Add `KeyPair` and `KeyManager` to manage keys in the app (#1487)

Co-authored-by: Harsh Shandilya <me@msfjarvis.dev>

3 files changed, 52 insertions, 0 deletions

diff --git a/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoException.kt b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoException.kt
new file mode 100644
index 00000000..6a73d381
--- /dev/null
+++ b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/CryptoException.kt
@@ -0,0 +1,19 @@
+package dev.msfjarvis.aps.data.crypto
+
+public sealed class CryptoException(message: String? = null) : Exception(message)
+
+public sealed class KeyPairException(message: String? = null) : CryptoException(message) {
+  public object PrivateKeyUnavailableException :
+    KeyPairException("Key object does not have a private sub-key")
+}
+
+public sealed class KeyManagerException(message: String? = null) : CryptoException(message) {
+  public object NoKeysAvailableException : KeyManagerException("No keys were found")
+  public object KeyDirectoryUnavailableException :
+    KeyManagerException("Key directory does not exist")
+  public object KeyDeletionFailedException : KeyManagerException("Couldn't delete the key file")
+  public class KeyNotFoundException(keyId: String) :
+    KeyManagerException("No key found with id: $keyId")
+  public class KeyAlreadyExistsException(keyId: String) :
+    KeyManagerException("Pre-existing key was found for $keyId but 'replace' is set to false")
+}
diff --git a/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyManager.kt b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyManager.kt
new file mode 100644
index 00000000..b5ba881e
--- /dev/null
+++ b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyManager.kt
@@ -0,0 +1,19 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.data.crypto
+
+import com.github.michaelbull.result.Result
+
+public interface KeyManager<T : KeyPair> {
+
+  public suspend fun addKey(key: T, replace: Boolean = false): Result<T, Throwable>
+  public suspend fun removeKey(key: T): Result<T, Throwable>
+  public suspend fun getKeyById(id: String): Result<T, Throwable>
+  public suspend fun getAllKeys(): Result<List<T>, Throwable>
+
+  /** Given a [fileName], return whether this instance can handle it. */
+  public fun canHandle(fileName: String): Boolean
+}
diff --git a/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyPair.kt b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyPair.kt
new file mode 100644
index 00000000..e2362612
--- /dev/null
+++ b/crypto-common/src/main/kotlin/dev/msfjarvis/aps/data/crypto/KeyPair.kt
@@ -0,0 +1,14 @@
+/*
+ * Copyright © 2014-2021 The Android Password Store Authors. All Rights Reserved.
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+package dev.msfjarvis.aps.data.crypto
+
+/** Defines expectations for a keypair used in public key cryptography. */
+public interface KeyPair {
+
+  public fun getPrivateKey(): ByteArray
+  public fun getPublicKey(): ByteArray
+  public fun getKeyId(): String
+}