Kotlin conversion: SessionKey

pgpainless-core/src/main/kotlin/org/pgpainless/util/SessionKey.kt

@@ -0,0 +1,48 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package org.pgpainless.util
+
+import org.bouncycastle.openpgp.PGPSessionKey
+import org.bouncycastle.util.encoders.Hex
+import org.pgpainless.algorithm.SymmetricKeyAlgorithm
+
+/**
+ * A [SessionKey] is the symmetric key that is used to encrypt/decrypt an OpenPGP message payload.
+ * The OpenPGP message header contains a copy of the session key, encrypted for the public key of each recipient.
+ *
+ * @param algorithm symmetric key algorithm
+ * @param key bytes of the key
+ */
+data class SessionKey(val algorithm: SymmetricKeyAlgorithm,
+        val key: ByteArray) {
+
+    /**
+     * Constructor to create a session key from a BC [PGPSessionKey] object.
+     *
+     * @param sessionKey BC session key
+     */
+    constructor(sessionKey: PGPSessionKey):
+            this(SymmetricKeyAlgorithm.requireFromId(sessionKey.algorithm), sessionKey.key)
+
+    override fun toString(): String {
+        return "${algorithm.algorithmId}:${Hex.toHexString(key)}"
+    }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+
+        other as SessionKey
+
+        if (algorithm != other.algorithm) return false
+        if (!key.contentEquals(other.key)) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        return 31 * algorithm.hashCode() + key.contentHashCode()
+    }
+}