From e335b91ccd6175f43d8bb0c2ea4811e49cb4d95b Mon Sep 17 00:00:00 2001
From: Harald Welte <laforge@gnumonks.org>
Date: Wed, 30 Jun 2010 19:50:14 +0200
Subject: [PATCH] GPRS: Add 'input' generator functions for GPRS cipher
 algorithm

---
 include/osmocom/crypt/gprs_cipher.h |  6 ++++++
 src/gprs_cipher_core.c              | 14 ++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/include/osmocom/crypt/gprs_cipher.h b/include/osmocom/crypt/gprs_cipher.h
index 165603764..3e514ec7f 100644
--- a/include/osmocom/crypt/gprs_cipher.h
+++ b/include/osmocom/crypt/gprs_cipher.h
@@ -45,4 +45,10 @@ int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
 /* Do we have an implementation for this cipher? */
 int gprs_cipher_supported(enum gprs_ciph_algo algo);
 
+/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
+uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc);
+
+/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
+uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc);
+
 #endif /* _GPRS_CIPHER_H */
diff --git a/src/gprs_cipher_core.c b/src/gprs_cipher_core.c
index a72dda846..6174bd727 100644
--- a/src/gprs_cipher_core.c
+++ b/src/gprs_cipher_core.c
@@ -83,3 +83,17 @@ int gprs_cipher_supported(enum gprs_ciph_algo algo)
 
 	return 0;
 }
+
+/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
+uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc)
+{
+	uint32_t sx = ((1<<27) * sapi) + (1<<31);
+
+	return (iov_ui ^ sx) + lfn + oc;
+}
+
+/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
+uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc)
+{
+	return iov_i + lfn + oc;
+}