diff --git a/identity/1.0/IWritableIdentityCredential.hal b/identity/1.0/IWritableIdentityCredential.hal
new file mode 100644
index 0000000..b1ce00d
--- /dev/null
+++ b/identity/1.0/IWritableIdentityCredential.hal
@@ -0,0 +1,236 @@
+/*
+ * Copyright 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.identity@1.0;
+
+/**
+ * IWritableIdentityCredential is used to personalize a new identity credential.  Credentials cannot
+ * be updated or modified after creation; any changes require deletion and re-creation.
+ */
+interface IWritableIdentityCredential {
+    /**
+     * Gets the certificate chain for credentialKey which can be used to prove the hardware
+     * characteristics to an issuing authority.  Must not be called more than once.
+     *
+     * The certificate chain must be generated using Keymaster Attestation
+     * (see https://source.android.com/security/keystore/attestation) and must also
+     * have the Tag::IDENTITY_CREDENTIAL_KEY tag from KeyMaster 4.1 set. This tag indicates
+     * that this key is an Identity Credential key (which can only sign/MAC very
+     * specific messages) and not an Android Keystore key (which can be used to sign/MAC
+     * anything).
+     *
+     * @param attestationChallenge a challenge set by the issuer to ensure freshness.
+     *
+     * @return result is OK on success, FAILED if an error occurred.
+     *
+     * @return certificate is the X.509 certificate chain for the credentialKey
+     */
+    getAttestationCertificate(vec<uint8_t> attestationChallenge)
+        generates(Result result, vec<uint8_t> certificate);
+
+    /**
+     * Start the personalization process.
+     *
+     * startPersonalization must not be called more than once.
+     *
+     * @param accessControlProfileCount specifies the number of access control profiles that will be
+     *     provisioned with addAccessControlProfile().
+     *
+     * @param entryCounts specifies the number of data entries that will be provisioned with
+     *     beginAddEntry() and addEntry(). Each item in the array specifies how many entries
+     *     will be added for each name space.
+     *
+     * @return result is OK on success, FAILED if an error occurred.
+     *
+     */
+    startPersonalization(uint16_t accessControlProfileCount, vec<uint16_t> entryCounts)
+        generates(Result result);
+
+    /**
+     * Add an access control profile, which defines the requirements or retrieval of one or more
+     * entries.  If both readerCertificate and userAuthenticationRequired are empty/false,
+     * associated entries are open access, requiring no authentication to read (though the caller
+     * is free to require other authentication above this HAL).
+     *
+     * This method must be called exactly as many times as specified in the startPersonalization()
+     * accessControlProfileCount parameter. If this is requirement is not met, the method fails
+     * with INVALID_DATA.
+     *
+     * @param id a numeric identifier that must be unique within the context of a Credential and may
+     *     be used to reference the profile. If this is not satisfied the call fails with
+     *     INVALID_DATA.
+     *
+     * @param readerCertificate if non-empty, specifies a X.509 certificate (or chain of certificates)
+     *     that must be used to authenticate requests (see the readerSignature parameter in
+     *     IIdentityCredential.startRetrieval).
+     *
+     * @param userAuthenticationRequired if true, specifies that the user is required to
+     *     authenticate to allow requests.  Required authentication freshness is specified by
+     *     timeout below.
+     *
+     * @param timeoutMillis specifies the amount of time, in milliseconds, for which a user
+     *     authentication (see userAuthenticationRequired above) is valid, if
+     *     userAuthenticationRequired is true. If the timout is zero then authentication is
+     *     required for each reader session. If userAuthenticationRequired is false, the timeout
+     *     must be zero. If this requirement is not met the call fails with INVALID_DATA.
+     *
+     * @param secureUserId must be non-zero if userAuthenticationRequired is true. It is not
+     *     related to any Android user ID or UID, but is created in the Gatekeeper application
+     *     in the secure environment. If this requirement is not met the call fails with
+     *     INVALID_DATA.
+     *
+     * @return result is OK on success, INVALID_DATA or FAILED if an error occurred.
+     *
+     * @return secureAccessControlProfile is a structure with the passed-in data and MAC created
+     *     with storageKey for authenticating the data at a later point in time.
+     */
+    addAccessControlProfile(uint16_t id, vec<uint8_t> readerCertificate,
+                            bool userAuthenticationRequired, uint64_t timeoutMillis,
+                            uint64_t secureUserId)
+        generates(Result result, SecureAccessControlProfile secureAccessControlProfile);
+
+    /**
+     * Begins the process of adding an entry to the credential.  All access control profiles must be
+     * added before calling this method.  Entries must be added in namespace "groups", meaning all
+     * entries of one namespace must be added before adding entries from another namespace.
+     *
+     * This method must be called exactly as many times as the sum of the items in the entryCounts
+     * parameter specified in the startPersonalization(), and must be followed by one or more calls
+     * to addEntryValue(). If this requirement is not met the method fails with INVALID_DATA.
+     *
+     * @param accessControlProfileIds specifies the set of access control profiles that can
+     *     authorize access to the provisioned element.
+     *
+     * @param nameSpace is the namespace of the element, e.g. "org.iso.18013"
+     *
+     * @param name is the name of the element.
+     *
+     * @param entrySize is the size of the entry value. If this requirement
+     *     is not met this method fails with INVALID_DATA.
+     *
+     * @return result is OK on success, INVALID_DATA or FAILED if an error occurred.
+     */
+    beginAddEntry(vec<uint16_t> accessControlProfileIds, string nameSpace,
+                  string name, uint32_t entrySize)
+        generates(Result result);
+
+    /**
+     * Continues the process of adding an entry, providing a value or part of a value.
+     *
+     * In the common case, this method will be called only once per entry added.  In the case of
+     * values that are larger than the secure environment's GCM chunk size
+     * (see IIdentityCredentialStore.getHardwareInformation()), the caller must provide the
+     * value in chunks.  All chunks must be exactly gcmChunkSize except the last and the sum of all
+     * chunk sizes must equal the value of the beginAddEntry() entrySize argument. If this
+     * requirement is not met the call fails with INVALID_DATA.
+     *
+     * @param content is the entry value, encoded as CBOR. In the case the content exceeds gcmChunkSize,
+     *     this may be partial content up to gcmChunkSize bytes long.
+     *
+     * @return result is OK on success, INVALID_DATA or FAILED if an error occurred.
+     *
+     * @return encryptedContent contains the encrypted and MACed content.  For directly-available
+     *     credentials the contents are implementation-defined but must not exceed 32 bytes in
+     *     length.
+     *
+     *     For other credentials, encryptedContent contains:
+     *
+     *         AES-GCM-ENC(storageKey, R, Data, AdditionalData)
+     *
+     *     where:
+     *
+     *         Data = any   ; value
+     *
+     *         AdditionalData = {
+     *             "Namespace" : tstr,
+     *             "Name" : tstr,
+     *             "AccessControlProfileIds" : [ + uint ],
+     *         }
+     */
+    addEntryValue(vec<uint8_t> content)
+        generates(Result result, vec<uint8_t> encryptedContent);
+
+    /**
+     * Finishes adding entries and returns a signature that an issuing authority may use to validate
+     * that all data was provisioned correctly.
+     *
+     * After this method is called, the IWritableIdentityCredential is no longer usable.
+     *
+     * @return result is OK on success or FAILED if an error occurred.
+     *
+     * @return credentialData is a CBOR-encoded structure (in CDDL notation):
+     *
+     *         CredentialData = [
+     *              tstr,   ; docType, an optional name that identifies the type of credential
+     *              bool,   ; testCredential, indicates if this is a test credential
+     *              bstr    ; an opaque byte vector with encrypted data, see below
+     *         ]
+     *
+     *     The last element is an opaque byte vector which contains encrypted copies of the
+     *     secrets used to secure the new credential's data and to authenticate the credential to
+     *     the issuing authority.  It contains:
+     *
+     *         AES-GCM-ENC(HBK, R, CredentialKeys, docType)
+     *
+     *     where HBK is a unique hardware-bound key that has never existed outside of the secure
+     *     environment (except it's all zeroes if testCredential is True) and CredentialKeys is
+     *     the CBOR-encoded structure (in CDDL notation):
+     *
+     *         CredentialKeys = [
+     *              bstr,   ; storageKey, a 128-bit AES key
+     *              bstr    ; credentialPrivKey, the private key for credentialKey
+     *         ]
+     *
+     * @return proofOfProvisioningSignature proves to the IA that the credential was imported into the
+     *     secure hardware without alteration or error.  When the final addEntry() call is made
+     *     (when the number of provisioned entries equals the sum of the items in
+     *     startPersonalization() entryCounts parameter), it a COSE_Sign1 structure
+     *     signed by CredentialKey with payload set to the ProofOfProvisioning CBOR below:
+     *
+     *          ProofOfProvisioning = [
+     *              "ProofOfProvisioning",
+     *              tstr,                         ; DocType
+     *              [ * AccessControlProfile ],
+     *              ProvisionedData,
+     *              bool                          ; true if this is a test credential, should
+     *                                            ; always be false.
+     *          ]
+     *
+     *          AccessControlProfile = {
+     *              "id" : uint,
+     *              ? "readerCertificate" : bstr,
+     *              ? (
+     *                  "userAuthenticationRequired" : bool,
+     *                  "timeoutMillis" : uint,
+     *              )
+     *          }
+     *
+     *          ProvisionedData = {
+     *              * Namespace => [ + Entry ]
+     *          },
+     *
+     *          Namespace = tstr
+     *
+     *          Entry = {
+     *              "name" : tstr,
+     *              "value" : any,
+     *              "accessControlProfiles" : [ * uint ],
+     *          }
+     */
+    finishAddingEntries()
+        generates(Result result, vec<uint8_t> credentialData,
+                  vec<uint8_t> proofOfProvisioningSignature);
+};