Container started

src/commonMain/kotlin/net/sergeych/crypto2/Asymmetric.kt

@@ -7,6 +7,7 @@ import com.ionspin.kotlin.crypto.scalarmult.ScalarMultiplication
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.Transient
 import net.sergeych.bipack.BipackDecoder
+import net.sergeych.bipack.BipackEncoder
 import net.sergeych.crypto2.Asymmetric.Message
 import net.sergeych.crypto2.Asymmetric.PublicKey
 import net.sergeych.crypto2.Asymmetric.SecretKey
@@ -32,7 +33,7 @@ object Asymmetric {
     /**
      * Encrypted message holder.
      *
-     * Do not instantiate it directly, use [SecretKey.encrypt], [PublicKey.encryptAnonymously] or [createMessage]
+     * Do not instantiate it directly, use [PublicKey.encryptMessage], [PublicKey.encryptAnonymousMessage], etc.
      * instead. Also [SecretKey.decrypt] can be used to decrypt it same as [decrypt] or [decryptWithSenderKey].
      *
      * To successfully decrypt the message, it is necessary to know a sender public key, and non-secret nonce.
@@ -42,13 +43,12 @@ object Asymmetric {
     class Message(
         private val nonce: UByteArray,
         private val encryptedMessage: UByteArray,
-        val senderPublicKey: PublicKey? = null,
+        val senderPublicKey: PublicKey,
     ) {
         /**
          * Decrypt the message, same as [SecretKey.decrypt]
          */
         fun decrypt(recipientKey: SecretKey): UByteArray {
-            check(senderPublicKey != null)
             return decryptWithSenderKey(senderPublicKey, recipientKey)
         }
 
@@ -58,11 +58,15 @@ object Asymmetric {
          */
         fun decryptWithSenderKey(senderKey: PublicKey, recipientKey: SecretKey): UByteArray {
             return try {
-                Box.openEasy(encryptedMessage, nonce, senderKey.keyBytes, recipientKey.keyBytes)
+                WithFill.decode(
+                    Box.openEasy(encryptedMessage, nonce, senderKey.keyBytes, recipientKey.keyBytes)
+                )
             } catch (_: BoxCorruptedOrTamperedDataException) {
                 throw DecryptionFailedException()
             }
         }
+
+        val encoded: UByteArray by lazy { BipackEncoder.encode(this).toUByteArray() }
     }
 
     /**
@@ -72,30 +76,27 @@ object Asymmetric {
      * The authenticated encryption is used, is the message _is successfully decrypted_, it also means that
      * it was signed by the sender, whose public key is known at the decryption time.
      *
-     * When it is important not to provide senders' key, use [PublicKey.encryptAnonymously].
+     * When it is important not to provide senders' key, use [PublicKey.encryptAnonymousMessage].
      *
      * @param from the senders' secret key.
      * @param recipient the recipients' public key.
      * @param plainData data to encrypt
-     * @param excludeSenderKey if set to true, senders' public key will not be included in the message.
-     *      In this case, the recipient must know it from other sources to be able to decrypt the message.
      */
-    fun createMessage(
+    private fun createMessage(
         from: SecretKey, recipient: PublicKey, plainData: UByteArray,
-        excludeSenderKey: Boolean = false,
+        nonce: UByteArray = randomNonce(),
     ): Message {
-        val nonce = randomNonce()
         return Message(
             nonce,
             Box.easy(plainData, nonce, recipient.keyBytes, from.keyBytes),
-            if (excludeSenderKey) null else from.publicKey
+            from.publicKey
         )
     }
 
     /**
      * The generated key pair. See [generateKeys]
      */
-    data class KeyPair(val secretKey: SecretKey, val senderKey: PublicKey)
+    data class KeyPair(val secretKey: SecretKey, val publicKey: PublicKey)
 
     /**
      * Generate a new random pair of public and secret keys.
@@ -114,11 +115,18 @@ object Asymmetric {
     val nonceBytesLength = crypto_box_NONCEBYTES
 
     /**
-     * The public key used as the recipient for [Message] (see [SecretKey.encrypt], etc.). It also
-     * could be used to encrypt anonymous messages with [encryptAnonymously]
+     * The public key: [encryptMessage] so only a secret key owner can read it. Allows
+     * anonymous [encryptAnonymousMessage] and signed [encryptMessage] encryption.
+     *
+     * Anonymous encryption is very slow in comparison.
      */
     @Serializable
     class PublicKey(val keyBytes: UByteArray) {
+
+        val tag: KeyTag by lazy {
+            KeyTag(KeysMagickNumbers.defaultAssymmetric, blake2b(keyBytes))
+        }
+
         override fun equals(other: Any?): Boolean {
             if (this === other) return true
             if (other !is PublicKey) return false
@@ -126,19 +134,57 @@ object Asymmetric {
             return keyBytes contentEquals other.keyBytes
         }
 
+        override fun hashCode(): Int {
+            return keyBytes.hashCode()
+        }
+
         /**
          * Create an anonymous message that could be decrypted only with the [SecretKey] that corresponds this.
          * Anonymous message uses one-time secret key, the public part of which is included into the
          * [Message], so the sender could not be identified.
+         *
+         * __Anonymous encryption is much slower__ as it generates new keys every time, use [encryptMessage]
+         * when possible
+         *
          * The authentication is used despite the anonymity, and the fact of the successful decryption
          * proves that the message was not altered after creation.
          */
-        fun encryptAnonymously(plainData: UByteArray): Message =
-            createMessage(generateKeys().secretKey, this, plainData)
+        fun encryptAnonymousMessage(plainData: UByteArray, randomFill: IntRange? = null): Message =
+            encryptMessage(plainData,randomFill=randomFill)
+
+        /**
+         * Anonymous encryption, see [encryptAnonymousMessage], to binary data. Sender could not be identified.
+         */
+        @Suppress("unused")
+        fun encrypt(plainData: UByteArray, randomFill: IntRange? = null): UByteArray =
+            encryptMessage(plainData, randomFill = randomFill).encoded
+
+        /**
+         * Universal public-key encryption. Note that message authenticity is guaranteed if the decryption is successful
+         * whether [senderKey] is provider, the latter only allow to positively identify the sender.
+         *
+         * @param plainData data to encrypt
+         * @param nonce allows specifying exact nonce, default to random (safe)
+         * @param senderKey key to authenticate sending party. It is safe and much faster to specify it,
+         *      otherwise an anonymous key will be created for each encryption, also safe and anonymous, but slow.
+         */
+        fun encryptMessage(
+            plainData: UByteArray,
+            nonce: UByteArray = randomNonce(),
+            senderKey: SecretKey = randomSecretKey(),
+            randomFill: IntRange? = null,
+        ) = createMessage(senderKey, this, WithFill.encode(plainData, randomFill), nonce)
+
+        /**
+         * Encrypt message using the specified secret key as sender authentication. Recipient, the party having
+         * [SecretKey] corresponding to this one, will be able to decrypt the message and be sure that [senderKey]
+         * was the author and the message was not altered.
+         */
+        fun encryptMessage(plainData: UByteArray,
+                           senderKey: SecretKey,
+                           randomFill: IntRange? = null): Message =
+            createMessage(senderKey, this, WithFill.encode(plainData, randomFill))
 
-        override fun hashCode(): Int {
-            return keyBytes.hashCode()
-        }
     }
 
     /**
@@ -151,19 +197,10 @@ object Asymmetric {
         val _cachedPublicKey: PublicKey? = null,
     ) : DecryptingKey {
 
-        /**
-         * Encrypt the message for [recipient]. The [Message] will include the our [publicKey]
-         * and thus ready to be decrypted.
-         *
-         * The message is authenticated by this secret key.
-         */
-        fun encrypt(plainData: UByteArray, recipient: PublicKey): Message =
-            createMessage(this, recipient, plainData)
-
         /**
          * Decrypt with authentication checks the message which must have [Message.senderPublicKey] set.
          * Use [decryptWithSenderKey] otherwise. Note that the authenticated encryption is always use, even if
-         * the [PublicKey.encryptAnonymously] was used to create a message, if it is successfully decrypted,
+         * the [PublicKey.encryptAnonymousMessage] was used to create a message, if it is successfully decrypted,
          * it is guaranteed that the message was not altered after creation.
          *
          * @throws DecryptionFailedException If the message is tampered (changed after creation) or was not intended for us,
@@ -213,9 +250,7 @@ object Asymmetric {
             return message.decrypt(this)
         }
 
-        override val decryptingTag: KeyTag by lazy {
-            KeyTag(KeysMagickNumbers.defaultAssymmetric, blake2b(publicKey.keyBytes))
-        }
+        override val tag: KeyTag by lazy { publicKey.tag }
 
         override val nonceBytesLength: Int
             get() = 0

src/commonMain/kotlin/net/sergeych/crypto2/Container.kt

@@ -1,9 +1,148 @@
-//package net.sergeych.crypto2
-//
-//import kotlinx.serialization.Serializable
-//
-//@Serializable
-//sealed class Container {
+package net.sergeych.crypto2
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.Transient
+import net.sergeych.bipack.BipackDecoder
+import net.sergeych.bipack.BipackEncoder
+
+/*
+The problem with container is the following. When we encrypt it with asymmetric key,
+we provide public key as the recipient. But public key alone is not effective
+as it is restricted to anonymous encryption which is very slow.
+
+We might need an alternative to specify the (sender key,recipient key) pair also. We need a good
+solution for it.
+
+ */
+
+
+@Serializable
+sealed class Container {
+
+    class InvalidContainerException : Crypto2Exception("the container is invalid")
+
+    abstract fun decryptWith(keyRing: UniversalRing): UByteArray?
+
+    fun decryptWith(vararg decryptingKeys: DecryptingKey): UByteArray? =
+        decryptWith(UniversalRing(*decryptingKeys))
+
+    @Transient
+    var decryptedData: UByteArray? = null
+
+    val isDecrypted: Boolean get() = decryptedData != null
+
+    @Serializable
+    @SerialName("1")
+    class Single(val keyTag: KeyTag, val encryptedMessage: UByteArray) : Container() {
+        override fun decryptWith(keyRing: UniversalRing): UByteArray? {
+            decryptedData?.let { return it }
+            for (k in keyRing) {
+                if (k.tag == keyTag) {
+                    kotlin.runCatching { k.decrypt(encryptedMessage) }.getOrNull()?.let {
+                        decryptedData = it
+                        return it
+                    }
+                }
+            }
+            return null
+        }
+    }
+
+    @Serializable
+    @SerialName("*")
+    class Multi(val encryptedKeys: List<EncryptedKey>, val encryptedMessage: UByteArray) : Container() {
+        @Serializable
+        class EncryptedKey(val tag: KeyTag, val cipherData: UByteArray)
+
+        private var mainKey: SymmetricKey? = null
+
+        override fun decryptWith(keyRing: UniversalRing): UByteArray? {
+            decryptedData?.let { return it }
+            for (key in keyRing) {
+                val tag = key.tag
+                for (encryptedKey in encryptedKeys) {
+                    if (tag == encryptedKey.tag) {
+                        kotlin.runCatching {
+                            BipackDecoder.decode<SymmetricKey>(
+                                key.decrypt(encryptedKey.cipherData).toByteArray()
+                            )
+                        }.getOrNull()?.let { k ->
+                            if (kotlin.runCatching { decryptedData = k.decrypt(encryptedKey.cipherData) }.isFailure)
+                                throw InvalidContainerException()
+                            mainKey = k
+                        }
+                        if (decryptedData != null) return decryptedData
+                    }
+                }
+            }
+            return null
+        }
+    }
+
+
+    val encoded: UByteArray by lazy {
+        BipackEncoder.encode(this).toUByteArray()
+    }
+
+    companion object {
+
+        class Builder internal constructor(private val plainData: UByteArray) {
+            private val plainKeys = mutableListOf<EncryptingKey>()
+            private val keyPairs = mutableListOf<Pair<Asymmetric.SecretKey?,Asymmetric.PublicKey>>()
+            private var fillRange: IntRange? = null
+
+            fun key(vararg keys: EncryptingKey) { plainKeys.addAll(keys) }
+
+            fun key(vararg pairs: Pair<Asymmetric.SecretKey,Asymmetric.PublicKey>) {
+                keyPairs.addAll(pairs)
+            }
+
+            fun key(vararg publicKeys: Asymmetric.PublicKey) {
+                keyPairs.addAll(publicKeys.map { null to it })
+            }
+
+            @Suppress("unused")
+            fun fill(range: IntRange) {
+                require(range.first >= 0 ) { "range must be positive"}
+                fillRange = range
+            }
+
+            fun build(): Container {
+                return when( plainKeys.size + keyPairs.size ) {
+                    0 -> throw IllegalArgumentException("Container needs at least one key")
+                    1 -> {
+                        plainKeys.firstOrNull()?.let {
+                            Single(it.tag, it.encrypt(plainData, fillRange))
+                        } ?: run {
+                            val (sk, pk) = keyPairs.first()
+                            Single(pk.tag, pk.encryptMessage(plainData,
+                                senderKey = sk ?: Asymmetric.randomSecretKey(),
+                                randomFill = fillRange).encoded)
+                        }
+                    }
+                    else -> {
+                        TODO("multikey")
+                    }
+                }
+            }
+        }
+
+        fun create(plainData: UByteArray,builder: Builder.()->Unit) =
+            Builder(plainData).also { it.builder() }.build()
+
+        fun create(plainData: UByteArray, vararg keys: EncryptingKey): Container =
+            create(plainData) { key(*keys) }
+
+        fun create(plainData: UByteArray, vararg keys: Pair<Asymmetric.SecretKey,Asymmetric.PublicKey>) =
+            create(plainData) { key(*keys) }
+
+        fun decode(encoded: UByteArray): Container {
+            return BipackDecoder.decode(encoded.toByteArray())
+        }
+    }
+
+}
 //
 //
 //    /**

src/commonMain/kotlin/net/sergeych/crypto2/DecryptingKey.kt

@@ -28,7 +28,7 @@ interface DecryptingKey : NonceBased {
 
     fun decryptString(cipherData: UByteArray): String = decrypt(cipherData).decodeFromUByteArray()
 
-    val decryptingTag: KeyTag
+    val tag: KeyTag
 
 }
 

src/commonMain/kotlin/net/sergeych/crypto2/EncryptingKey.kt

@@ -27,7 +27,7 @@ interface EncryptingKey : NonceBased {
     fun encrypt(plainText: String,randomFill: IntRange? = null): UByteArray =
         encrypt(plainText.encodeToUByteArray(),randomFill)
 
-    val encryptingTag: KeyTag
+    val tag: KeyTag
 
     fun encryptWithNonce(plainData: UByteArray, nonce: UByteArray, randomFill: IntRange? = null): UByteArray
 }

src/commonMain/kotlin/net/sergeych/crypto2/SafeKeyExchange.kt

@@ -47,11 +47,14 @@ class SafeKeyExchange {
         @Suppress("unused")
         val sessionTag: UByteArray by lazy {
             if (!isClient)
-                blake2b(decryptingTag.tag + encryptingTag.tag)
+                blake2b(tag.tag + tag.tag)
             else
-                blake2b(encryptingTag.tag + decryptingTag.tag)
+                blake2b(tag.tag + tag.tag)
         }
 
+        override val tag: KeyTag
+            get() = if( isClient ) sendingKey.tag else receivingKey.tag
+
         override fun equals(other: Any?): Boolean {
             if (this === other) return true
             if (other !is SessionKey) return false

src/commonMain/kotlin/net/sergeych/crypto2/SymmetricKey.kt

@@ -3,8 +3,6 @@ package net.sergeych.crypto2
 import com.ionspin.kotlin.crypto.secretbox.SecretBox
 import com.ionspin.kotlin.crypto.secretbox.crypto_secretbox_NONCEBYTES
 import kotlinx.serialization.Serializable
-import net.sergeych.bipack.BipackDecoder
-import net.sergeych.bipack.BipackEncoder
 
 /**
  * Symmetric key implements authenticated encrypting with random nonce and optional fill.
@@ -32,36 +30,18 @@ class SymmetricKey(
         val nonce: UByteArray,
     )
 
-    /**
-     * @suppress
-     * add some random data to the end of the plain message
-     */
-    @Serializable
-    data class WithFill(
-        val data: UByteArray,
-        val safetyFill: UByteArray? = null,
-    )
-
     override fun encryptWithNonce(plainData: UByteArray, nonce: UByteArray, randomFill: IntRange?): UByteArray {
         require(nonce.size == nonceByteLength)
-
-        val fill = randomFill?.let {
-            require(it.start >= 0)
-            randomUBytes(randomInt(it))
-        }
-        val filled = BipackEncoder.encode(WithFill(plainData, fill))
-        return SecretBox.easy(filled.toUByteArray(), nonce, keyBytes)
+        return SecretBox.easy(WithFill.encode(plainData, randomFill), nonce, keyBytes)
     }
 
     override val nonceBytesLength: Int = nonceByteLength
 
-    override val encryptingTag by lazy { KeyTag(KeysMagickNumbers.defaultSymmetric,blake2b3l(keyBytes)) }
-    override val decryptingTag get() = encryptingTag
+    override val tag by lazy { KeyTag(KeysMagickNumbers.defaultSymmetric,blake2b3l(keyBytes)) }
 
     override fun decryptWithNonce(cipherData: UByteArray, nonce: UByteArray): UByteArray =
         protectDecryption {
-            BipackDecoder.decode<WithFill>(SecretBox.openEasy(cipherData, nonce, keyBytes).toByteArray())
-                .data
+            WithFill.decode(SecretBox.openEasy(cipherData, nonce, keyBytes))
         }
 
     override fun equals(other: Any?): Boolean {

src/commonMain/kotlin/net/sergeych/crypto2/UniversalKey.kt

@@ -7,7 +7,7 @@ import kotlinx.serialization.Transient
 @Serializable
 sealed class UniversalKey : DecryptingKey {
 
-    abstract val tag: KeyTag
+//    abstract val tag: KeyTag
 
 
 
@@ -15,7 +15,7 @@ sealed class UniversalKey : DecryptingKey {
     @SerialName("sy")
     data class Symmetric(val key: SymmetricKey) : UniversalKey(), EncryptingKey by key, DecryptingKey by key {
         @Transient
-        override val tag: KeyTag = key.encryptingTag
+        override val tag: KeyTag = key.tag
 
         @Transient
         override val nonceBytesLength: Int = key.nonceBytesLength
@@ -28,7 +28,7 @@ sealed class UniversalKey : DecryptingKey {
     data class Session(val key: SafeKeyExchange.SessionKey) : UniversalKey(), EncryptingKey by key,
         DecryptingKey by key {
         @Transient
-        override val tag: KeyTag = key.encryptingTag
+        override val tag: KeyTag = key.tag
         @Transient
         override val nonceBytesLength: Int = key.nonceBytesLength
     }
@@ -36,7 +36,7 @@ sealed class UniversalKey : DecryptingKey {
     @Serializable
     @SerialName("se")
     data class Secret(val key: Asymmetric.SecretKey) : UniversalKey(), DecryptingKey by key {
-        override val tag: KeyTag by lazy { key.decryptingTag }
+        override val tag: KeyTag by lazy { key.tag }
         override fun toString() = "U.Sec:$tag"
     }
 

src/commonMain/kotlin/net/sergeych/crypto2/UniversalRing.kt

@@ -8,6 +8,7 @@ class UniversalRing(
     private val keys: Collection<UniversalKey>
 ): Collection<UniversalKey> by keys {
     constructor(vararg keys: UniversalKey) : this(keys.toSet())
+    constructor(vararg keys: DecryptingKey) : this(keys.map { UniversalKey.from(it) }.toSet())
     @Transient
     val keySet = if( keys is Set<UniversalKey> ) keys else keys.toSet()
 

src/commonMain/kotlin/net/sergeych/crypto2/WithFill.kt

@@ -0,0 +1,37 @@
+package net.sergeych.crypto2
+
+import kotlinx.serialization.Serializable
+import net.sergeych.bipack.BipackDecoder
+import net.sergeych.bipack.BipackEncoder
+import net.sergeych.crypto2.WithFill.Companion.decode
+import net.sergeych.crypto2.WithFill.Companion.encode
+
+/**
+ * Utility class to optionally extend a message with random bytes added _before the message bytes_ that
+ * reduces chances to effective cryptanalysis from the first block. Use
+ * [encode] and [decode] to process filled data.
+ */
+@Serializable
+class WithFill private constructor(
+    @Suppress("unused")
+    val safetyFill: UByteArray = ubyteArrayOf(),
+    val data: UByteArray,
+) {
+    companion object {
+
+        /**
+         * Create binary data with specified fill
+         */
+        fun encode(data: UByteArray,range: IntRange? = null) =
+            BipackEncoder.encode(WithFill(range?.let {
+                require(range.first >= 0) { "range should not be negative" }
+                randomUBytes(randomInt(it))
+            } ?: ubyteArrayOf(), data)).toUByteArray()
+
+        /**
+         * extract binary data from filled
+         */
+        fun decode(data: UByteArray): UByteArray =
+            BipackDecoder.decode<WithFill>(data.toByteArray()).data
+    }
+}