docs/html/training/articles/keystore.jd

page.title=Android Keystore System
@jd:body

<div id="qv-wrapper">
  <div id="qv">
    <h2>In this document</h2>
    <ol>
      <li><a href="#WhichShouldIUse">Choosing Between a Keychain or the Android Keystore Provider</a></li>
      <li><a href="#UsingAndroidKeyStore">Using Android Keystore Provider
      </a></li>
      <ol>
        <li><a href="#GeneratingANewPrivateKey">Generating a New Private Key</a></li>
        <li><a href="#WorkingWithKeyStoreEntries">Working with Keystore Entries</a></li>
        <li><a href="#ListingEntries">Listing Entries</a></li>
        <li><a href="#SigningAndVerifyingData">Signing and Verifying Data</a></li>
      </ol>
    </ol>

    <h2>Blog articles</h2>
    <ol>
      <li><a
        href="http://android-developers.blogspot.com/2012/03/unifying-key-store-access-in-ics.html">
          <h4>Unifying Key Store Access in ICS</h4>
      </a></li>
    </ol>
  </div>
</div>

<p>The Android Keystore system lets you store private keys
  in a container to make it more difficult to extract from the
  device. Once keys are in the keystore, they can be used for
  cryptographic operations with the private key material remaining
  non-exportable.</p>

<p>The Keystore system is used by the {@link
  android.security.KeyChain} API as well as the Android
  Keystore provider feature that was introduced in Android 4.3
  (API level 18). This document goes over when and how to use the
  Android Keystore provider.</p>

<h2 id="WhichShouldIUse">Choosing Between a Keychain or the
Android Keystore Provider</h2>

<p>Use the {@link android.security.KeyChain} API when you want
  system-wide credentials. When an app requests the use of any credential
  through the {@link android.security.KeyChain} API, users get to
  choose, through a system-provided UI, which of the installed credentials
  an app can access. This allows several apps to use the
  same set of credentials with user consent.</p>

<p>Use the Android Keystore provider to let an individual app store its own
  credentials that only the app itself can access.
  This provides a way for apps to manage credentials that are usable
  only by itself while providing the same security benefits that the
  {@link android.security.KeyChain} API provides for system-wide
  credentials. This method requires no user interaction to select the credentials.</p>

<h2 id="UsingAndroidKeyStore">Using Android Keystore Provider</h2>

<p>
To use this feature, you use the standard {@link java.security.KeyStore}
and {@link java.security.KeyPairGenerator} classes along with the
{@code AndroidKeyStore} provider introduced in Android 4.3 (API level 18).</p>

<p>{@code AndroidKeyStore} is registered as a {@link
  java.security.KeyStore} type for use with the {@link
  java.security.KeyStore#getInstance(String) KeyStore.getInstance(type)}
  method and as a provider for use with the {@link
  java.security.KeyPairGenerator#getInstance(String, String)
  KeyPairGenerator.getInstance(algorithm, provider)} method.</p>

<h3 id="GeneratingANewPrivateKey">Generating a New Private Key</h3>

<p>Generating a new {@link java.security.PrivateKey} requires that
  you also specify the initial X.509 attributes that the self-signed
  certificate will have. You can replace the certificate at a later
  time with a certificate signed by a Certificate Authority.</p>

<p>To generate the key, use a {@link java.security.KeyPairGenerator}
  with {@link android.security.KeyPairGeneratorSpec}:</p>

{@sample development/samples/ApiDemos/src/com/example/android/apis/security/KeyStoreUsage.java generate}

<h3 id="WorkingWithKeyStoreEntries">Working with Keystore Entries</h3>

<p>Using the {@code AndroidKeyStore} provider takes place through
  all the standard {@link java.security.KeyStore} APIs.</p>

<h4 id="ListingEntries">Listing Entries</h4>

<p>List entries in the keystore by calling the {@link
  java.security.KeyStore#aliases()} method:</p>

{@sample development/samples/ApiDemos/src/com/example/android/apis/security/KeyStoreUsage.java list}

<h4 id="SigningAndVerifyingData">Signing and Verifying Data</h4>

<p>Sign data by fetching the {@link
  java.security.KeyStore.Entry} from the keystore and using the
  {@link java.security.Signature} APIs, such as {@link
  java.security.Signature#sign()}:</p>

{@sample development/samples/ApiDemos/src/com/example/android/apis/security/KeyStoreUsage.java sign}

<p>Similarly, verify data with the {@link java.security.Signature#verify(byte[])} method:</p>

{@sample development/samples/ApiDemos/src/com/example/android/apis/security/KeyStoreUsage.java verify}