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PASN: Add function to compute LTF keyseed from KDK

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Add a function to derive the LTF keyseed from KDK. This function is
built only in case that CONFIG_PASN is enabled at build time.

Signed-off-by: Jouni Malinen <quic_jouni@quicinc.com>
This commit is contained in:
Vinay Gannevaram 2022-07-26 11:46:26 +05:30 • committed by Jouni Malinen
parent 9391f71004
commit 9330bf3189
2 changed files with 61 additions and 0 deletions
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56
src/common/wpa_common.c
View file

@ -1383,6 +1383,62 @@ u8 pasn_mic_len(int akmp, int cipher)
}
/**
* wpa_ltf_keyseed - Compute LTF keyseed from KDK
* @ptk: Buffer that holds pairwise transient key
* @akmp: Negotiated AKM
* @cipher: Negotiated pairwise cipher
* Returns: 0 on success, -1 on failure
*/
int wpa_ltf_keyseed(struct wpa_ptk *ptk, int akmp, int cipher)
{
u8 *buf;
size_t buf_len;
u8 hash[SHA384_MAC_LEN];
const u8 *kdk = ptk->kdk;
size_t kdk_len = ptk->kdk_len;
const char *label = "Secure LTF key seed";
if (!kdk || !kdk_len) {
wpa_printf(MSG_ERROR, "WPA: No KDK for LTF keyseed generation");
return -1;
}
buf = (u8 *)label;
buf_len = os_strlen(label);
if (pasn_use_sha384(akmp, cipher)) {
wpa_printf(MSG_DEBUG,
"WPA: Secure LTF keyseed using HMAC-SHA384");
if (hmac_sha384(kdk, kdk_len, buf, buf_len, hash)) {
wpa_printf(MSG_ERROR,
"WPA: HMAC-SHA384 compute failed");
return -1;
}
os_memcpy(ptk->ltf_keyseed, hash, SHA384_MAC_LEN);
ptk->ltf_keyseed_len = SHA384_MAC_LEN;
wpa_hexdump_key(MSG_DEBUG, "WPA: Secure LTF keyseed: ",
ptk->ltf_keyseed, ptk->ltf_keyseed_len);
} else {
wpa_printf(MSG_DEBUG, "WPA: LTF keyseed using HMAC-SHA256");
if (hmac_sha256(kdk, kdk_len, buf, buf_len, hash)) {
wpa_printf(MSG_ERROR,
"WPA: HMAC-SHA256 compute failed");
return -1;
}
os_memcpy(ptk->ltf_keyseed, hash, SHA256_MAC_LEN);
ptk->ltf_keyseed_len = SHA256_MAC_LEN;
wpa_hexdump_key(MSG_DEBUG, "WPA: Secure LTF keyseed: ",
ptk->ltf_keyseed, ptk->ltf_keyseed_len);
}
return 0;
}
/**
* pasn_mic - Calculate PASN MIC
* @kck: The key confirmation key for the PASN PTKSA

5
src/common/wpa_common.h
View file

@ -228,6 +228,7 @@ struct wpa_eapol_key {
#define FILS_FT_MAX_LEN 48
#define WPA_PASN_KCK_LEN 32
#define WPA_PASN_MIC_MAX_LEN 24
#define WPA_LTF_KEYSEED_MAX_LEN 48
/**
* struct wpa_ptk - WPA Pairwise Transient Key
@ -240,12 +241,14 @@ struct wpa_ptk {
u8 kck2[WPA_KCK_MAX_LEN]; /* FT reasoc Key Confirmation Key (KCK2) */
u8 kek2[WPA_KEK_MAX_LEN]; /* FT reassoc Key Encryption Key (KEK2) */
u8 kdk[WPA_KDK_MAX_LEN]; /* Key Derivation Key */
u8 ltf_keyseed[WPA_LTF_KEYSEED_MAX_LEN]; /* LTF Key seed */
size_t kck_len;
size_t kek_len;
size_t tk_len;
size_t kck2_len;
size_t kek2_len;
size_t kdk_len;
size_t ltf_keyseed_len;
int installed; /* 1 if key has already been installed to driver */
};
@ -657,6 +660,8 @@ int pasn_mic(const u8 *kck, int akmp, int cipher,
const u8 *data, size_t data_len,
const u8 *frame, size_t frame_len, u8 *mic);
int wpa_ltf_keyseed(struct wpa_ptk *ptk, int akmp, int cipher);
int pasn_auth_frame_hash(int akmp, int cipher, const u8 *data, size_t len,
u8 *hash);