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authorJouni Malinen <j@w1.fi>2015-08-27 17:42:14 (GMT)
committerJouni Malinen <j@w1.fi>2015-08-27 17:42:14 (GMT)
commitd9c807cab192474f4e0abdab1bf27256a22a204b (patch)
tree27d26e0d5913b05e08cbc756e19be93c09ced038 /src
parenta218e1ded44cc88072f4e1896fdd8bd24f1829ac (diff)
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Fix key derivation for Suite B 192-bit AKM to use SHA384
While the EAPOL-Key MIC derivation was already changed from SHA256 to SHA384 for the Suite B 192-bit AKM, KDF had not been updated similarly. Fix this by using HMAC-SHA384 instead of HMAC-SHA256 when deriving PTK from PMK when using the Suite B 192-bit AKM. Signed-off-by: Jouni Malinen <j@w1.fi>
Diffstat (limited to 'src')
-rw-r--r--src/common/wpa_common.c6
-rw-r--r--src/crypto/sha384-prf.c100
-rw-r--r--src/crypto/sha384.h5
3 files changed, 111 insertions, 0 deletions
diff --git a/src/common/wpa_common.c b/src/common/wpa_common.c
index 0492810..e9d4248 100644
--- a/src/common/wpa_common.c
+++ b/src/common/wpa_common.c
@@ -170,6 +170,12 @@ int wpa_pmk_to_ptk(const u8 *pmk, size_t pmk_len, const char *label,
ptk->tk_len = wpa_cipher_key_len(cipher);
ptk_len = ptk->kck_len + ptk->kek_len + ptk->tk_len;
+#ifdef CONFIG_SUITEB192
+ if (wpa_key_mgmt_sha384(akmp))
+ sha384_prf(pmk, pmk_len, label, data, sizeof(data),
+ tmp, ptk_len);
+ else
+#endif /* CONFIG_SUITEB192 */
#ifdef CONFIG_IEEE80211W
if (wpa_key_mgmt_sha256(akmp))
sha256_prf(pmk, pmk_len, label, data, sizeof(data),
diff --git a/src/crypto/sha384-prf.c b/src/crypto/sha384-prf.c
new file mode 100644
index 0000000..653920b
--- /dev/null
+++ b/src/crypto/sha384-prf.c
@@ -0,0 +1,100 @@
+/*
+ * SHA384-based KDF (IEEE 802.11ac)
+ * Copyright (c) 2003-2015, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "sha384.h"
+#include "crypto.h"
+
+
+/**
+ * sha384_prf - SHA384-based Key derivation function (IEEE 802.11ac, 11.6.1.7.2)
+ * @key: Key for KDF
+ * @key_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @data: Extra data to bind into the key
+ * @data_len: Length of the data
+ * @buf: Buffer for the generated pseudo-random key
+ * @buf_len: Number of bytes of key to generate
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key.
+ */
+void sha384_prf(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
+{
+ sha384_prf_bits(key, key_len, label, data, data_len, buf, buf_len * 8);
+}
+
+
+/**
+ * sha384_prf_bits - IEEE Std 802.11ac-2013, 11.6.1.7.2 Key derivation function
+ * @key: Key for KDF
+ * @key_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @data: Extra data to bind into the key
+ * @data_len: Length of the data
+ * @buf: Buffer for the generated pseudo-random key
+ * @buf_len: Number of bits of key to generate
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key. If the requested buf_len is not divisible by eight, the least
+ * significant 1-7 bits of the last octet in the output are not part of the
+ * requested output.
+ */
+void sha384_prf_bits(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf,
+ size_t buf_len_bits)
+{
+ u16 counter = 1;
+ size_t pos, plen;
+ u8 hash[SHA384_MAC_LEN];
+ const u8 *addr[4];
+ size_t len[4];
+ u8 counter_le[2], length_le[2];
+ size_t buf_len = (buf_len_bits + 7) / 8;
+
+ addr[0] = counter_le;
+ len[0] = 2;
+ addr[1] = (u8 *) label;
+ len[1] = os_strlen(label);
+ addr[2] = data;
+ len[2] = data_len;
+ addr[3] = length_le;
+ len[3] = sizeof(length_le);
+
+ WPA_PUT_LE16(length_le, buf_len_bits);
+ pos = 0;
+ while (pos < buf_len) {
+ plen = buf_len - pos;
+ WPA_PUT_LE16(counter_le, counter);
+ if (plen >= SHA384_MAC_LEN) {
+ hmac_sha384_vector(key, key_len, 4, addr, len,
+ &buf[pos]);
+ pos += SHA384_MAC_LEN;
+ } else {
+ hmac_sha384_vector(key, key_len, 4, addr, len, hash);
+ os_memcpy(&buf[pos], hash, plen);
+ pos += plen;
+ break;
+ }
+ counter++;
+ }
+
+ /*
+ * Mask out unused bits in the last octet if it does not use all the
+ * bits.
+ */
+ if (buf_len_bits % 8) {
+ u8 mask = 0xff << (8 - buf_len_bits % 8);
+ buf[pos - 1] &= mask;
+ }
+
+ os_memset(hash, 0, sizeof(hash));
+}
diff --git a/src/crypto/sha384.h b/src/crypto/sha384.h
index e6a1fe4..3deafa5 100644
--- a/src/crypto/sha384.h
+++ b/src/crypto/sha384.h
@@ -15,5 +15,10 @@ int hmac_sha384_vector(const u8 *key, size_t key_len, size_t num_elem,
const u8 *addr[], const size_t *len, u8 *mac);
int hmac_sha384(const u8 *key, size_t key_len, const u8 *data,
size_t data_len, u8 *mac);
+void sha384_prf(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf, size_t buf_len);
+void sha384_prf_bits(const u8 *key, size_t key_len, const char *label,
+ const u8 *data, size_t data_len, u8 *buf,
+ size_t buf_len_bits);
#endif /* SHA384_H */