From 355e5dcdede7ae432990cd01e48db7f0c837de8a Mon Sep 17 00:00:00 2001
From: David Michael <david@zeet.co>
Date: Sun, 18 Jun 2017 18:46:39 +0100
Subject: [PATCH 1/2] Added key derivation

---
 cryptokdf/crypto_kdf.go | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 cryptokdf/crypto_kdf.go

diff --git a/cryptokdf/crypto_kdf.go b/cryptokdf/crypto_kdf.go
new file mode 100644
index 0000000..bf9ac31
--- /dev/null
+++ b/cryptokdf/crypto_kdf.go
@@ -0,0 +1,44 @@
+package cryptokdf
+
+// #cgo pkg-config: libsodium
+// #include <stdlib.h>
+// #include <sodium.h>
+import "C"
+import "github.com/GoKillers/libsodium-go/support"
+
+func CryptoKdfKeybytes() int {
+	return int(C.crypto_kdf_keybytes())
+}
+
+func CryptoKdfContextbytes() int {
+	return int(C.crypto_kdf_contextbytes())
+}
+
+func CryptoKdfBytesMin() int {
+	return int(C.crypto_kdf_bytes_min())
+}
+
+func CryptoKdfBytesMax() int {
+	return int(C.crypto_kdf_bytes_max())
+}
+
+func CryptoKdfKeygen(k []byte) {
+	support.CheckSize(k, CryptoKdfKeybytes(), "keybytes")
+	C.crypto_kdf_keygen((*C.uchar)(&k[0]))
+}
+
+func CryptoKdfDeriveFromKey(l int, i uint64, c string, k []byte) ([]byte, int) {
+	support.CheckSize(k, CryptoKdfKeybytes(), "keybytes")
+	support.CheckSize([]byte(c), CryptoKdfContextbytes(), "contextbytes")
+	support.CheckSizeInRange(l, CryptoKdfBytesMin(), CryptoKdfBytesMax(), "subkey_len")
+	out := make([]byte, l)
+
+	exit := int(C.crypto_kdf_derive_from_key(
+		(*C.uchar)(&out[0]),
+		(C.size_t)(l),
+		(C.uint64_t)(i),
+		C.CString(c),
+		(*C.uchar)(&k[0])))
+
+	return out, exit
+}

From a0dd7f90ba821e9984acb8625ac0b132c94ff898 Mon Sep 17 00:00:00 2001
From: David Michael <david@zeet.co>
Date: Sun, 18 Jun 2017 19:12:42 +0100
Subject: [PATCH 2/2] Simplified CryptKdfKeygen

---
 cryptokdf/crypto_kdf.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/cryptokdf/crypto_kdf.go b/cryptokdf/crypto_kdf.go
index bf9ac31..660150c 100644
--- a/cryptokdf/crypto_kdf.go
+++ b/cryptokdf/crypto_kdf.go
@@ -22,9 +22,10 @@ func CryptoKdfBytesMax() int {
 	return int(C.crypto_kdf_bytes_max())
 }
 
-func CryptoKdfKeygen(k []byte) {
-	support.CheckSize(k, CryptoKdfKeybytes(), "keybytes")
+func CryptoKdfKeygen() []byte {
+	k := make([]byte, CryptoKdfKeybytes())
 	C.crypto_kdf_keygen((*C.uchar)(&k[0]))
+	return k
 }
 
 func CryptoKdfDeriveFromKey(l int, i uint64, c string, k []byte) ([]byte, int) {