Rename pwdToken to stretchedLskf
stretchedLskf is a much more self-explanatory name for what this value is: it's the result of passing the LSKF through a key stretching function (scrypt). The words "password" and "token" are already overloaded in this code, so this should reduce confusion. As usual I'll be updating http://go/android-locksettings-design accordingly. Test: atest com.android.server.locksettings Change-Id: Id57de2d1f9246b3aed09554841ecfb54c947582f
This commit is contained in:
Eric Biggers
@@ -144,7 +144,7 @@ public class SyntheticPasswordManager {
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private static final int PASSWORD_SCRYPT_LOG_R = 3;
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private static final int PASSWORD_SCRYPT_LOG_P = 1;
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private static final int PASSWORD_SALT_LENGTH = 16;
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private static final int PASSWORD_TOKEN_LENGTH = 32;
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private static final int STRETCHED_LSKF_LENGTH = 32;
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private static final String TAG = "SyntheticPasswordManager";
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private static final byte[] PERSONALIZATION_SECDISCARDABLE = "secdiscardable-transform".getBytes();
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@@ -772,7 +772,7 @@ public class SyntheticPasswordManager {
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LockscreenCredential credential, SyntheticPassword sp, int userId) {
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long protectorId = generateProtectorId();
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PasswordData pwd = PasswordData.create(credential.getType());
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byte[] pwdToken = computePasswordToken(credential, pwd);
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byte[] stretchedLskf = stretchLskf(credential, pwd);
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final long sid;
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final byte[] protectorSecret;
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@@ -780,7 +780,7 @@ public class SyntheticPasswordManager {
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// Protector uses Weaver to verify the LSKF
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int weaverSlot = getNextAvailableWeaverSlot();
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Slog.i(TAG, "Weaver enroll password to slot " + weaverSlot + " for user " + userId);
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byte[] weaverSecret = weaverEnroll(weaverSlot, passwordTokenToWeaverKey(pwdToken),
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byte[] weaverSecret = weaverEnroll(weaverSlot, stretchedLskfToWeaverKey(stretchedLskf),
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null);
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if (weaverSecret == null) {
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throw new IllegalStateException(
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@@ -793,7 +793,7 @@ public class SyntheticPasswordManager {
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pwd.passwordHandle = null;
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sid = GateKeeper.INVALID_SECURE_USER_ID;
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protectorSecret = transformUnderWeaverSecret(pwdToken, weaverSecret);
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protectorSecret = transformUnderWeaverSecret(stretchedLskf, weaverSecret);
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} else {
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// Protector uses Gatekeeper to verify the LSKF
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@@ -807,7 +807,7 @@ public class SyntheticPasswordManager {
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GateKeeperResponse response;
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try {
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response = gatekeeper.enroll(fakeUid(userId), null, null,
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passwordTokenToGkInput(pwdToken));
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stretchedLskfToGkPassword(stretchedLskf));
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} catch (RemoteException e) {
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throw new IllegalStateException("Failed to enroll LSKF for new SP protector for "
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+ "user " + userId, e);
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@@ -818,7 +818,7 @@ public class SyntheticPasswordManager {
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}
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pwd.passwordHandle = response.getPayload();
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sid = sidFromPasswordHandle(pwd.passwordHandle);
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protectorSecret = transformUnderSecdiscardable(pwdToken,
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protectorSecret = transformUnderSecdiscardable(stretchedLskf,
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createSecdiscardable(protectorId, userId));
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// No need to pass in quality since the credential type already encodes sufficient info
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synchronizeFrpPassword(pwd, 0, userId);
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@@ -836,12 +836,13 @@ public class SyntheticPasswordManager {
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PersistentData persistentData = mStorage.readPersistentDataBlock();
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if (persistentData.type == PersistentData.TYPE_SP) {
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PasswordData pwd = PasswordData.fromBytes(persistentData.payload);
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byte[] pwdToken = computePasswordToken(userCredential, pwd);
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byte[] stretchedLskf = stretchLskf(userCredential, pwd);
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GateKeeperResponse response;
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try {
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response = gatekeeper.verifyChallenge(fakeUid(persistentData.userId),
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0 /* challenge */, pwd.passwordHandle, passwordTokenToGkInput(pwdToken));
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0 /* challenge */, pwd.passwordHandle,
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stretchedLskfToGkPassword(stretchedLskf));
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} catch (RemoteException e) {
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Slog.e(TAG, "FRP verifyChallenge failed", e);
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return VerifyCredentialResponse.ERROR;
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@@ -853,10 +854,10 @@ public class SyntheticPasswordManager {
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return VerifyCredentialResponse.ERROR;
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}
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PasswordData pwd = PasswordData.fromBytes(persistentData.payload);
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byte[] pwdToken = computePasswordToken(userCredential, pwd);
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byte[] stretchedLskf = stretchLskf(userCredential, pwd);
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int weaverSlot = persistentData.userId;
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return weaverVerify(weaverSlot, passwordTokenToWeaverKey(pwdToken)).stripPayload();
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return weaverVerify(weaverSlot, stretchedLskfToWeaverKey(stretchedLskf)).stripPayload();
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} else {
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Slog.e(TAG, "persistentData.type must be TYPE_SP or TYPE_SP_WEAVER, but is "
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+ persistentData.type);
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@@ -1034,7 +1035,7 @@ public class SyntheticPasswordManager {
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return result;
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}
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byte[] pwdToken = computePasswordToken(credential, pwd);
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byte[] stretchedLskf = stretchLskf(credential, pwd);
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final byte[] protectorSecret;
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final long sid;
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@@ -1046,20 +1047,20 @@ public class SyntheticPasswordManager {
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result.gkResponse = VerifyCredentialResponse.ERROR;
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return result;
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}
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result.gkResponse = weaverVerify(weaverSlot, passwordTokenToWeaverKey(pwdToken));
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result.gkResponse = weaverVerify(weaverSlot, stretchedLskfToWeaverKey(stretchedLskf));
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if (result.gkResponse.getResponseCode() != VerifyCredentialResponse.RESPONSE_OK) {
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return result;
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}
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sid = GateKeeper.INVALID_SECURE_USER_ID;
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protectorSecret = transformUnderWeaverSecret(pwdToken,
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protectorSecret = transformUnderWeaverSecret(stretchedLskf,
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result.gkResponse.getGatekeeperHAT());
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} else {
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// Protector uses Gatekeeper to verify the LSKF
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byte[] gkPwdToken = passwordTokenToGkInput(pwdToken);
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byte[] gkPassword = stretchedLskfToGkPassword(stretchedLskf);
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GateKeeperResponse response;
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try {
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response = gatekeeper.verifyChallenge(fakeUid(userId), 0L,
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pwd.passwordHandle, gkPwdToken);
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pwd.passwordHandle, gkPassword);
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} catch (RemoteException e) {
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Slog.e(TAG, "gatekeeper verify failed", e);
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result.gkResponse = VerifyCredentialResponse.ERROR;
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@@ -1072,7 +1073,7 @@ public class SyntheticPasswordManager {
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GateKeeperResponse reenrollResponse;
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try {
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reenrollResponse = gatekeeper.enroll(fakeUid(userId),
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pwd.passwordHandle, gkPwdToken, gkPwdToken);
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pwd.passwordHandle, gkPassword, gkPassword);
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} catch (RemoteException e) {
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Slog.w(TAG, "Fail to invoke gatekeeper.enroll", e);
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reenrollResponse = GateKeeperResponse.ERROR;
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@@ -1098,7 +1099,7 @@ public class SyntheticPasswordManager {
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return result;
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}
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sid = sidFromPasswordHandle(pwd.passwordHandle);
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protectorSecret = transformUnderSecdiscardable(pwdToken,
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protectorSecret = transformUnderSecdiscardable(stretchedLskf,
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loadSecdiscardable(protectorId, userId));
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}
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// Supplied credential passes first stage weaver/gatekeeper check so it should be correct.
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@@ -1468,18 +1469,20 @@ public class SyntheticPasswordManager {
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return String.format("%s%x", PROTECTOR_KEY_ALIAS_PREFIX, protectorId);
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}
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private byte[] computePasswordToken(LockscreenCredential credential, PasswordData data) {
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private byte[] stretchLskf(LockscreenCredential credential, PasswordData data) {
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final byte[] password = credential.isNone() ? DEFAULT_PASSWORD : credential.getCredential();
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return scrypt(password, data.salt, 1 << data.scryptLogN, 1 << data.scryptLogR,
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1 << data.scryptLogP, PASSWORD_TOKEN_LENGTH);
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1 << data.scryptLogP, STRETCHED_LSKF_LENGTH);
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}
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private byte[] passwordTokenToGkInput(byte[] token) {
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return SyntheticPasswordCrypto.personalizedHash(PERSONALIZATION_USER_GK_AUTH, token);
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private byte[] stretchedLskfToGkPassword(byte[] stretchedLskf) {
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return SyntheticPasswordCrypto.personalizedHash(PERSONALIZATION_USER_GK_AUTH,
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stretchedLskf);
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}
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private byte[] passwordTokenToWeaverKey(byte[] token) {
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byte[] key = SyntheticPasswordCrypto.personalizedHash(PERSONALIZATION_WEAVER_KEY, token);
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private byte[] stretchedLskfToWeaverKey(byte[] stretchedLskf) {
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byte[] key = SyntheticPasswordCrypto.personalizedHash(PERSONALIZATION_WEAVER_KEY,
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stretchedLskf);
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if (key.length < mWeaverConfig.keySize) {
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throw new IllegalArgumentException("weaver key length too small");
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}
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