Implement RFC 5297 AES-SIV

Add an implementation of Synthetic Initialization Vector (SIV)
Authenticated Encryption Using the Advanced Encryption Standard (AES).

This mode of AES is used to protect peering frames when using
the authenticated mesh peering exchange.

Signed-off-by: Javier Lopez <jlopex@gmail.com>
Signed-off-by: Jason Mobarak <x@jason.mobarak.name>
Signed-off-by: Bob Copeland <me@bobcopeland.com>

diff --git a/src/crypto/Makefile b/src/crypto/Makefile
index 2a921098c45d65420d533537273a455e94de7570..3e90350c103ee0db7a213eecbe7c6bbdb3d2907b 100644 (file)
--- a/src/crypto/Makefile
+++ b/src/crypto/Makefile
@@ -26,6 +26,7 @@ LIB_OBJS= \
        aes-internal-dec.o \
        aes-internal-enc.o \
        aes-omac1.o \
+       aes-siv.o \
        aes-unwrap.o \
        aes-wrap.o \
        des-internal.o \

diff --git a/src/crypto/aes-siv.c b/src/crypto/aes-siv.c
new file mode 100644 (file)
index 0000000..bd619b4
--- /dev/null
+++ b/src/crypto/aes-siv.c
@@ -0,0 +1,187 @@
+/*
+ * AES SIV (RFC 5297)
+ * Copyright (c) 2013 Cozybit, Inc.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "aes.h"
+#include "aes_wrap.h"
+
+
+static const u8 zero[AES_BLOCK_SIZE];
+
+
+static void dbl(u8 *pad)
+{
+       int i, carry;
+
+       carry = pad[0] & 0x80;
+       for (i = 0; i < AES_BLOCK_SIZE - 1; i++)
+               pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
+       pad[AES_BLOCK_SIZE - 1] <<= 1;
+       if (carry)
+               pad[AES_BLOCK_SIZE - 1] ^= 0x87;
+}
+
+
+static void xor(u8 *a, const u8 *b)
+{
+       int i;
+
+       for (i = 0; i < AES_BLOCK_SIZE; i++)
+               *a++ ^= *b++;
+}
+
+
+static void xorend(u8 *a, int alen, const u8 *b, int blen)
+{
+       int i;
+
+       if (alen < blen)
+               return;
+
+       for (i = 0; i < blen; i++)
+               a[alen - blen + i] ^= b[i];
+}
+
+
+static void pad(u8 *pad, const u8 *addr, size_t len)
+{
+       os_memset(pad, 0, AES_BLOCK_SIZE);
+       os_memcpy(pad, addr, len);
+
+       if (len < AES_BLOCK_SIZE)
+               pad[len] = 0x80;
+}
+
+
+int aes_s2v(const u8 *key, size_t num_elem, const u8 *addr[],
+           size_t *len, u8 *mac)
+{
+       u8 tmp[AES_BLOCK_SIZE], tmp2[AES_BLOCK_SIZE];
+       u8 *buf = NULL;
+       int ret;
+       size_t i;
+
+       if (!num_elem) {
+               os_memcpy(tmp, zero, sizeof(zero));
+               tmp[AES_BLOCK_SIZE - 1] = 1;
+               return omac1_aes_128(key, tmp, sizeof(tmp), mac);
+       }
+
+       ret = omac1_aes_128(key, zero, sizeof(zero), tmp);
+       if (ret)
+               return ret;
+
+       for (i = 0; i < num_elem - 1; i++) {
+               ret = omac1_aes_128(key, addr[i], len[i], tmp2);
+               if (ret)
+                       return ret;
+
+               dbl(tmp);
+               xor(tmp, tmp2);
+       }
+       if (len[i] >= AES_BLOCK_SIZE) {
+               buf = os_malloc(len[i]);
+               if (!buf)
+                       return -ENOMEM;
+
+               os_memcpy(buf, addr[i], len[i]);
+               xorend(buf, len[i], tmp, AES_BLOCK_SIZE);
+               ret = omac1_aes_128(key, buf, len[i], mac);
+               os_free(buf);
+               return ret;
+       }
+
+       dbl(tmp);
+       pad(tmp2, addr[i], len[i]);
+       xor(tmp, tmp2);
+
+       return omac1_aes_128(key, tmp, sizeof(tmp), mac);
+}
+
+
+int aes_siv_encrypt(const u8 *key, const u8 *pw,
+                   size_t pwlen, size_t num_elem,
+                   const u8 *addr[], const size_t *len, u8 *out)
+{
+       const u8 *_addr[6];
+       size_t _len[6];
+       const u8 *k1 = key, *k2 = key + 16;
+       u8 v[AES_BLOCK_SIZE];
+       size_t i;
+       u8 *iv, *crypt_pw;
+
+       if (num_elem > ARRAY_SIZE(_addr) - 1)
+               return -1;
+
+       for (i = 0; i < num_elem; i++) {
+               _addr[i] = addr[i];
+               _len[i] = len[i];
+       }
+       _addr[num_elem] = pw;
+       _len[num_elem] = pwlen;
+
+       if (aes_s2v(k1, num_elem + 1, _addr, _len, v))
+               return -1;
+
+       iv = out;
+       crypt_pw = out + AES_BLOCK_SIZE;
+
+       os_memcpy(iv, v, AES_BLOCK_SIZE);
+       os_memcpy(crypt_pw, pw, pwlen);
+
+       /* zero out 63rd and 31st bits of ctr (from right) */
+       v[8] &= 0x7f;
+       v[12] &= 0x7f;
+       return aes_128_ctr_encrypt(k2, v, crypt_pw, pwlen);
+}
+
+
+int aes_siv_decrypt(const u8 *key, const u8 *iv_crypt, size_t iv_c_len,
+                   size_t num_elem, const u8 *addr[], const size_t *len,
+                   u8 *out)
+{
+       const u8 *_addr[6];
+       size_t _len[6];
+       const u8 *k1 = key, *k2 = key + 16;
+       size_t crypt_len;
+       size_t i;
+       int ret;
+       u8 iv[AES_BLOCK_SIZE];
+       u8 check[AES_BLOCK_SIZE];
+
+       if (iv_c_len < AES_BLOCK_SIZE || num_elem > ARRAY_SIZE(_addr) - 1)
+               return -1;
+       crypt_len = iv_c_len - AES_BLOCK_SIZE;
+
+       for (i = 0; i < num_elem; i++) {
+               _addr[i] = addr[i];
+               _len[i] = len[i];
+       }
+       _addr[num_elem] = out;
+       _len[num_elem] = crypt_len;
+
+       os_memcpy(iv, iv_crypt, AES_BLOCK_SIZE);
+       os_memcpy(out, iv_crypt + AES_BLOCK_SIZE, crypt_len);
+
+       iv[8] &= 0x7f;
+       iv[12] &= 0x7f;
+
+       ret = aes_128_ctr_encrypt(k2, iv, out, crypt_len);
+       if (ret)
+               return ret;
+
+       ret = aes_s2v(k1, num_elem + 1, _addr, _len, check);
+       if (ret)
+               return ret;
+       if (os_memcmp(check, iv_crypt, AES_BLOCK_SIZE) == 0)
+               return 0;
+
+       return -1;
+}

diff --git a/src/crypto/aes_siv.h b/src/crypto/aes_siv.h
new file mode 100644 (file)
index 0000000..463cf65
--- /dev/null
+++ b/src/crypto/aes_siv.h
@@ -0,0 +1,19 @@
+/*
+ * AES SIV (RFC 5297)
+ * Copyright (c) 2013 Cozybit, Inc.
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#ifndef AES_SIV_H
+#define AES_SIV_H
+
+int aes_siv_encrypt(const u8 *key, const u8 *pw,
+                   size_t pwlen, size_t num_elem,
+                   const u8 *addr[], const size_t *len, u8 *out);
+int aes_siv_decrypt(const u8 *key, const u8 *iv_crypt, size_t iv_c_len,
+                   size_t num_elem, const u8 *addr[], const size_t *len,
+                   u8 *out);
+
+#endif /* AES_SIV_H */

diff --git a/wpa_supplicant/Android.mk b/wpa_supplicant/Android.mk
index 3e028f938ca4c70802c2fb716c89ca1041c87dff..d78ba78ebee4e7a0f6b3e1a31c78bdfb34a281b6 100644 (file)
--- a/wpa_supplicant/Android.mk
+++ b/wpa_supplicant/Android.mk
@@ -1143,6 +1143,9 @@ ifdef CONFIG_INTERNAL_AES
 AESOBJS += src/crypto/aes-internal-enc.c
 endif
 endif
+ifdef NEED_AES_SIV
+AESOBJS += src/crypto/aes-siv.c
+endif
 ifdef NEED_AES
 OBJS += $(AESOBJS)
 endif

diff --git a/wpa_supplicant/Makefile b/wpa_supplicant/Makefile
index 7851fa3480478dfd04aef129180c224ce26f3bee..7a682469746d5394583aba0c599dadb64da1fbe7 100644 (file)
--- a/wpa_supplicant/Makefile
+++ b/wpa_supplicant/Makefile
@@ -1145,6 +1145,9 @@ else
 AESOBJS += ../src/crypto/aes-omac1.o
 endif
 endif
+ifdef NEED_AES_SIV
+AESOBJS += ../src/crypto/aes-siv.o
+endif
 ifdef NEED_AES_WRAP
 NEED_AES_ENC=y
 AESOBJS += ../src/crypto/aes-wrap.o