refactor: un-flatten module structure

10 files changed, 902 insertions, 0 deletions

diff --git a/format/common/src/main/kotlin/app/passwordstore/data/passfile/PasswordEntry.kt b/format/common/src/main/kotlin/app/passwordstore/data/passfile/PasswordEntry.kt
new file mode 100644
index 00000000..1618374f
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/data/passfile/PasswordEntry.kt
@@ -0,0 +1,231 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.data.passfile
+
+import androidx.annotation.VisibleForTesting
+import app.passwordstore.util.time.UserClock
+import app.passwordstore.util.totp.Otp
+import app.passwordstore.util.totp.TotpFinder
+import com.github.michaelbull.result.mapBoth
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
+import kotlin.collections.set
+import kotlin.coroutines.coroutineContext
+import kotlin.time.Duration.Companion.milliseconds
+import kotlin.time.Duration.Companion.seconds
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.isActive
+
+/** Represents a single entry in the password store. */
+public class PasswordEntry
+@AssistedInject
+constructor(
+  /** A time source used to calculate the TOTP */
+  private val clock: UserClock,
+  /** [TotpFinder] implementation to extract data from a TOTP URI */
+  private val totpFinder: TotpFinder,
+  /** The content of this entry, as an array of bytes. */
+  @Assisted bytes: ByteArray,
+) {
+
+  private val content = bytes.decodeToString()
+
+  /** The password text for this entry. Can be null. */
+  public val password: String?
+
+  /** The username for this entry. Can be null. */
+  public val username: String?
+
+  /** A [String] to [String] [Map] of the extra content of this entry, in a key:value fashion. */
+  public val extraContent: Map<String, String>
+
+  /**
+   * Direct [String] representation of the extra content of this entry, before any transforms are
+   * applied. Only use this when the extra content is required in a formatting-preserving manner.
+   */
+  public val extraContentString: String
+
+  /**
+   * A [Flow] providing the current TOTP. It will start emitting only when collected. If this entry
+   * does not have a TOTP secret, the flow will never emit. Users should call [hasTotp] before
+   * collection to check if it is valid to collect this [Flow].
+   */
+  public val totp: Flow<Totp> = flow {
+    require(totpSecret != null) { "Cannot collect this flow without a TOTP secret" }
+    do {
+      val otp = calculateTotp()
+      emit(otp)
+      delay(THOUSAND_MILLIS.milliseconds)
+    } while (coroutineContext.isActive)
+  }
+
+  /** Obtain the [Totp.value] for this [PasswordEntry] at the current time. */
+  public val currentOtp: String
+    get() = calculateTotp().value
+
+  /**
+   * String representation of [extraContent] but with authentication related data such as TOTP URIs
+   * and usernames stripped.
+   */
+  public val extraContentWithoutAuthData: String
+  private val totpSecret: String?
+
+  init {
+    val (foundPassword, passContent) = findAndStripPassword(content.split("\n".toRegex()))
+    password = foundPassword
+    extraContentString = passContent.joinToString("\n")
+    extraContentWithoutAuthData = generateExtraContentWithoutAuthData()
+    extraContent = generateExtraContentPairs()
+    username = findUsername()
+    totpSecret = totpFinder.findSecret(content)
+  }
+
+  public fun hasTotp(): Boolean {
+    return totpSecret != null
+  }
+
+  @Suppress("ReturnCount")
+  private fun findAndStripPassword(passContent: List<String>): Pair<String?, List<String>> {
+    if (TotpFinder.TOTP_FIELDS.any { passContent[0].startsWith(it) }) return Pair(null, passContent)
+    for (line in passContent) {
+      for (prefix in PASSWORD_FIELDS) {
+        if (line.startsWith(prefix, ignoreCase = true)) {
+          return Pair(line.substring(prefix.length).trimStart(), passContent.minus(line))
+        }
+      }
+    }
+    return Pair(passContent[0], passContent.minus(passContent[0]))
+  }
+
+  private fun generateExtraContentWithoutAuthData(): String {
+    var foundUsername = false
+    return extraContentString
+      .lineSequence()
+      .filter { line ->
+        return@filter when {
+          USERNAME_FIELDS.any { prefix -> line.startsWith(prefix, ignoreCase = true) } &&
+            !foundUsername -> {
+            foundUsername = true
+            false
+          }
+          TotpFinder.TOTP_FIELDS.any { prefix -> line.startsWith(prefix, ignoreCase = true) } -> {
+            false
+          }
+          else -> {
+            true
+          }
+        }
+      }
+      .joinToString(separator = "\n")
+  }
+
+  private fun generateExtraContentPairs(): Map<String, String> {
+    fun MutableMap<String, String>.putOrAppend(key: String, value: String) {
+      if (value.isEmpty()) return
+      val existing = this[key]
+      this[key] =
+        if (existing == null) {
+          value
+        } else {
+          "$existing\n$value"
+        }
+    }
+
+    val items = mutableMapOf<String, String>()
+    extraContentWithoutAuthData.lines().forEach { line ->
+      // Split the line on ':' and save all the parts into an array
+      // "ABC : DEF:GHI" --> ["ABC", "DEF", "GHI"]
+      val splitArray = line.split(":")
+      // Take the first element of the array. This will be the key for the key-value pair.
+      // ["ABC ", " DEF", "GHI"] -> key = "ABC"
+      val key = splitArray.first().trimEnd()
+      // Remove the first element from the array and join the rest of the string again with
+      // ':' as separator.
+      // ["ABC ", " DEF", "GHI"] -> value = "DEF:GHI"
+      val value = splitArray.drop(1).joinToString(":").trimStart()
+
+      if (key.isNotEmpty() && value.isNotEmpty()) {
+        // If both key and value are not empty, we can form a pair with this so add it to
+        // the map.
+        // key = "ABC", value = "DEF:GHI"
+        items[key] = value
+      } else {
+        // If either key or value is empty, we were not able to form proper key-value pair.
+        // So append the original line into an "EXTRA CONTENT" map entry
+        items.putOrAppend(EXTRA_CONTENT, line)
+      }
+    }
+
+    return items
+  }
+
+  private fun findUsername(): String? {
+    extraContentString.splitToSequence("\n").forEach { line ->
+      for (prefix in USERNAME_FIELDS) {
+        if (line.startsWith(prefix, ignoreCase = true))
+          return line.substring(prefix.length).trimStart()
+      }
+    }
+    return null
+  }
+
+  private fun calculateTotp(): Totp {
+    val digits = totpFinder.findDigits(content)
+    val totpPeriod = totpFinder.findPeriod(content)
+    val totpAlgorithm = totpFinder.findAlgorithm(content)
+    val issuer = totpFinder.findIssuer(content)
+    val millis = clock.millis()
+    val remainingTime = (totpPeriod - ((millis / THOUSAND_MILLIS) % totpPeriod)).seconds
+    Otp.calculateCode(
+        totpSecret!!,
+        millis / (THOUSAND_MILLIS * totpPeriod),
+        totpAlgorithm,
+        digits,
+        issuer
+      )
+      .mapBoth(
+        { code ->
+          return Totp(code, remainingTime)
+        },
+        { throwable -> throw throwable }
+      )
+  }
+
+  @AssistedFactory
+  public interface Factory {
+    public fun create(bytes: ByteArray): PasswordEntry
+  }
+
+  public companion object {
+
+    private const val EXTRA_CONTENT = "Extra Content"
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    public val USERNAME_FIELDS: Array<String> =
+      arrayOf(
+        "login:",
+        "username:",
+        "user:",
+        "account:",
+        "email:",
+        "mail:",
+        "name:",
+        "handle:",
+        "id:",
+        "identity:",
+      )
+    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
+    public val PASSWORD_FIELDS: Array<String> =
+      arrayOf(
+        "password:",
+        "secret:",
+        "pass:",
+      )
+    private const val THOUSAND_MILLIS = 1000L
+  }
+}
diff --git a/format/common/src/main/kotlin/app/passwordstore/data/passfile/Totp.kt b/format/common/src/main/kotlin/app/passwordstore/data/passfile/Totp.kt
new file mode 100644
index 00000000..c279360f
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/data/passfile/Totp.kt
@@ -0,0 +1,6 @@
+package app.passwordstore.data.passfile
+
+import kotlin.time.Duration
+
+/** Holder for a TOTP secret and the duration for which it is valid. */
+public data class Totp(public val value: String, public val remainingTime: Duration)
diff --git a/format/common/src/main/kotlin/app/passwordstore/util/time/UserClock.kt b/format/common/src/main/kotlin/app/passwordstore/util/time/UserClock.kt
new file mode 100644
index 00000000..4ffeb6a6
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/util/time/UserClock.kt
@@ -0,0 +1,26 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.time
+
+import java.time.Clock
+import java.time.Instant
+import java.time.ZoneId
+import javax.inject.Inject
+
+/**
+ * A subclass of [Clock] that uses [Clock.systemDefaultZone] to get a clock that works for the
+ * user's current time zone.
+ */
+public open class UserClock @Inject constructor() : Clock() {
+
+  private val clock = systemDefaultZone()
+
+  override fun withZone(zone: ZoneId): Clock = clock.withZone(zone)
+
+  override fun getZone(): ZoneId = clock.zone
+
+  override fun instant(): Instant = clock.instant()
+}
diff --git a/format/common/src/main/kotlin/app/passwordstore/util/totp/Otp.kt b/format/common/src/main/kotlin/app/passwordstore/util/totp/Otp.kt
new file mode 100644
index 00000000..10e771fe
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/util/totp/Otp.kt
@@ -0,0 +1,90 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.totp
+
+import com.github.michaelbull.result.Err
+import com.github.michaelbull.result.Result
+import com.github.michaelbull.result.runCatching
+import java.nio.ByteBuffer
+import java.util.Locale
+import javax.crypto.Mac
+import javax.crypto.spec.SecretKeySpec
+import kotlin.experimental.and
+import org.apache.commons.codec.binary.Base32
+
+public object Otp {
+
+  private val BASE_32 = Base32()
+  private val STEAM_ALPHABET = "23456789BCDFGHJKMNPQRTVWXY".toCharArray()
+  private const val BYTE_BUFFER_CAPACITY = 8
+  private const val END_INDEX_OFFSET = 4
+  private const val STEAM_GUARD_DIGITS = 5
+  private const val MINIMUM_DIGITS = 6
+  private const val MAXIMUM_DIGITS = 10
+  private const val ALPHABET_LENGTH = 26
+  private const val MOST_SIGNIFICANT_BYTE = 0x7f
+
+  public fun calculateCode(
+    secret: String,
+    counter: Long,
+    algorithm: String,
+    digits: String,
+    issuer: String?,
+  ): Result<String, Throwable> = runCatching {
+    val algo = "Hmac${algorithm.uppercase(Locale.ROOT)}"
+    val decodedSecret = BASE_32.decode(secret)
+    val secretKey = SecretKeySpec(decodedSecret, algo)
+    val digest =
+      Mac.getInstance(algo).run {
+        init(secretKey)
+        doFinal(ByteBuffer.allocate(BYTE_BUFFER_CAPACITY).putLong(counter).array())
+      }
+    // Least significant 4 bits are used as an offset into the digest.
+    val offset = (digest.last() and 0xf).toInt()
+    // Extract 32 bits at the offset and clear the most significant bit.
+    val code = digest.copyOfRange(offset, offset.plus(END_INDEX_OFFSET))
+    code[0] = (MOST_SIGNIFICANT_BYTE and code[0].toInt()).toByte()
+    val codeInt = ByteBuffer.wrap(code).int
+    check(codeInt > 0)
+    // SteamGuard is a horrible OTP implementation that generates non-standard 5 digit OTPs as
+    // well
+    // as uses a custom character set.
+    if (digits == "s" || issuer == "Steam") {
+      var remainingCodeInt = codeInt
+      buildString {
+        repeat(STEAM_GUARD_DIGITS) {
+          append(STEAM_ALPHABET[remainingCodeInt % STEAM_ALPHABET.size])
+          remainingCodeInt /= ALPHABET_LENGTH
+        }
+      }
+    } else {
+      // Base 10, 6 to 10 digits
+      val numDigits = digits.toIntOrNull()
+      when {
+        numDigits == null -> {
+          return Err(IllegalArgumentException("Digits specifier has to be either 's' or numeric"))
+        }
+        numDigits < MINIMUM_DIGITS -> {
+          return Err(
+            IllegalArgumentException("TOTP codes have to be at least $MINIMUM_DIGITS digits long")
+          )
+        }
+        numDigits > MAXIMUM_DIGITS -> {
+          return Err(
+            IllegalArgumentException("TOTP codes can be at most $MAXIMUM_DIGITS digits long")
+          )
+        }
+        else -> {
+          // 2^31 = 2_147_483_648, so we can extract at most 10 digits with the first one
+          // always being 0, 1, or 2. Pad with leading zeroes.
+          val codeStringBase10 = codeInt.toString(MAXIMUM_DIGITS).padStart(MAXIMUM_DIGITS, '0')
+          check(codeStringBase10.length == MAXIMUM_DIGITS)
+          codeStringBase10.takeLast(numDigits)
+        }
+      }
+    }
+  }
+}
diff --git a/format/common/src/main/kotlin/app/passwordstore/util/totp/TotpFinder.kt b/format/common/src/main/kotlin/app/passwordstore/util/totp/TotpFinder.kt
new file mode 100644
index 00000000..d53d76dc
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/util/totp/TotpFinder.kt
@@ -0,0 +1,29 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.totp
+
+/** Defines a class that can extract relevant parts of a TOTP URL for use by the app. */
+public interface TotpFinder {
+
+  /** Get the TOTP secret from the given extra content. */
+  public fun findSecret(content: String): String?
+
+  /** Get the number of digits required in the final OTP. */
+  public fun findDigits(content: String): String
+
+  /** Get the TOTP timeout period. */
+  public fun findPeriod(content: String): Long
+
+  /** Get the algorithm for the TOTP secret. */
+  public fun findAlgorithm(content: String): String
+
+  /** Get the issuer for the TOTP secret, if any. */
+  public fun findIssuer(content: String): String?
+
+  public companion object {
+    public val TOTP_FIELDS: Array<String> = arrayOf("otpauth://totp", "totp:")
+  }
+}
diff --git a/format/common/src/main/kotlin/app/passwordstore/util/totp/UriTotpFinder.kt b/format/common/src/main/kotlin/app/passwordstore/util/totp/UriTotpFinder.kt
new file mode 100644
index 00000000..bb97c90c
--- /dev/null
+++ b/format/common/src/main/kotlin/app/passwordstore/util/totp/UriTotpFinder.kt
@@ -0,0 +1,52 @@
+package app.passwordstore.util.totp
+
+import com.eygraber.uri.Uri
+import javax.inject.Inject
+
+/** [Uri] backed TOTP URL parser. */
+public class UriTotpFinder @Inject constructor() : TotpFinder {
+
+  private companion object {
+    private const val DEFAULT_TOTP_PERIOD = 30L
+  }
+
+  override fun findSecret(content: String): String? {
+    content.split("\n".toRegex()).forEach { line ->
+      if (line.startsWith(TotpFinder.TOTP_FIELDS[0])) {
+        return Uri.parse(line).getQueryParameter("secret")
+      }
+      if (line.startsWith(TotpFinder.TOTP_FIELDS[1], ignoreCase = true)) {
+        return line.split(": *".toRegex(), 2).toTypedArray()[1]
+      }
+    }
+    return null
+  }
+
+  override fun findDigits(content: String): String {
+    return getQueryParameter(content, "digits") ?: "6"
+  }
+
+  override fun findPeriod(content: String): Long {
+    return getQueryParameter(content, "period")?.toLongOrNull() ?: DEFAULT_TOTP_PERIOD
+  }
+
+  override fun findAlgorithm(content: String): String {
+    return getQueryParameter(content, "algorithm") ?: "sha1"
+  }
+
+  override fun findIssuer(content: String): String? {
+    return getQueryParameter(content, "issuer") ?: Uri.parse(content).authority
+  }
+
+  private fun getQueryParameter(content: String, parameterName: String): String? {
+    content.split("\n".toRegex()).forEach { line ->
+      val uri = Uri.parse(line)
+      if (
+        line.startsWith(TotpFinder.TOTP_FIELDS[0]) && uri.getQueryParameter(parameterName) != null
+      ) {
+        return uri.getQueryParameter(parameterName)
+      }
+    }
+    return null
+  }
+}
diff --git a/format/common/src/test/kotlin/app/passwordstore/data/passfile/PasswordEntryTest.kt b/format/common/src/test/kotlin/app/passwordstore/data/passfile/PasswordEntryTest.kt
new file mode 100644
index 00000000..865a13c1
--- /dev/null
+++ b/format/common/src/test/kotlin/app/passwordstore/data/passfile/PasswordEntryTest.kt
@@ -0,0 +1,212 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.data.passfile
+
+import app.cash.turbine.Event
+import app.cash.turbine.test
+import app.passwordstore.util.time.TestUserClock
+import app.passwordstore.util.time.UserClock
+import app.passwordstore.util.totp.UriTotpFinder
+import java.util.Locale
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+import kotlin.test.assertTrue
+import kotlin.time.Duration.Companion.seconds
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.test.runTest
+
+class PasswordEntryTest {
+
+  private val totpFinder = UriTotpFinder()
+
+  private fun makeEntry(content: String, clock: UserClock = fakeClock) =
+    PasswordEntry(
+      clock,
+      totpFinder,
+      content.encodeToByteArray(),
+    )
+
+  @Test
+  fun getPassword() {
+    assertEquals("fooooo", makeEntry("fooooo\nbla\n").password)
+    assertEquals("fooooo", makeEntry("fooooo\nbla").password)
+    assertEquals("fooooo", makeEntry("fooooo\n").password)
+    assertEquals("fooooo", makeEntry("fooooo").password)
+    assertEquals("", makeEntry("\nblubb\n").password)
+    assertEquals("", makeEntry("\nblubb").password)
+    assertEquals("", makeEntry("\n").password)
+    assertEquals("", makeEntry("").password)
+    for (field in PasswordEntry.PASSWORD_FIELDS) {
+      assertEquals("fooooo", makeEntry("\n$field fooooo").password)
+      assertEquals("fooooo", makeEntry("\n${field.uppercase(Locale.getDefault())} fooooo").password)
+      assertEquals("fooooo", makeEntry("GOPASS-SECRET-1.0\n$field fooooo").password)
+      assertEquals("fooooo", makeEntry("someFirstLine\nUsername: bar\n$field fooooo").password)
+    }
+  }
+
+  @Test
+  fun getExtraContent() {
+    assertEquals("bla\n", makeEntry("fooooo\nbla\n").extraContentString)
+    assertEquals("bla", makeEntry("fooooo\nbla").extraContentString)
+    assertEquals("", makeEntry("fooooo\n").extraContentString)
+    assertEquals("", makeEntry("fooooo").extraContentString)
+    assertEquals("blubb\n", makeEntry("\nblubb\n").extraContentString)
+    assertEquals("blubb", makeEntry("\nblubb").extraContentString)
+    assertEquals("blubb", makeEntry("blubb\npassword: foo").extraContentString)
+    assertEquals("blubb", makeEntry("password: foo\nblubb").extraContentString)
+    assertEquals(
+      "blubb\nusername: bar",
+      makeEntry("blubb\npassword: foo\nusername: bar").extraContentString
+    )
+    assertEquals("", makeEntry("\n").extraContentString)
+    assertEquals("", makeEntry("").extraContentString)
+  }
+
+  @Test
+  fun parseExtraContentWithoutAuth() {
+    var entry = makeEntry("username: abc\npassword: abc\ntest: abcdef")
+    assertEquals(1, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("test"))
+    assertEquals("abcdef", entry.extraContent["test"])
+
+    entry = makeEntry("username: abc\npassword: abc\ntest: :abcdef:")
+    assertEquals(1, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("test"))
+    assertEquals(":abcdef:", entry.extraContent["test"])
+
+    entry = makeEntry("username: abc\npassword: abc\ntest : ::abc:def::")
+    assertEquals(1, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("test"))
+    assertEquals("::abc:def::", entry.extraContent["test"])
+
+    entry = makeEntry("username: abc\npassword: abc\ntest: abcdef\ntest2: ghijkl")
+    assertEquals(2, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("test2"))
+    assertEquals("ghijkl", entry.extraContent["test2"])
+
+    entry = makeEntry("username: abc\npassword: abc\ntest: abcdef\n: ghijkl\n mnopqr:")
+    assertEquals(2, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("Extra Content"))
+    assertEquals(": ghijkl\n mnopqr:", entry.extraContent["Extra Content"])
+
+    entry = makeEntry("username: abc\npassword: abc\n:\n\n")
+    assertEquals(1, entry.extraContent.size)
+    assertTrue(entry.extraContent.containsKey("Extra Content"))
+    assertEquals(":", entry.extraContent["Extra Content"])
+  }
+
+  @Test
+  fun getUsername() {
+    for (field in PasswordEntry.USERNAME_FIELDS) {
+      assertEquals("username", makeEntry("\n$field username").username)
+      assertEquals(
+        "username",
+        makeEntry("\n${field.uppercase(Locale.getDefault())} username").username
+      )
+    }
+    assertEquals("username", makeEntry("secret\nextra\nlogin: username\ncontent\n").username)
+    assertEquals("username", makeEntry("\nextra\nusername: username\ncontent\n").username)
+    assertEquals("username", makeEntry("\nUSERNaMe:  username\ncontent\n").username)
+    assertEquals("username", makeEntry("\nlogin:    username").username)
+    assertEquals("foo@example.com", makeEntry("\nemail: foo@example.com").username)
+    assertEquals("username", makeEntry("\nidentity: username\nlogin: another_username").username)
+    assertEquals("username", makeEntry("\nLOGiN:username").username)
+    assertEquals("foo@example.com", makeEntry("pass\nmail:    foo@example.com").username)
+    assertNull(makeEntry("secret\nextra\ncontent\n").username)
+  }
+
+  @Test
+  fun hasUsername() {
+    assertNotNull(makeEntry("secret\nextra\nlogin: username\ncontent\n").username)
+    assertNull(makeEntry("secret\nextra\ncontent\n").username)
+    assertNull(makeEntry("secret\nlogin failed\n").username)
+    assertNull(makeEntry("\n").username)
+    assertNull(makeEntry("").username)
+  }
+
+  @Test
+  fun generatesOtpFromTotpUri() = runTest {
+    val entry = makeEntry("secret\nextra\n$TOTP_URI")
+    assertTrue(entry.hasTotp())
+    entry.totp.test {
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(30.seconds, otp.remainingTime)
+      cancelAndIgnoreRemainingEvents()
+    }
+  }
+
+  /**
+   * Same as [generatesOtpFromTotpUri], but advances the clock by 5 seconds. This exercises the
+   * [Totp.remainingTime] calculation logic, and acts as a regression test to resolve the bug which
+   * blocked https://github.com/Android-Password-Store/Android-Password-Store/issues/1550.
+   */
+  @Test
+  fun generatedOtpHasCorrectRemainingTime() = runTest {
+    val entry = makeEntry("secret\nextra\n$TOTP_URI", TestUserClock.withAddedSeconds(5))
+    assertTrue(entry.hasTotp())
+    entry.totp.test {
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(25.seconds, otp.remainingTime)
+      cancelAndIgnoreRemainingEvents()
+    }
+  }
+
+  @Test
+  fun generatesOtpWithOnlyUriInFile() = runTest {
+    val entry = makeEntry(TOTP_URI)
+    assertNull(entry.password)
+    entry.totp.test {
+      val otp = expectMostRecentItem()
+      assertEquals("818800", otp.value)
+      assertEquals(30.seconds, otp.remainingTime)
+      cancelAndIgnoreRemainingEvents()
+    }
+  }
+
+  @Test
+  fun emitsTotpEverySecond() = runTest {
+    val entry = makeEntry(TOTP_URI)
+    entry.totp.test {
+      delay(3000L)
+      val events = cancelAndConsumeRemainingEvents()
+      assertEquals(3, events.size)
+      assertTrue { events.all { event -> event is Event.Item<Totp> } }
+    }
+  }
+
+  @Test
+  fun onlyLooksForUriInFirstLine() {
+    val entry = makeEntry("id:\n$TOTP_URI")
+    assertNotNull(entry.password)
+    assertTrue(entry.hasTotp())
+    assertNull(entry.username)
+  }
+
+  // https://github.com/android-password-store/Android-Password-Store/issues/1190
+  @Test
+  fun extraContentWithMultipleUsernameFields() {
+    val entry = makeEntry("pass\nuser: user\nid: id\n$TOTP_URI")
+    assertTrue(entry.extraContent.isNotEmpty())
+    assertTrue(entry.hasTotp())
+    assertNotNull(entry.username)
+    assertEquals("pass", entry.password)
+    assertEquals("user", entry.username)
+    assertEquals(mapOf("id" to "id"), entry.extraContent)
+  }
+
+  companion object {
+
+    @Suppress("MaxLineLength")
+    const val TOTP_URI =
+      "otpauth://totp/ACME%20Co:john@example.com?secret=HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ&issuer=ACME%20Co&algorithm=SHA1&digits=6&period=30"
+
+    val fakeClock = TestUserClock()
+  }
+}
diff --git a/format/common/src/test/kotlin/app/passwordstore/util/time/TestUserClock.kt b/format/common/src/test/kotlin/app/passwordstore/util/time/TestUserClock.kt
new file mode 100644
index 00000000..8a860a39
--- /dev/null
+++ b/format/common/src/test/kotlin/app/passwordstore/util/time/TestUserClock.kt
@@ -0,0 +1,33 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.time
+
+import java.time.Clock
+import java.time.Instant
+import java.time.ZoneId
+import java.time.ZoneOffset.UTC
+
+/**
+ * Implementation of [UserClock] that is fixed to [Instant.EPOCH] for deterministic time-based tests
+ */
+class TestUserClock(instant: Instant) : UserClock() {
+
+  constructor() : this(Instant.EPOCH)
+
+  private var clock = fixed(instant, UTC)
+
+  override fun withZone(zone: ZoneId): Clock = clock.withZone(zone)
+
+  override fun getZone(): ZoneId = UTC
+
+  override fun instant(): Instant = clock.instant()
+
+  companion object {
+    fun withAddedSeconds(secondsToAdd: Long): TestUserClock {
+      return TestUserClock(Instant.EPOCH.plusSeconds(secondsToAdd))
+    }
+  }
+}
diff --git a/format/common/src/test/kotlin/app/passwordstore/util/totp/OtpTest.kt b/format/common/src/test/kotlin/app/passwordstore/util/totp/OtpTest.kt
new file mode 100644
index 00000000..54ac492d
--- /dev/null
+++ b/format/common/src/test/kotlin/app/passwordstore/util/totp/OtpTest.kt
@@ -0,0 +1,168 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.totp
+
+import com.github.michaelbull.result.get
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertNotNull
+import kotlin.test.assertNull
+
+class OtpTest {
+
+  private fun generateOtp(
+    counter: Long,
+    secret: String = "JBSWY3DPEHPK3PXP",
+    algorithm: String = "SHA1",
+    digits: String = "6",
+    issuer: String? = null,
+  ): String? {
+    return Otp.calculateCode(secret, counter, algorithm, digits, issuer).get()
+  }
+
+  @Test
+  fun otpGeneration6Digits() {
+    assertEquals(
+      "953550",
+      generateOtp(
+        counter = 1593333298159 / (1000 * 30),
+      )
+    )
+    assertEquals(
+      "275379",
+      generateOtp(
+        counter = 1593333571918 / (1000 * 30),
+      )
+    )
+    assertEquals(
+      "867507",
+      generateOtp(
+        counter = 1593333600517 / (1000 * 57),
+      )
+    )
+  }
+
+  @Test
+  fun otpGeneration10Digits() {
+    assertEquals(
+      "0740900914",
+      generateOtp(
+        counter = 1593333655044 / (1000 * 30),
+        digits = "10",
+      )
+    )
+    assertEquals(
+      "0070632029",
+      generateOtp(
+        counter = 1593333691405 / (1000 * 30),
+        digits = "10",
+      )
+    )
+    assertEquals(
+      "1017265882",
+      generateOtp(
+        counter = 1593333728893 / (1000 * 83),
+        digits = "10",
+      )
+    )
+  }
+
+  @Test
+  fun otpGenerationIllegalInput() {
+    assertNull(
+      generateOtp(
+        counter = 10000,
+        algorithm = "SHA0",
+        digits = "10",
+      )
+    )
+    assertNull(
+      generateOtp(
+        counter = 10000,
+        digits = "a",
+      )
+    )
+    assertNull(
+      generateOtp(
+        counter = 10000,
+        algorithm = "SHA1",
+        digits = "5",
+      )
+    )
+    assertNull(
+      generateOtp(
+        counter = 10000,
+        digits = "11",
+      )
+    )
+    assertNull(
+      generateOtp(
+        counter = 10000,
+        secret = "JBSWY3DPEHPK3PXPAAAAB",
+        digits = "6",
+      )
+    )
+  }
+
+  @Test
+  fun otpGenerationUnusualSecrets() {
+    assertEquals(
+      "127764",
+      generateOtp(
+        counter = 1593367111963 / (1000 * 30),
+        secret = "JBSWY3DPEHPK3PXPAAAAAAAA",
+      )
+    )
+    assertEquals(
+      "047515",
+      generateOtp(
+        counter = 1593367171420 / (1000 * 30),
+        secret = "JBSWY3DPEHPK3PXPAAAAA",
+      )
+    )
+  }
+
+  @Test
+  fun otpGenerationUnpaddedSecrets() {
+    // Secret was generated with `echo 'string with some padding needed' | base32`
+    // We don't care for the resultant OTP's actual value, we just want both the padded and
+    // unpadded variant to generate the same one.
+    val unpaddedOtp =
+      generateOtp(
+        counter = 1593367171420 / (1000 * 30),
+        secret = "ON2HE2LOM4QHO2LUNAQHG33NMUQHAYLEMRUW4ZZANZSWKZDFMQFA",
+      )
+    val paddedOtp =
+      generateOtp(
+        counter = 1593367171420 / (1000 * 30),
+        secret = "ON2HE2LOM4QHO2LUNAQHG33NMUQHAYLEMRUW4ZZANZSWKZDFMQFA====",
+      )
+
+    assertNotNull(unpaddedOtp)
+    assertNotNull(paddedOtp)
+    assertEquals(unpaddedOtp, paddedOtp)
+  }
+
+  @Test
+  fun generateSteamTotp() {
+    val issuerOtp =
+      generateOtp(
+        counter = 48297900 / (1000 * 30),
+        secret = "STK7746GVMCHMNH5FBIAQXGPV3I7ZHRG",
+        issuer = "Steam",
+      )
+    val digitsOtp =
+      generateOtp(
+        counter = 48297900 / (1000 * 30),
+        secret = "STK7746GVMCHMNH5FBIAQXGPV3I7ZHRG",
+        digits = "s",
+      )
+    assertNotNull(issuerOtp)
+    assertNotNull(digitsOtp)
+    assertEquals("6M3CT", issuerOtp)
+    assertEquals("6M3CT", digitsOtp)
+  }
+}
diff --git a/format/common/src/test/kotlin/app/passwordstore/util/totp/UriTotpFinderTest.kt b/format/common/src/test/kotlin/app/passwordstore/util/totp/UriTotpFinderTest.kt
new file mode 100644
index 00000000..e462c490
--- /dev/null
+++ b/format/common/src/test/kotlin/app/passwordstore/util/totp/UriTotpFinderTest.kt
@@ -0,0 +1,55 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package app.passwordstore.util.totp
+
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class UriTotpFinderTest {
+
+  private val totpFinder = UriTotpFinder()
+
+  @Test
+  fun findSecret() {
+    assertEquals("HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ", totpFinder.findSecret(TOTP_URI))
+    assertEquals(
+      "HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ",
+      totpFinder.findSecret("name\npassword\ntotp: HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ")
+    )
+    assertEquals("HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ", totpFinder.findSecret(PASS_FILE_CONTENT))
+  }
+
+  @Test
+  fun findDigits() {
+    assertEquals("12", totpFinder.findDigits(TOTP_URI))
+    assertEquals("12", totpFinder.findDigits(PASS_FILE_CONTENT))
+  }
+
+  @Test
+  fun findPeriod() {
+    assertEquals(25, totpFinder.findPeriod(TOTP_URI))
+    assertEquals(25, totpFinder.findPeriod(PASS_FILE_CONTENT))
+  }
+
+  @Test
+  fun findAlgorithm() {
+    assertEquals("SHA256", totpFinder.findAlgorithm(TOTP_URI))
+    assertEquals("SHA256", totpFinder.findAlgorithm(PASS_FILE_CONTENT))
+  }
+
+  @Test
+  fun findIssuer() {
+    assertEquals("ACME Co", totpFinder.findIssuer(TOTP_URI))
+    assertEquals("ACME Co", totpFinder.findIssuer(PASS_FILE_CONTENT))
+  }
+
+  companion object {
+
+    const val TOTP_URI =
+      "otpauth://totp/ACME%20Co:john@example.com?secret=HXDMVJECJJWSRB3HWIZR4IFUGFTMXBOZ&issuer=ACME%20Co&algorithm=SHA256&digits=12&period=25"
+    const val PASS_FILE_CONTENT = "password\n$TOTP_URI"
+  }
+}