diff --git a/kmp-advcrypto/src/linuxX64Main/kotlin/io/karma/advcrypto/linux/providers/OpenSSLCryptoProvider.kt b/kmp-advcrypto/src/linuxX64Main/kotlin/io/karma/advcrypto/linux/providers/OpenSSLCryptoProvider.kt
index 92f2857..df3ba61 100644
--- a/kmp-advcrypto/src/linuxX64Main/kotlin/io/karma/advcrypto/linux/providers/OpenSSLCryptoProvider.kt
+++ b/kmp-advcrypto/src/linuxX64Main/kotlin/io/karma/advcrypto/linux/providers/OpenSSLCryptoProvider.kt
@@ -14,17 +14,25 @@
  * limitations under the License.
  */
 
+@file:OptIn(ExperimentalForeignApi::class)
+
 package io.karma.advcrypto.linux.providers
 
 import io.karma.advcrypto.AbstractProvider
 import io.karma.advcrypto.Providers
+import io.karma.advcrypto.algorithm.BlockMode
+import io.karma.advcrypto.algorithm.delegates.CipherDelegate
 import io.karma.advcrypto.algorithm.delegates.KeyGenContext
+import io.karma.advcrypto.annotations.InsecureCryptoApi
 import io.karma.advcrypto.keys.Key
 import io.karma.advcrypto.keys.KeyPair
 import io.karma.advcrypto.keys.enum.KeyType
 import io.karma.advcrypto.linux.keys.OpenSSLKey
 import io.karma.advcrypto.linux.keys.OpenSSLPKey
+import io.karma.advcrypto.linux.utils.KeyReaderHelper
 import io.karma.advcrypto.linux.utils.SecureHeap
+import kotlinx.cinterop.ByteVar
+import kotlinx.cinterop.CPointer
 import kotlinx.cinterop.CValuesRef
 import kotlinx.cinterop.ExperimentalForeignApi
 import kotlinx.cinterop.UIntVar
@@ -39,9 +47,16 @@ import kotlinx.cinterop.value
 import libssl.BN_free
 import libssl.BN_new
 import libssl.BN_set_word
+import libssl.EVP_CIPHER
+import libssl.EVP_CIPHER_CTX
+import libssl.EVP_CIPHER_CTX_ctrl
+import libssl.EVP_CIPHER_CTX_new
+import libssl.EVP_CTRL_GCM_SET_IVLEN
+import libssl.EVP_DecryptInit_ex
 import libssl.EVP_DigestFinal
 import libssl.EVP_DigestInit
 import libssl.EVP_DigestUpdate
+import libssl.EVP_EncryptInit_ex
 import libssl.EVP_MAX_MD_SIZE
 import libssl.EVP_MD
 import libssl.EVP_MD_CTX_free
@@ -49,6 +64,18 @@ import libssl.EVP_MD_CTX_new
 import libssl.EVP_PKEY_free
 import libssl.EVP_PKEY_new
 import libssl.EVP_PKEY_set1_RSA
+import libssl.EVP_aes_128_cbc
+import libssl.EVP_aes_128_ctr
+import libssl.EVP_aes_128_ecb
+import libssl.EVP_aes_128_gcm
+import libssl.EVP_aes_192_cbc
+import libssl.EVP_aes_192_ctr
+import libssl.EVP_aes_192_ecb
+import libssl.EVP_aes_192_gcm
+import libssl.EVP_aes_256_cbc
+import libssl.EVP_aes_256_ctr
+import libssl.EVP_aes_256_ecb
+import libssl.EVP_aes_256_gcm
 import libssl.EVP_md5
 import libssl.EVP_sha1
 import libssl.EVP_sha224
@@ -65,6 +92,75 @@ import libssl.RSA_free
 import libssl.RSA_generate_key_ex
 import libssl.RSA_new
 
+data class BlockCipherContext(
+    val encryptCipher: CPointer<EVP_CIPHER_CTX>,
+    val decryptCipher: CPointer<EVP_CIPHER_CTX>,
+    val cipherType: CPointer<EVP_CIPHER>,
+   // val keyBuffer: CPointer<ByteVar>,
+    val blockMode: BlockMode
+)
+
+/**
+ * This method creates the method delegates for a default OpenSSL-based Cipher for a algorithm
+ * provider. This is used for AES etc.
+ */
+@OptIn(InsecureCryptoApi::class)
+fun CipherDelegate<BlockCipherContext>.initializeSymmetricOpenSSLBlockCipher(
+    secureHeap: SecureHeap,
+    defaultBlockMode: BlockMode
+) {
+    initializer { spec, key ->
+        // TODO: If key format is not BINARY, derive key encoding to BINARY
+        val bitSize = KeyReaderHelper.readKeySizeInBits(key)
+        //val keyBuffer = checkNotNull(secureHeap.allocate((bitSize / 8).toULong()))
+        // TODO: Write encoded key securely into key buffer
+
+        val blockMode = spec.blockMode?: defaultBlockMode
+        val cipherType = checkNotNull(when(blockMode) {
+            BlockMode.GCM -> when(bitSize) {
+                128 -> EVP_aes_128_gcm()
+                192 -> EVP_aes_192_gcm()
+                256 -> EVP_aes_256_gcm()
+                else -> throw IllegalArgumentException("AES-$blockMode-$bitSize is not supported")
+            }
+            BlockMode.CTR -> when(bitSize) {
+                128 -> EVP_aes_128_ctr()
+                192 -> EVP_aes_192_ctr()
+                256 -> EVP_aes_256_ctr()
+                else -> throw IllegalArgumentException("AES-$blockMode-$bitSize is not supported")
+            }
+            BlockMode.CBC -> when(bitSize) {
+                128 -> EVP_aes_128_cbc()
+                192 -> EVP_aes_192_cbc()
+                256 -> EVP_aes_256_cbc()
+                else -> throw IllegalArgumentException("AES-$blockMode-$bitSize is not supported")
+            }
+            BlockMode.ECB -> when(bitSize) {
+                128 -> EVP_aes_128_ecb()
+                192 -> EVP_aes_192_ecb()
+                256 -> EVP_aes_256_ecb()
+                else -> throw IllegalArgumentException("AES-$blockMode-$bitSize is not supported")
+            }
+        })
+
+        val encryptCipherContext = checkNotNull(EVP_CIPHER_CTX_new()).apply {
+            EVP_EncryptInit_ex(this, cipherType, null, null, null)
+            if (blockMode == BlockMode.GCM) {
+                EVP_CIPHER_CTX_ctrl(this, EVP_CTRL_GCM_SET_IVLEN, 16, null)
+            }
+        }
+
+        val decryptCipherContext = checkNotNull(EVP_CIPHER_CTX_new()).apply {
+            EVP_DecryptInit_ex(this, cipherType, null, null, null)
+            if (blockMode == BlockMode.GCM) {
+                EVP_CIPHER_CTX_ctrl(this, EVP_CTRL_GCM_SET_IVLEN, 16, null)
+            }
+        }
+
+        BlockCipherContext(encryptCipherContext, decryptCipherContext, cipherType, blockMode)
+    }
+}
+
 class OpenSSLCryptoProvider: AbstractProvider(
     "Default",
     "This class provides access to the default asymmetric and symmetric algorithms on Linux",
@@ -118,6 +214,9 @@ class OpenSSLCryptoProvider: AbstractProvider(
         openSSLHasher("SHA3-512", EVP_sha3_512())
 
         algorithm(providers, "AES") {
+            allowedBlockModes = BlockMode.entries.toTypedArray()
+            defaultBlockMode = BlockMode.GCM
+
             keyGenerator<Unit>(Key.PURPOSES_SYMMETRIC, arrayOf(128, 196, 256), 256) {
                 initializer { spec -> KeyGenContext(spec, Unit) }
                 generateKey { context ->
@@ -130,6 +229,10 @@ class OpenSSLCryptoProvider: AbstractProvider(
                     )
                 }
             }
+
+            cipher {
+                initializeSymmetricOpenSSLBlockCipher(secureHeap, defaultBlockMode!!)
+            }
         }
 
         algorithm(providers, "RSA") {