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For devices running Android 13 or higher, Android
supports the Trust on First Use (TOFU) authentication approach
(RFC7435),
which lets users trust an enterprise (EAP) network by installing the root CA
used by the server and setting its domain name in a saved network. TOFU allows
the device to obtain an unauthenticated public key when a user first connects
to an enterprise network and retain the key for subsequent connections.
Background
Compared to personal networks that just require a password, enterprise networks
use public key infrastructure (PKI) authentication, which requires the client
to preinstall certificates. In Android 11 or lower, users can select the
Do not validate option for the server CA certificate in the network settings,
bypassing the validation of the server side certificate. However, to strengthen
security and comply with the WPA R2 specification, Android 12 introduced a
requirement for enterprise networks to have server certificate validation. This
additional requirement created a barrier for users as they need to install a CA
certificate for such networks. TOFU provides a way for users to connect to a
PKI-based enterprise network by simply accepting its root CA.
Feature behavior
Devices that support TOFU display the following behavior when a user connects
to an enterprise network that doesn't have an already-installed
authenticated public key.
Connect to new network through Wi-Fi picker
Select a new enterprise network in Wi-Fi picker.
The device displays a dialog (Figure 1) to confirm whether the
network is trusted.
Tap Yes, connect to accept the network connection, or tap No, don't
connect to decline.
If you tap Yes, connect, the device automatically configures the
security parameters, connects to the network, and enables autoconnect
for the network.
If you tap No, don't connect, the device disconnects from the
network and disables autoconnect for the network.
Figure 1. Dialog for the TOFU feature
Connect to existing network with autoconnect enabled
When connecting to an enterprise network that has autoconnect enabled but
doesn't have a valid CA certificate, the device connects automatically, then
displays a sticky (nondismissable) notification.
Tap the notification.
The device displays a dialog (Figure 1) to confirm whether the
network is trusted.
Tap Yes, connect to accept the network connection, or tap No, don't
connect to decline.
If you tap Yes, connect, the device automatically configures the
security parameters, connects to the network, and enables autoconnect
for the network.
If you tap No, don't connect, the device disconnects from the
network and disables autoconnect for the network.
To validate the implementation of TOFU on your device, use the following tests:
CTS: CtsWifiTestCases
VTS: VtsHalWifiSupplicantStaNetworkTargetTest
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Last updated 2025-08-29 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-29 UTC."],[],[],null,["# Trust on First Use (TOFU)\n\nFor devices running Android 13 or higher, Android\nsupports the Trust on First Use (TOFU) authentication approach\n([RFC7435](https://datatracker.ietf.org/doc/html/rfc7435.html)),\nwhich lets users trust an enterprise (EAP) network by installing the root CA\nused by the server and setting its domain name in a saved network. TOFU allows\nthe device to obtain an unauthenticated public key when a user first connects\nto an enterprise network and retain the key for subsequent connections.\n\nBackground\n----------\n\nCompared to personal networks that just require a password, enterprise networks\nuse public key infrastructure (PKI) authentication, which requires the client\nto preinstall certificates. In Android 11 or lower, users can select the\n*Do not validate* option for the server CA certificate in the network settings,\nbypassing the validation of the server side certificate. However, to strengthen\nsecurity and comply with the WPA R2 specification, Android 12 introduced a\nrequirement for enterprise networks to have server certificate validation. This\nadditional requirement created a barrier for users as they need to install a CA\ncertificate for such networks. TOFU provides a way for users to connect to a\nPKI-based enterprise network by simply accepting its root CA.\n\nFeature behavior\n----------------\n\nDevices that support TOFU display the following behavior when a user connects\nto an enterprise network that doesn't have an *already-installed*\nauthenticated public key.\n\n### Connect to new network through Wi-Fi picker\n\n1. Select a new enterprise network in Wi-Fi picker.\n\n The device displays a dialog (Figure 1) to confirm whether the\n network is trusted.\n2. Tap **Yes, connect** to accept the network connection, or tap **No, don't\n connect** to decline.\n\n - If you tap **Yes, connect**, the device automatically configures the\n security parameters, connects to the network, and enables autoconnect\n for the network.\n\n | **Note:** Misconfigured networks that use invalid or expired certificates might not allow any security validation by the device. In such cases, the device fails to connect to the network.\n - If you tap **No, don't connect**, the device disconnects from the\n network and disables autoconnect for the network.\n\n **Figure 1.** Dialog for the TOFU feature\n\n### Connect to existing network with autoconnect enabled\n\nWhen connecting to an enterprise network that has autoconnect enabled but\ndoesn't have a valid CA certificate, the device connects automatically, then\ndisplays a sticky (nondismissable) notification.\n\n1. Tap the notification.\n\n The device displays a dialog (Figure 1) to confirm whether the\n network is trusted.\n2. Tap **Yes, connect** to accept the network connection, or tap **No, don't\n connect** to decline.\n\n - If you tap **Yes, connect**, the device automatically configures the\n security parameters, connects to the network, and enables autoconnect\n for the network.\n\n | **Note:** Misconfigured networks that use invalid or expired certificates might not allow any security validation by the device. In such cases, the device fails to connect to the network.\n - If you tap **No, don't connect**, the device disconnects from the\n network and disables autoconnect for the network.\n\nImplementation\n--------------\n\nTo support the TOFU feature, implement the supplicant HALs provided in the\nAndroid Open Source Project (AOSP) at\n[`/hardware/interfaces/wifi/supplicant/aidl/android/hardware/wifi/supplicant`](https://cs.android.com/android/platform/superproject/+/android-latest-release:hardware/interfaces/wifi/supplicant/aidl/android/hardware/wifi/supplicant).\n\nThe following public APIs are available in Android 13\nfor use by apps:\n\n- [`WifiManager#isTrustOnFirstUseSupported()`](https://developer.android.com/reference/android/net/wifi/WifiManager#isTrustOnFirstUseSupported()): Indicates whether the device supports TOFU.\n- [`WifiEnterpriseConfig#enableTrustOnFirstUse(boolean)`](https://developer.android.com/reference/android/net/wifi/WifiEnterpriseConfig#enableTrustOnFirstUse(boolean)): Enables TOFU.\n- [`WifiEnterpriseConfig#isTrustOnFirstUseEnabled()`](https://developer.android.com/reference/android/net/wifi/WifiEnterpriseConfig#isTrustOnFirstUseEnabled()): Indicates whether TOFU is enabled.\n\nValidation\n----------\n\nTo validate the implementation of TOFU on your device, use the following tests:\n\n- CTS: `CtsWifiTestCases`\n- VTS: `VtsHalWifiSupplicantStaNetworkTargetTest`"]]
