public static void enableAuth(HttpClient client, Keychain keychain, KeyId keyId) {
    Signer signer = new Signer(keychain, keyId);
    CredentialsProvider credProvider =
        (CredentialsProvider) client.getParams()
                .getParameter(CredentialsProvider.PROVIDER);

    CredentialsProvider newProvider;
    if (credProvider instanceof SignerCredentialsProvider) {
        newProvider = new SignerCredentialsProvider(signer,
                                                    ((SignerCredentialsProvider) credProvider).getDelegatee());
    } else {
        newProvider = new SignerCredentialsProvider(signer, credProvider);
    }

    client.getParams().setParameter(CredentialsProvider.PROVIDER, newProvider);
    AuthPolicy.registerAuthScheme(Constants.SCHEME, Http3SignatureAuthScheme.class);
    List<String> schemes = new ArrayList<String>();
    schemes.add(Constants.SCHEME);

    Collection authSchemePriority = (Collection) DefaultHttpParams.getDefaultParams().getParameter(AuthPolicy.AUTH_SCHEME_PRIORITY);
    if (authSchemePriority != null) {
        schemes.addAll(authSchemePriority);
    }
    client.getParams().setParameter(AuthPolicy.AUTH_SCHEME_PRIORITY, schemes);
}
 

private Credentials promptForCredentials(
    final AuthScheme authScheme,
    final HttpParams params, 
    final AuthScope authscope)
{
    LOG.debug("Credentials required");
    Credentials creds = null;
    CredentialsProvider credProvider = 
        (CredentialsProvider)params.getParameter(CredentialsProvider.PROVIDER);
    if (credProvider != null) {
        try {
            creds = credProvider.getCredentials(
                authScheme, authscope.getHost(), authscope.getPort(), false);
        } catch (CredentialsNotAvailableException e) {
            LOG.warn(e.getMessage());
        }
        if (creds != null) {
            this.state.setCredentials(authscope, creds);
            if (LOG.isDebugEnabled()) {
                LOG.debug(authscope + " new credentials given");
            }
        }
    } else {
        LOG.debug("Credentials provider not available");
    }
    return creds;
}
 

private Credentials promptForProxyCredentials(
    final AuthScheme authScheme,
    final HttpParams params,
    final AuthScope authscope) 
{
    LOG.debug("Proxy credentials required");
    Credentials creds = null;
    CredentialsProvider credProvider = 
        (CredentialsProvider)params.getParameter(CredentialsProvider.PROVIDER);
    if (credProvider != null) {
        try {
            creds = credProvider.getCredentials(
                authScheme, authscope.getHost(), authscope.getPort(), true);
        } catch (CredentialsNotAvailableException e) {
            LOG.warn(e.getMessage());
        }
        if (creds != null) {
            this.state.setProxyCredentials(authscope, creds);
            if (LOG.isDebugEnabled()) {
                LOG.debug(authscope + " new credentials given");
            }
        }
    } else {
        LOG.debug("Proxy credentials provider not available");
    }
    return creds;
}
 

private Credentials promptForCredentials(
    final AuthScheme authScheme,
    final HttpParams params, 
    final AuthScope authscope)
{
    LOG.debug("Credentials required");
    Credentials creds = null;
    CredentialsProvider credProvider = 
        (CredentialsProvider)params.getParameter(CredentialsProvider.PROVIDER);
    if (credProvider != null) {
        try {
            creds = credProvider.getCredentials(
                authScheme, authscope.getHost(), authscope.getPort(), false);
        } catch (CredentialsNotAvailableException e) {
            LOG.warn(e.getMessage());
        }
        if (creds != null) {
            this.state.setCredentials(authscope, creds);
            if (LOG.isDebugEnabled()) {
                LOG.debug(authscope + " new credentials given");
            }
        }
    } else {
        LOG.debug("Credentials provider not available");
    }
    return creds;
}
 

private Credentials promptForProxyCredentials(
    final AuthScheme authScheme,
    final HttpParams params,
    final AuthScope authscope) 
{
    LOG.debug("Proxy credentials required");
    Credentials creds = null;
    CredentialsProvider credProvider = 
        (CredentialsProvider)params.getParameter(CredentialsProvider.PROVIDER);
    if (credProvider != null) {
        try {
            creds = credProvider.getCredentials(
                authScheme, authscope.getHost(), authscope.getPort(), true);
        } catch (CredentialsNotAvailableException e) {
            LOG.warn(e.getMessage());
        }
        if (creds != null) {
            this.state.setProxyCredentials(authscope, creds);
            if (LOG.isDebugEnabled()) {
                LOG.debug(authscope + " new credentials given");
            }
        }
    } else {
        LOG.debug("Proxy credentials provider not available");
    }
    return creds;
}
 

public SignerCredentialsProvider(Signer signer, CredentialsProvider delegatee) {
    this.signer = signer;
    this.delegatee = delegatee;
}
 

public CredentialsProvider getDelegatee() {
    return delegatee;
}