Add GEA3 & GEA4 ciphers

Corresponding test code include both official test vectors from the
specs and data from over-the-air tests.

This obsoletes libosmo-crypt-a53 as it was last missing piece
unimplemented in libosmogsm.

Change-Id: I939e4f6b91b4a7c591ef3761fe2d46ed1c2fb2d3
Related: OS#1582

3 files changed, 110 insertions, 2 deletions

diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 781f153a..0f43f48a 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -24,10 +24,10 @@ libgsmint_la_SOURCES =  a5.c rxlev_stat.c tlv_parser.c comp128.c comp128v23.c \
 			conv_tch_afs_6_7_gen.c conv_tch_afs_5_9_gen.c \
 			conv_tch_afs_5_15_gen.c conv_tch_afs_4_75_gen.c \
 			auth_core.c auth_comp128v1.c auth_comp128v23.c \
-			auth_milenage.c milenage/aes-encblock.c \
+			auth_milenage.c milenage/aes-encblock.c gea.c \
 			milenage/aes-internal.c milenage/aes-internal-enc.c \
 			milenage/milenage.c gan.c ipa.c gsm0341.c apn.c \
-			gsup.c
+			gsup.c gprs_gea.c
 libgsmint_la_LDFLAGS = -no-undefined
 libgsmint_la_LIBADD = ../libosmocore.la
 
diff --git a/src/gsm/gea.c b/src/gsm/gea.c
new file mode 100644
index 00000000..b8f6768a
--- /dev/null
+++ b/src/gsm/gea.c
@@ -0,0 +1,60 @@
+/*
+ * gea.c
+ *
+ * Implementation of GEA3 and GEA4
+ *
+ * Copyright (C) 2016 by Sysmocom s.f.m.c. GmbH
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <osmocom/core/bits.h>
+#include <osmocom/crypt/gprs_cipher.h>
+#include <osmocom/crypt/auth.h>
+#include <osmocom/gsm/kasumi.h>
+
+#include <stdint.h>
+#include <string.h>
+
+/*! \brief Performs the GEA4 algorithm as in 3GPP TS 55.226 V9.0.0
+ *  \param[in,out] out Buffer for gamma for encrypted/decrypted
+ *  \param[in] len Length of out, in bytes
+ *  \param[in] kc Buffer with the ciphering key
+ *  \param[in] iv Init vector
+ *  \param[in] direct Direction: 0 (MS -> SGSN) or 1 (SGSN -> MS)
+ */
+int gea4(uint8_t *out, uint16_t len, uint8_t *kc, uint32_t iv,
+	 enum gprs_cipher_direction direction)
+{
+	_kasumi_kgcore(0xFF, 0, iv, direction, kc, out, len * 8);
+	return 0;
+}
+
+/*! \brief Performs the GEA3 algorithm as in 3GPP TS 55.216 V6.2.0
+ *  \param[in,out] out Buffer for gamma for encrypted/decrypted
+ *  \param[in] len Length of out, in bytes
+ *  \param[in] kc Buffer with the ciphering key
+ *  \param[in] iv Init vector
+ *  \param[in] direct Direction: 0 (MS -> SGSN) or 1 (SGSN -> MS)
+ */
+int gea3(uint8_t *out, uint16_t len, uint8_t *kc, uint32_t iv,
+	 enum gprs_cipher_direction direction)
+{
+	uint8_t ck[gprs_cipher_key_length(GPRS_ALGO_GEA4)];
+	osmo_c4(ck, kc);
+	return gea4(out, len, ck, iv, direction);
+}
diff --git a/src/gsm/gprs_gea.c b/src/gsm/gprs_gea.c
new file mode 100644
index 00000000..8ff16484
--- /dev/null
+++ b/src/gsm/gprs_gea.c
@@ -0,0 +1,48 @@
+/*
+ * gprs_gea.c
+ *
+ * GEA 3 & 4 plugin
+ *
+ * Copyright (C) 2016 by Sysmocom s.f.m.c. GmbH
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <osmocom/crypt/gprs_cipher.h>
+#include <osmocom/gsm/gea.h>
+
+#include <stdint.h>
+
+static struct gprs_cipher_impl gea3_impl = {
+	.algo = GPRS_ALGO_GEA3,
+	.name = "GEA3 (libosmogsm built-in)",
+	.priority = 100,
+	.run = &gea3,
+};
+
+static struct gprs_cipher_impl gea4_impl = {
+	.algo = GPRS_ALGO_GEA4,
+	.name = "GEA4 (libosmogsm built-in)",
+	.priority = 100,
+	.run = &gea4,
+};
+
+static __attribute__((constructor)) void on_dso_load_gea(void)
+{
+	gprs_cipher_register(&gea3_impl);
+	gprs_cipher_register(&gea4_impl);
+}