        if (StringUtils.isBlank(signingKeyToUse)) {
            LOGGER.warn("Secret key for signing is not defined under [{}]. CAS will attempt to auto-generate the signing key",
                getSigningKeySetting());
            signingKeyToUse = generateOctetJsonWebKeyOfSize(signingKeySize);
            val prop = String.format("%s=%s", getSigningKeySetting(), signingKeyToUse);
            issueWarningToAddKeyToSettings("signing", signingKeySize, signingKeyToUse, prop);
        }
        configureSigningKey(signingKeyToUse);
    }
Secret key IV algorithm. Default is {@code AES}.
core/cas-server-core-util-api/src/main/java/org/apereo/cas/util/cipher/BaseBinaryCipherExecutor.java