From 042afe7fe73929f40b32545bbdd97f10f260af60 Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Wed, 21 Mar 2012 08:19:47 +0100
Subject: milenage: Add function to compute OPC from OP and K

---
 src/gsm/milenage/milenage.c | 15 +++++++++++++++
 src/gsm/milenage/milenage.h |  2 ++
 2 files changed, 17 insertions(+)

(limited to 'src/gsm/milenage')

diff --git a/src/gsm/milenage/milenage.c b/src/gsm/milenage/milenage.c
index cc4e95c5..b43f986a 100644
--- a/src/gsm/milenage/milenage.c
+++ b/src/gsm/milenage/milenage.c
@@ -327,3 +327,18 @@ int milenage_check(const u8 *opc, const u8 *k, const u8 *sqn, const u8 *_rand,
 
 	return 0;
 }
+
+int milenage_opc_gen(u8 *opc, const u8 *k, const u8 *op)
+{
+	int i;
+
+	/* Encrypt OP using K */
+	if (aes_128_encrypt_block(k, op, opc))
+		return -1;
+
+	/* XOR the resulting Ek(OP) with OP */
+	for (i = 0; i < 16; i++)
+		opc[i] = opc[i] ^ op[i];
+
+	return 0;
+}
diff --git a/src/gsm/milenage/milenage.h b/src/gsm/milenage/milenage.h
index d5054d6d..a91e946a 100644
--- a/src/gsm/milenage/milenage.h
+++ b/src/gsm/milenage/milenage.h
@@ -30,4 +30,6 @@ int milenage_f1(const u8 *opc, const u8 *k, const u8 *_rand,
 int milenage_f2345(const u8 *opc, const u8 *k, const u8 *_rand,
 		   u8 *res, u8 *ck, u8 *ik, u8 *ak, u8 *akstar);
 
+int milenage_opc_gen(u8 *opc, const u8 *k, const u8 *op);
+
 #endif /* MILENAGE_H */
-- 
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