EncryptImpl: Emit session-key

pgpainless-core/src/main/kotlin/org/pgpainless/encryption_signing/EncryptionResult.kt

@@ -17,9 +17,11 @@ import org.pgpainless.algorithm.SymmetricKeyAlgorithm
 import org.pgpainless.bouncycastle.extensions.matches
 import org.pgpainless.key.SubkeyIdentifier
 import org.pgpainless.util.MultiMap
+import org.pgpainless.util.SessionKey
 
 data class EncryptionResult(
     val encryptionMechanism: MessageEncryptionMechanism,
+    val sessionKey: SessionKey?,
     val compressionAlgorithm: CompressionAlgorithm,
     val detachedDocumentSignatures: OpenPGPSignatureSet<OpenPGPDocumentSignature>,
     val recipients: Set<SubkeyIdentifier>,
@@ -84,6 +86,7 @@ data class EncryptionResult(
         private var _fileName = ""
         private var _modificationDate = Date(0)
         private var _encoding = StreamEncoding.BINARY
+        private var _sessionKey: SessionKey? = null
 
         fun setEncryptionMechanism(mechanism: MessageEncryptionMechanism): Builder = apply {
             _encryptionMechanism = mechanism
@@ -105,6 +108,8 @@ data class EncryptionResult(
             (recipients as MutableSet).add(recipient)
         }
 
+        fun setSessionKey(sessionKey: SessionKey) = apply { _sessionKey = sessionKey }
+
         fun addDetachedSignature(signature: OpenPGPDocumentSignature): Builder = apply {
             detachedSignatures.add(signature)
         }
@@ -114,6 +119,7 @@ data class EncryptionResult(
 
             return EncryptionResult(
                 _encryptionMechanism,
+                _sessionKey,
                 _compressionAlgorithm!!,
                 OpenPGPSignatureSet(detachedSignatures),
                 recipients,

pgpainless-core/src/main/kotlin/org/pgpainless/encryption_signing/EncryptionStream.kt

@@ -20,6 +20,7 @@ import org.pgpainless.algorithm.CompressionAlgorithm
 import org.pgpainless.algorithm.StreamEncoding
 import org.pgpainless.bouncycastle.extensions.pgpDataEncryptorBuilder
 import org.pgpainless.util.ArmoredOutputStreamFactory
+import org.pgpainless.util.SessionKey
 
 // 1 << 8 causes wrong partial body length encoding
 //  1 << 9 fixes this.
@@ -93,6 +94,11 @@ class EncryptionStream(
         options.encryptionOptions.encryptionKeyIdentifiers.forEach { r ->
             resultBuilder.addRecipient(r)
         }
+        encryptedDataGenerator.setSessionKeyExtractionCallback { pgpSessionKey ->
+            if (pgpSessionKey != null) {
+                resultBuilder.setSessionKey(SessionKey(pgpSessionKey))
+            }
+        }
 
         publicKeyEncryptedStream =
             encryptedDataGenerator.open(outermostStream, ByteArray(BUFFER_SIZE)).also { stream ->

pgpainless-sop/src/main/kotlin/org/pgpainless/sop/EncryptImpl.kt

@@ -26,6 +26,7 @@ import org.pgpainless.util.Passphrase
 import sop.EncryptionResult
 import sop.Profile
 import sop.ReadyWithResult
+import sop.SessionKey
 import sop.enums.EncryptAs
 import sop.exception.SOPGPException
 import sop.operation.Encrypt
@@ -98,8 +99,10 @@ class EncryptImpl(private val api: PGPainless) : Encrypt {
                         api.generateMessage().onOutputStream(outputStream).withOptions(options)
                     Streams.pipeAll(plaintext, encryptionStream)
                     encryptionStream.close()
-                    // TODO: Extract and emit session key once BC supports that
+                    return EncryptionResult(
-                    return EncryptionResult(null)
+                        encryptionStream.result.sessionKey?.let {
+                            SessionKey(it.algorithm.algorithmId.toByte(), it.key)
+                        })
                 }
             }
         } catch (e: PGPException) {