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͋Μ͍͟Ώ͖ (@yanzm)
&ODSZQUFE4IBSFE1SFGFSFODFT͕
EFQSFDBUFEʹͳͬͪΌͬͨʂ
Ͳ͏͠Α͏ʂ
1
2025.9.12
DroidKaigi 2025
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:VLJ"O[BJ
w "OESPJE&OHJOFFS
w (PPHMF%FWFMPQFS&YQFSUGPS"OESPJE
w 9 UXJUUFS
!ZBO[N
w CMPHZBO[NCMPHTQPUDPN
w גࣜձࣾϑΟΧදऔక
w ࡳຈɾؔ౦ڌੜ׆
2
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"HFOEB
w +FUQBDL4FDVSJUZ
w ͳͥඇਪ EFQSFDBUFE
ʹͳͬͨͷ͔
w Ҡߦઌͷબࢶ
w ϚΠάϨʔγϣϯ
w க໋తΫϥογϡͷରԠ
3
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+FUQBDL4FDVSJUZ
4
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+FUQBDL4FDVSJUZ +FU4FD
w "OESPJE9ϥΠϒϥϦ܈ͷҰͭ
w BOESPJEYTFDVSJUZάϧʔϓ
w TFDVSJUZDSZQUPEFQSFDBUFE
w TFDVSJUZBQQBVUIFOUJDBUPS
w TFDVSJUZBQQBVUIFOUJDBUPSUFTUJOH
w TFDVSJUZJEFOUJUZDSFEFOUJBM
5
https://developer.android.com/jetpack/androidx/releases/security
https://developer.android.com/privacy-and-security/cryptography#security-crypto-jetpack-deprecated
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TFDVSJUZDSZQUP
w (PPHMF*0Ͱൃද
w TUBCMF݄
w ηΩϡϦςΟͷϕετϓϥΫςΟεΛ؆ૉԽ͢ΔͨΊʹઃܭ͞ΕͨϥΠϒϥϦ
w +$"ͷΑ͏ͳϨϕϧ"1*ඇৗʹڧྗ͕ͩෳࡶͰޡ༻͍͢͠
w ઐՈʹΑͬͯݕূ͞Εͨ҆શͳσϑΥϧτઃఆΛఏڙ
w NJO4EL7FSTJPOʢ"OESPJE.BSTINBMMPXʣ
w ,FZ(FO1BSBNFUFS4QFDΛར༻͢ΔͨΊ
6
https://android-developers.googleblog.com/2019/05/whats-new-with-android-jetpack.html
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ओཁͳػೳ
w &ODSZQUFE4IBSFE1SFGFSFODFT
w &ODSZQUFE'JMF
7
https://developer.android.com/reference/kotlin/androidx/security/crypto/package-summary
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&ODSZQUFE4IBSFE1SFGFSFODFT
w 4IBSFE1SFGFSFODFTΠϯλʔϑΣʔεΛ࣮͠ɺΩʔͱͷ྆ํΛࣗಈతʹ
҉߸Խ͢ΔΫϥε
8
val masterKey = MasterKey.Builder(context)
.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
.build()
val pref: SharedPreferences = EncryptedSharedPreferences.create(
context,
"secret_shared_prefs",
masterKey,
EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)
pref.edit { … }
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&ODSZQUFE'JMF
w ϑΝΠϧͷಡΈॻ͖Λ҉߸Խ͢ΔϢʔςΟϦςΟ
9
val masterKey = MasterKey.Builder(context)
.setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
.build()
val encryptedFile = EncryptedFile.Builder(
context,
File(context.filesDir, "secret_data"),
masterKey,
EncryptedFile.FileEncryptionScheme.AES256_GCM_HKDF_4KB
).build()
val encryptedOutputStream = encryptedFile.openFileOutput()
val encryptedInputStream = encryptedFile.openFileInput()
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෦ͷґଘؔ
w TFDVSJUZDSZQUPˠ5JOLˠ"OESPJE,FZTUPSFˠ0&.
fi
SNXBSF
IBSEXBSF
w 5JOL(PPHMFͷϚϧνϓϥοτϑΥʔϜରԠͷΦʔϓϯιʔε҉߸ԽϥΠ
ϒϥϦ
w IUUQTHJUIVCDPNUJOLDSZQUPUJOLKBWB
10
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෦ߏߏγεςϜ
w ϚελʔΩʔ"OESPJE,FZTUPSFʹੜɾอ͞ΕɺΞϓϦͷϓϩηε
ۭؒʹܾͯ͠࿐ग़͠ͳ͍ڧྗͳ伴
w Ωʔηοτ࣮ࡍͷσʔλΛ҉߸Խ͢ΔͨΊͷαϒΩʔͷू߹ମ
11
ϚελʔΩʔ
Android Keystore
҉߸Խ
σʔλ
SharedPreferences ͷ XML
Ωʔηοτ
҉߸Խ
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&ODSZQUFE4IBSFE1SFGFSFODFTͷ҉߸ԽεΩʔϜ
w ͷ҉߸Խ
w ඇܾఆతͳ"&4@($.Λ༻
w ಉ͡ฏจΛෳճ҉߸Խͯ͠ɺຖճҟͳΔ҉߸จ͕ੜ͞ΕΔ
w Ωʔͷ҉߸Խ
w ܾఆతͳ"&4@4*7Λ༻
w ಉ͡Ωʔৗʹಉ͡҉߸จʹม͞ΕΔ
12
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&ODSZQUFE4IBSFE1SFGFSFODFTͷத
13
12a90104ce…
AYMKS+BZSF6B6Mmxan…
1288015e…
12a90104ce…
AYMKS+C1JGpFULdDV…
1288015e…
ಉ͡ฏจΛ҉߸Խͯ͠
ҟͳΔ҉߸จʹͳΔ
ৗʹಉ͡҉߸จʹͳΔ
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ͳͥඇਪ EFQSFDBUFE
ʹ
ͳͬͨͷ͔
14
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ୈҰͷཁҼɿ҆ఆੑͷةػʢٕज़తཧ༝ʣ
w ಛఆͷ0&.σόΠεͰൃੜͨ͠ɺճ෮ෆೳͳக໋తΫϥογϡ
w ىಈ࣌ʹൃੜ͢Δ͜ͱ͕ଟ͘Ϣʔβʔ͕ΞϓϦΛશ͘༻Ͱ͖ͳ͘ͳΔ
w "OESPJEΤίγεςϜͷʮஅยԽʯ
15
https://issuetracker.google.com/issues/176215143
https://issuetracker.google.com/issues/370009394
https://issuetracker.google.com/issues/367562662
https://issuetracker.google.com/issues/147480931
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ୈೋͷཁҼɿࢥతసʢηΩϡϦςΟ্ͷཧ༝ʣ
w ʮͦͷσʔλɺຊʹσόΠε্ʹอଘ͢Δඞཁ͕͋Δͷ͔ʁʯ
w ࠷҆શͳσʔλɺͦͦอଘ͠ͳ͍σʔλ
w 04ϨϕϧͷϑΝΠϧϕʔε҉߸Խ αϯυϘοΫεϞσϧʹΑΔอޢ
w 04ͷอޢΛ৴ͯ͡ɺ༨ܭͳ҉߸Խ͠ͳ͍
w 04ͷอޢΛ͑Δ҉߸Խ͕ຊʹඞཁͳ΄Ͳػີੑ͕ߴ͍σʔλ
w ։ൃऀநԽʹཔΔͷͰͳ͘ɺͦͷϓϩηεΛશʹཧղ͠ɺ੍ޚ͢
ΔΛෛ͏͖
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Ҡߦઌͷબࢶ
17
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&ODSZQUFE4IBSFE1SFGFSFODFTͷҠߦઌ
w TFDVSJUZDSZQUPΛ͍ଓ͚Δ
w 5JOLʢ෦Ͱ"OESPJE,FZTUPSF༻ʣ 4IBSFE1SFGFSFODFT
w 5JOLʢ෦Ͱ"OESPJE,FZTUPSF༻ʣ %BUB4UPSF
w "OESPJE,FZTUPSF $JQIFS 4IBSFE1SFGFSFODFT
w "OESPJE,FZTUPSF $JQIFS %BUB4UPSF
18
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"OESPJE,FZTUPSF $JQIFS
19
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"OESPJE,FZTUPSF
w ҉߸伴Λίϯςφʹ֨ೲ͠ɺσόΠε͔Βͷநग़Λࠔʹ͢Δ͜ͱΛతͱ
ͨ͠γεςϜϨϕϧͷαʔϏε
w 伴ϚςϦΞϧͷඇΤΫεϙʔτੑ
w ϋʔυΣΞϨϕϧͷอޢ
w 5&& 5SVTUFE&YFDVUJPO&OWJSPONFOU
04ຊମ͔Βִ͞Εͨɺϓϩ
ηοαͷ҆શͳ࣮ߦڥ
w 4USPOH#PYઐ༻ͷλϯύʔੑΛ࣋ͭϋʔυΣΞνοϓ
20
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伴ͷΞΫηε੍ޚ
w Ϣʔβʔೝূͷཁٻ
w 伴ͷ༻લʹࢦೝূإೝূͳͲͷੜମೝূΛϢʔβʔʹཁٻ
w ༗ޮظؒͷઃఆ
w 伴͕༗ޮͳظؒʢ։࢝࣌ͱऴྃ࣌ʣΛࢦఆ
w ҉߸Խύϥϝʔλͷ੍ݶ
w ಛఆͷΞϧΰϦζϜɺϒϩοΫϞʔυɺύσΟϯάํࣜͰͷΈ伴ͷ༻ΛڐՄ
w ʜ
21
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+BWB$SZQUPHSBQIZ"SDIJUFDUVSF +$"
w +$"ͷΫϥεੜ࣌ʹϓϩόΠμͱͯ͠l"OESPJE,FZ4UPSFzΛࢦఆ͢Δ
22
val keyStore = KeyStore.getInstance("AndroidKeyStore")
val keyPairGenerator = KeyPairGenerator.getInstance(
KeyProperties.KEY_ALGORITHM_EC,
"AndroidKeyStore"
)
val keyGenerator = KeyGenerator.getInstance(
KeyProperties.KEY_ALGORITHM_AES,
"AndroidKeyStore"
)
https://developer.android.com/privacy-and-security/keystore#UsingAndroidKeyStore
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4FDSFU,FZͷੜ
23
private const val ANDROID_KEY_STORE_PROVIDER = "AndroidKeyStore"
private const val KEY_STORE_ALIAS = "my_data_key_store_alias"
private fun getOrCreateSecretKey(): SecretKey {
val keyStore = KeyStore.getInstance(ANDROID_KEY_STORE_PROVIDER).apply {
load(null)
}
if (keyStore.containsAlias(KEY_STORE_ALIAS)) {
val entry = keyStore.getEntry(KEY_STORE_ALIAS, null)
return (entry as KeyStore.SecretKeyEntry).secretKey
}
// 伴Λੜ
…
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4FDSFU,FZͷੜ
24
https://developer.android.com/privacy-and-security/cryptography#choose-algorithm
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private const val ANDROID_KEY_STORE_PROVIDER = "AndroidKeyStore"
private const val KEY_STORE_ALIAS = "my_data_key_store_alias"
private fun getOrCreateSecretKey(): SecretKey {
…
// 伴Λੜ
val params = KeyGenParameterSpec.Builder(
KEY_STORE_ALIAS,
KeyProperties.PURPOSE_ENCRYPT or KeyProperties.PURPOSE_DECRYPT
)
.setBlockModes(KeyProperties.BLOCK_MODE_GCM)
.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
.setKeySize(256)
.build()
val keyGenerator = KeyGenerator.getInstance(
KeyProperties.KEY_ALGORITHM_AES, ANDROID_KEY_STORE_PROVIDER
)
keyGenerator.init(params)
return keyGenerator.generateKey()
}
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"&4($./P1BEEJOH
w "&"%ʢ"VUIFOUJDBUFE&ODSZQUJPOXJUI"TTPDJBUFE%BUBʣ҉߸
w σʔλͷػີੑʢ҉߸Խʣ͚ͩͰͳ͘ɺσʔλͷશੑͱೝূੑʢվ͟ΜΛ
ݕ͢Δೝূλάʣಉ࣌ʹఏڙ
w ॳظԽϕΫτϧʢ*7*OJUJBMJ[BUJPO7FDUPSʣ
26
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ॳظԽϕΫτϧʢ*7*OJUJBMJ[BUJPO7FDUPSʣ
w ಉ͡伴Ͱಉ͡σʔλΛ҉߸Խͯ͠ɺຖճҟͳΔ҉߸จ͕Ͱ͖ΔΑ͏ʹ͢Δ
ͨΊͷɺϥϯμϜͳσʔλ
w "&4($.Ͱಉ͡伴ʹରͯ͠*7Λ͍ճ͢ͷઈରʹμϝ
27
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*7ͷཧํ๏
҉߸Խૢ࡞ͷͨͼʹɺ҉߸తʹ҆શͳ৽͍͠ϥϯμϜ*7Λੜʢ/*45ʹ
ΑΔ($.Ͱͷ*7ͷਪόΠτʣ
w $JQIFSͰߦͬͯ͘ΕΔ
*7Λ҉߸จͱҰॹʹอଘʢҰൠతʹ*7Λ҉߸จͷઌ಄ʹ݁߹ʣ
෮߸࣌ʹɺอଘ͓͍ͯͨ͠*7Λͬͯ$JQIFSΛॳظԽ
28
http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
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private const val TRANSFORMATION = "AES/GCM/NoPadding"
private const val IV_SIZE_BYTES = 12
private const val TAG_SIZE_BITS = 128
fun encrypt(plaintext: String): String {
val cipher = Cipher.getInstance(TRANSFORMATION)
cipher.init(Cipher.ENCRYPT_MODE, getOrCreateSecretKey())
val ciphertext = cipher.doFinal(plaintext.toByteArray(Charsets.UTF_8))
val ivAndCiphertext = cipher.iv + ciphertext // IV ͱ҉߸จΛ݁߹
return Base64.getEncoder().encodeToString(ivAndCiphertext)
}
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private const val TRANSFORMATION = "AES/GCM/NoPadding"
private const val IV_SIZE_BYTES = 12
private const val TAG_SIZE_BITS = 128
fun decrypt(encryptedString: String): String {
val cipher = Cipher.getInstance(TRANSFORMATION)
val ivAndCiphertext = Base64.getDecoder().decode(encryptedString)
// อଘ͓͍ͯͨ͠ IV Λ༻
val spec =
GCMParameterSpec(TAG_SIZE_BITS, ivAndCiphertext, 0, IV_SIZE_BYTES)
cipher.init(Cipher.DECRYPT_MODE, getOrCreateSecretKey(), spec)
val plaintextBytes = cipher.doFinal(
/* input = */ ivAndCiphertext, /* inputOffset = */ IV_SIZE_BYTES,
/* inputLen = */ ivAndCiphertext.size - IV_SIZE_BYTES
)
return String(plaintextBytes, Charsets.UTF_8)
}
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5JOL
31
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5JOL
w IUUQTHJUIVCDPNUJOLDSZQUPUJOLKBWB
w TFDVSJUZDSZQUPˠ5JOL+BWB
w MBUFTU5JOL+BWB
32
implementation("com.google.crypto.tink:tink-android:1.18.0")
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&ODSZQUFE4IBSFE1SFGFSFODFTͰͷ5JOL༻
33
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&ODSZQUFE4IBSFE1SFGFSFODFTͰͷ5JOL༻
34
1.16.0 ͰՃ
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35
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ΩʔηοτػೳΛΘͳ͍߹
36
class TinkHelper {
private val aead: Aead
init {
AeadConfig.register()
if(!AndroidKeystore.hasKey(KEY_STORE_ALIAS)) {
AndroidKeystore.generateNewAes256GcmKey(KEY_STORE_ALIAS)
}
aead = AndroidKeystore.getAead(KEY_STORE_ALIAS)
}
…
}
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37
class TinkHelper {
private val aead: Aead
…
fun encrypt(plaintext: String): String {
val plaintextBytes = plaintext.toByteArray(Charsets.UTF_8)
val encrypted = aead.encrypt(plaintextBytes, ByteArray(0))
return Base64.getEncoder().encodeToString(encrypted)
}
fun decrypt(encryptedString: String): String {
val encrypted = Base64.getDecoder().decode(encryptedString)
val plaintextBytes = aead.decrypt(encrypted, ByteArray(0))
return String(plaintextBytes, Charsets.UTF_8)
}
}
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ΩʔηοτػೳΛ͍͍ͨ߹
38
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ΩʔηοτػೳΛ͍͍ͨ߹
w Ωʔηοτػೳ͕ຊʹඞཁ͔ߟ͑Δ
w ͕͞ඞཁʁʢ"OESPJE,FZTUPSFΛͬͨ߹ΑΓ͍ʣ
w ߏͷηΩϡϦςΟ͕ඞཁʁ
w 伴Λϩʔςʔγϣϯ͍ͨ͠ʁ
w ΩʔόϦϡʔͷΩʔ໊҉߸Խ͢Δඞཁ͋Δʁ
39
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ΩʔηοτػೳΛ͍͍ͨ߹
w Ωʔηοτػೳ͕ຊʹඞཁ͔ߟ͑Δ
w ͕͞ඞཁʁʢ"OESPJE,FZTUPSFΛͬͨ߹ΑΓ͍ʣ
w ߏͷηΩϡϦςΟ͕ඞཁʁ
w 伴Λϩʔςʔγϣϯ͍ͨ͠ʁ
w ΩʔόϦϡʔͷΩʔ໊҉߸Խ͢Δඞཁ͋Δʁ
w 5JOLͷΩʔηοτػೳΛΑ͘ཧղ͔ͯ͠Β͏
40
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41
class TinkHelperWithKeyset(context: Context) {
private val aead: Aead
private val keysetPref: SharedPreferences by lazy { … }
init {
…
val masterKeyAead = AndroidKeystore.getAead(KEY_STORE_MASTER_KEY_ALIAS)
val keysetHex = keysetPref.getString("keyset_name", null)
val handle = if (keysetHex == null) {
KeysetHandle.generateNew(KeyTemplates.get("AES256_GCM").toParameters()).also {
val encryptedKeyset =
TinkProtoKeysetFormat.serializeEncryptedKeyset(it, masterKeyAead, ByteArray(0))
keysetPref.edit { putString("keyset_name", Hex.encode(encryptedKeyset)) }
}
} else {
LegacyKeysetSerialization.parseEncryptedKeyset(
BinaryKeysetReader.withBytes(Hex.decode(keysetHex)),
masterKeyAead,
ByteArray(0)
)
}
aead = handle.getPrimitive(RegistryConfiguration.get(), Aead::class.java)
}
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ϚΠάϨʔγϣϯ
42
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ϚΠάϨʔγϣϯͷεςοϓ
ϚΠάϨʔγϣϯࡁΈ͔Ͳ͏͔νΣοΫ͢Δ
w ྫʣϚΠάϨʔγϣϯࡁΈ͔Ͳ͏͔ͷϑϥάΛӬଓԽ͢Δ
w ྫʣTFDVSJUZDSZQUPͷϚελʔΩʔ͕ଘࡏ͍ͯ͠Δ͔Ͳ͏͔Ͱஅ
43
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ϚΠάϨʔγϣϯͷεςοϓ
ϚΠάϨʔγϣϯࡁΈ͔Ͳ͏͔νΣοΫ͢Δ
&ODSZQUFE4IBSFE1SFGFSFODFʹอଘ͍ͯ͠ΔσʔλΛϝϞϦ্ʹऔΓग़͢
৽͘͠࡞ͨ͠"OESPJE,FZTUPSF $JQIFS ͘͠5JOL
Ͱ҉߸Խ͢Δ
৽͘͠࡞ͨ͠%BUB4UPSF4IBSFE1SFGFSFODFTʹอଘ͢Δ
TFDVSJUZDSZQUPͷΩʔηοτ͕อଘ͞Ε͍ͯͨ4IBSFE1SFGFSFODFTϑΝ
ΠϧΛআ͢Δ
"OESPJE,FZTUPSFͷTFDVSJUZDSZQUPͷϚελʔΩʔΛআ͢Δ
44
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ϚελʔΩʔͱΩʔηοτͷআ
45
// delete SharedPreferences files
deleteSharedPreferences("secret_shared_prefs")
// delete MasterKey
val keyStore = KeyStore.getInstance("AndroidKeyStore").apply {
load(null)
}
if (keyStore.containsAlias(MasterKey.DEFAULT_MASTER_KEY_ALIAS)) {
keyStore.deleteEntry(MasterKey.DEFAULT_MASTER_KEY_ALIAS)
}
EncryptedSharedPreferences.create(
applicationContext,
"secret_shared_prefs",
…
)
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க໋తΫϥογϡͷରԠ
46
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ใࠂ͞Ε͍ͯΔΫϥογϡͷཁҼ
w όοΫΞοϓઃఆͷෆ
w 0&.σόΠεͷ"OESPJE,FZTUPSFͷόά
47
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όοΫΞοϓઃఆͷෆ
48
όοΫΞοϓ
Android Keystore
SharedPreferences
ͷ XML
σόΠε A σόΠε B
Android Keystore
❌
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όοΫΞοϓઃఆͷෆ
49
όοΫΞοϓ
Android Keystore
SharedPreferences
ͷ XML
σόΠε A σόΠε B
Android Keystore
❌
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όοΫΞοϓઃఆͷෆ
50
όοΫΞοϓ
Android Keystore
SharedPreferences
ͷ XML
σόΠε A σόΠε B
Android Keystore
❌
SharedPreferences
ͷ XML
ෳ߹ԽͰ͖ͳ͍
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όοΫΞοϓઃఆͷෆ
51
όοΫΞοϓ
Android Keystore
SharedPreferences
ͷ XML
σόΠε A σόΠε B
Android Keystore
❌
SharedPreferences
ͷ XML
ෳ߹ԽͰ͖ͳ͍
❌
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όοΫΞοϓઃఆ
52
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53
…
ͱಉ͡
…
https://developer.android.com/identity/data/autobackup?utm_source=chatgpt.com#IncludingFiles
data_extraction_rules.xml
EncryptedSharedPreferences.create() Ͱࢦఆ໊ͨ͠લ
EncryptedFile.Builder ͰΘΕ͍ͯΔσϑΥϧτ໊
withSharedPref()Ͱࢦఆͨ͠
໊લʢΩʔηοτͷอଘઌʣ
҉߸Խͨ͠σʔλͷอଘઌ
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0&.σόΠεͷ"OESPJE,FZTUPSFͷόά
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https://github.com/tink-crypto/tink/issues/535#issuecomment-912170221
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"OESPJE,FZTUPSFͷόάʹରॲ͢Δ
ྫ֎ΛัଊͰ͖ΔΑ͏ʹ͢Δ
"OESPJE,FZTUPSFͷ伴ɺ҉߸Խͨ͠σʔλ͕อଘ͞Ε͍ͯΔϑΝΠϧɺ
ʢ5JOLΛ͍ͬͯΔ߹ΩʔηοτʣΛআ͢Δ
σʔλΛ࠶औಘ͢ΔʢྫϢʔβʔʹϩάΠϯͯ͠͠Β͏ʣ
伴Λ࡞Γ͢
৽͍͠伴Ͱ࠶औಘͨ͠σʔλΛ҉߸Խͯ͠อଘ͢Δ
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ӬٱʹࣦΘΕͯࠔΔͷอଘ͠ͳ͍ʢ࠶औಘͰ͖ΔͷͷΈʹ͢Δʣ
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·ͱΊ
w ຊʹ҉߸Խ͢Δඞཁ͕͋Δͷ͔Α͘ߟ͑Δ
w ӬٱʹࣦΘΕͯࠔΔͷอଘ͠ͳ͍
w "OESPJE,FZTUPSF $JQIFS͘͠5JOLͰͷ҉߸ԽʹҠߦ͢Δ
w ҉߸Խ͞Εͨσʔλ͕อଘ͞Ε͍ͯΔϑΝΠϧΛόοΫΞοϓର͔Βআ͘
w "OESPJE,FZTUPSFͷόάʹૺ۰͢ΔલఏͰରԠࡦΛ࣮͓ͯ͘͠
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