diff --git a/src/crypto.zig b/src/crypto.zig
index 4fa74f6..83abb09 100644
--- a/src/crypto.zig
+++ b/src/crypto.zig
@@ -1,3 +1,7 @@
+// WARNING NOT FUNCTIONAL !!!
+// This is just a draft
+// TODO
+
 ///////////////// Imports
 //
 
@@ -69,5 +73,5 @@ test "AES encryption defaults" {
     var data = [_]u8{ 1, 2, 3, 4 };
     const key = [_]u8{ 1, 2, 3, 4 };
     const iv = [_]u8{ 1, 2, 3, 4 };
-    crypto.aes_cbc256.encrypt(&data, &key, &iv);
+    crypto.Aes.CBC_265.encrypt(&data, &key, &iv);
 }
diff --git a/src/crypto/aes.zig b/src/crypto/aes.zig
index aceb2c9..df886b2 100644
--- a/src/crypto/aes.zig
+++ b/src/crypto/aes.zig
@@ -9,7 +9,7 @@ pub const CBC256_Implementation = struct {
 };
 
 // TODO
-pub const CBC256_DefaultImplementation = struct {
+pub const CBC265_DefaultImplementation = struct {
 
     // Zig stdlib seems to provide no support for AES CBC265
     // It may need some custom implementation or another library
diff --git a/src/crypto/hkdf.zig b/src/crypto/hkdf.zig
index 05a93a8..f1e9458 100644
--- a/src/crypto/hkdf.zig
+++ b/src/crypto/hkdf.zig
@@ -1,29 +1,9 @@
 pub const Implementation = struct {
     
-     prk_length: comptime_int,
-
-     expand: *const fn (out: []u8, ctx: []const u8, prk: *[Implementation.prk_length]u8) void,
-     extract: *const fn (out: *[Implementation.prk_length]u8, salt: []const u8, ikm: []const u8) void,
-
 };
 
 pub const defaultImplementation = struct {
     
-    const Sha256 = @import("std").crypto.hash.sha2.Sha256;
-
-    const HashImpl = Sha256;
-    const HmacImpl = @import("std").crypto.auth.hmac.Hmac(HashImpl);
-
-    const Hkdf = @import("std").crypto.kdf.hkdf.Hkdf(HmacImpl);
-
-    pub const prk_length = Hkdf.prk_length;
-
-    pub fn expand(out: []u8, ctx: []const u8, prk: *[prk_length]u8) void {
-        Hkdf.expand(out, ctx, prk);
-    }
-
-    pub fn extract(out: *[prk_length]u8, salt: []const u8, ikm: []const u8) void {
-        out *= Hkdf.extract(salt, ikm);
-    }
+    const Hkdf = @import("std").crypto.kdf.hkdf.Hkdf;
 
 };
diff --git a/src/crypto/hmac.zig b/src/crypto/hmac.zig
index 131bb20..cb096e8 100644
--- a/src/crypto/hmac.zig
+++ b/src/crypto/hmac.zig
@@ -1,20 +1,15 @@
 pub const Implementation = struct {
     
-    mac_length: comptime_int,
-    
-    create: *const fn (out: *[Implementation.mac_length]u8, msg: []const u8, key: []const u8) void,
 };
 
 pub const defaultImplementation = struct {
     
-    const Sha256 = @import("std").crypto.hash.sha2.Sha256;
+    const Hmac = @import("std").crypto.auth.hmac.Hmac;
 
-    const HashImpl = Sha256;
-    const Hmac = @import("std").crypto.auth.hmac.Hmac(Sha256);
-
-    pub const mac_length = Hmac.mac_length;
-
-    pub fn create(out: *[mac_length]u8, msg: []const u8, key: []const u8) void {
-        Hmac.create(out, msg, key);
+    pub fn create(out: []u8, msg: []const u8, key: []const u8) !void {
+        _ = out;
+        _ = msg;
+        _ = key;
+        return error.NotImplemented;
     }
 };
diff --git a/src/crypto/sha256.zig b/src/crypto/sha256.zig
index 0d913a1..70478e0 100644
--- a/src/crypto/sha256.zig
+++ b/src/crypto/sha256.zig
@@ -1,17 +1,18 @@
 pub const Implementation = struct {
     
-    hash_length: comptime_int,
-
-    hash: *const fn (buffer: []const u8, out: *[Implementation.hash_length]u8) void,
+    hash: *const fn (buffer: []const u8, out: []u8) void,
 };
 
 pub const defaultImplementation = struct {
     
     const Sha256 = @import("std").crypto.hash.sha2.Sha256;
 
-    pub const hash_len = Sha256.digest_length;
+    const HASH_LEN = 32; // In bytes
 
-    pub fn hash(buffer: []const u8, out: *[hash_len]u8) !void {
+    pub fn hash(buffer: []const u8, out: []u8) !void {
+        if (out.len < HASH_LEN) {
+            return error.BufferTooShort;
+        }
         Sha256.hash(buffer, out, .{});
     }
 };