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crypto: allow hkdf_expand/extract to use different SHA's

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Rather than hard coding to SHA256, we can pass in l_checksum_type
and use that SHA. This will allow for OWE/SAE/PWD to support more
curves that use different SHA algorithms for hashing.
This commit is contained in:
James Prestwood 2019-01-17 12:25:36 -08:00 committed by Denis Kenzior
parent 90c39afd61
commit 7bfaf182e6
5 changed files with 42 additions and 30 deletions
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34
src/crypto.c
View File

@ -418,19 +418,24 @@ bool kdf_sha256(const void *key, size_t key_len,
*
* Null key equates to a zero key (makes calls in EAP-PWD more convenient)
*/
bool hkdf_extract_sha256(const uint8_t *key, size_t key_len, uint8_t num_args,
bool hkdf_extract(enum l_checksum_type type, const uint8_t *key,
size_t key_len, uint8_t num_args,
uint8_t *out, ...)
{
struct l_checksum *hmac;
struct iovec iov[num_args];
const uint8_t zero_key[32] = { 0 };
const uint8_t zero_key[64] = { 0 };
size_t dlen = l_checksum_digest_length(type);
const uint8_t *k = key ? key : zero_key;
size_t k_len = key ? key_len : 32;
size_t k_len = key ? key_len : dlen;
va_list va;
int i;
int ret;
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, k, k_len);
if (dlen <= 0)
return false;
hmac = l_checksum_new_hmac(type, k, k_len);
if (!hmac)
return false;
@ -446,27 +451,32 @@ bool hkdf_extract_sha256(const uint8_t *key, size_t key_len, uint8_t num_args,
return false;
}
ret = l_checksum_get_digest(hmac, out, 32);
ret = l_checksum_get_digest(hmac, out, dlen);
l_checksum_free(hmac);
va_end(va);
return (ret == 32);
return (ret == (int) dlen);
}
bool hkdf_expand_sha256(const uint8_t *key, size_t key_len, const char *info,
size_t info_len, void *out, size_t out_len)
bool hkdf_expand(enum l_checksum_type type, const uint8_t *key, size_t key_len,
const char *info, size_t info_len, void *out,
size_t out_len)
{
uint8_t t[32];
uint8_t t[64];
size_t t_len = 0;
struct iovec iov[3];
struct l_checksum *hmac;
uint8_t count = 1;
uint8_t *out_ptr = out;
size_t dlen = l_checksum_digest_length(type);
if (dlen <= 0)
return false;
while (out_len > 0) {
ssize_t ret;
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, key, key_len);
hmac = l_checksum_new_hmac(type, key, key_len);
iov[0].iov_base = t;
iov[0].iov_len = t_len;
@ -481,7 +491,7 @@ bool hkdf_expand_sha256(const uint8_t *key, size_t key_len, const char *info,
}
ret = l_checksum_get_digest(hmac, t,
(out_len > 32) ? 32 : out_len);
(out_len > dlen) ? dlen : out_len);
if (ret < 0) {
l_checksum_free(hmac);
return false;
@ -495,7 +505,7 @@ bool hkdf_expand_sha256(const uint8_t *key, size_t key_len, const char *info,
* RFC specifies that T(0) = empty string, so after the first
* iteration we update the length for T(1)...T(N)
*/
t_len = 32;
t_len = dlen;
count++;
l_checksum_free(hmac);

9
src/crypto.h
View File

@ -89,11 +89,12 @@ bool kdf_sha256(const void *key, size_t key_len,
bool prf_sha1(const void *key, size_t key_len,
const void *prefix, size_t prefix_len,
const void *data, size_t data_len, void *output, size_t size);
bool hkdf_extract_sha256(const uint8_t *key, size_t key_len, uint8_t num_args,
uint8_t *out, ...);
bool hkdf_extract(enum l_checksum_type type, const uint8_t *key, size_t key_len,
uint8_t num_args, uint8_t *out, ...);
bool hkdf_expand_sha256(const uint8_t *key, size_t key_len, const char *info,
size_t info_len, void *out, size_t out_len);
bool hkdf_expand(enum l_checksum_type type, const uint8_t *key, size_t key_len,
const char *info, size_t info_len, void *out,
size_t out_len);
bool crypto_derive_pairwise_ptk(const uint8_t *pmk, size_t pmk_len,
const uint8_t *addr1, const uint8_t *addr2,

21
src/eap-pwd.c
View File

@ -293,7 +293,7 @@ static void eap_pwd_handle_id(struct eap_state *eap,
while (counter < 20) {
/* pwd-seed = H(token|peer-ID|server-ID|password|counter) */
hkdf_extract_sha256(NULL, 0, 5, pwd_seed, &token, 4,
hkdf_extract(L_CHECKSUM_SHA256, NULL, 0, 5, pwd_seed, &token, 4,
pwd->identity, strlen(pwd->identity), pkt + 9,
len - 9, pwd->password, strlen(pwd->password),
&counter, 1);
@ -488,13 +488,14 @@ static void eap_pwd_handle_confirm(struct eap_state *eap,
* compute Confirm_P = H(kp | Element_P | Scalar_P |
* Element_S | Scalar_S | Ciphersuite)
*/
hkdf_extract_sha256(NULL, 0, 6, confirm_p, kpx, clen, element_p, plen,
scalar_p, clen, element_s, plen, scalar_s,
clen, &pwd->ciphersuite, 4);
hkdf_extract(L_CHECKSUM_SHA256, NULL, 0, 6, confirm_p, kpx, clen,
element_p, plen, scalar_p, clen, element_s,
plen, scalar_s, clen, &pwd->ciphersuite, 4);
hkdf_extract_sha256(NULL, 0, 6, expected_confirm_s, kpx, clen,
element_s, plen, scalar_s, clen, element_p,
plen, scalar_p, clen, &pwd->ciphersuite, 4);
hkdf_extract(L_CHECKSUM_SHA256, NULL, 0, 6, expected_confirm_s, kpx,
clen, element_s, plen, scalar_s, clen,
element_p, plen, scalar_p, clen,
&pwd->ciphersuite, 4);
if (memcmp(confirm_s, expected_confirm_s, 32)) {
l_error("Confirm_S did not verify");
@ -507,7 +508,7 @@ static void eap_pwd_handle_confirm(struct eap_state *eap,
pos += 32;
/* derive MK = H(kp | Confirm_P | Confirm_S ) */
hkdf_extract_sha256(NULL, 0, 3, mk, kpx, clen, confirm_p,
hkdf_extract(L_CHECKSUM_SHA256, NULL, 0, 3, mk, kpx, clen, confirm_p,
32, confirm_s, 32);
eap_pwd_send_response(eap, resp, pos - resp);
@ -515,8 +516,8 @@ static void eap_pwd_handle_confirm(struct eap_state *eap,
eap_method_success(eap);
session_id[0] = 52;
hkdf_extract_sha256(NULL, 0, 3, session_id + 1, &pwd->ciphersuite, 4,
scalar_p, clen, scalar_s, clen);
hkdf_extract(L_CHECKSUM_SHA256, NULL, 0, 3, session_id + 1,
&pwd->ciphersuite, 4, scalar_p, clen, scalar_s, clen);
kdf(mk, 32, (const char *) session_id, 33, msk_emsk, 128);
eap_set_key_material(eap, msk_emsk, 64, msk_emsk + 64, 64, NULL, 0);

4
src/owe.c
View File

@ -157,11 +157,11 @@ static bool owe_compute_keys(struct owe_sm *owe, const void *public_key,
l_put_le16(OWE_DEFAULT_GROUP, key + 64);
/* prk = HKDF-extract(C | A | group, z) */
if (!hkdf_extract_sha256(key, 66, 1, prk, ss_buf, 32))
if (!hkdf_extract(L_CHECKSUM_SHA256, key, 66, 1, prk, ss_buf, 32))
goto failed;
/* PMK = HKDF-expand(prk, "OWE Key Generation", n) */
if (!hkdf_expand_sha256(prk, 32, "OWE Key Generation",
if (!hkdf_expand(L_CHECKSUM_SHA256, prk, 32, "OWE Key Generation",
strlen("OWE Key Generation"), pmk, 32))
goto failed;

2
src/sae.c
View File

@ -83,7 +83,7 @@ static bool sae_pwd_seed(const uint8_t *addr1, const uint8_t *addr2,
memcpy(key + 6, addr1, 6);
}
return hkdf_extract_sha256(key, 12, 2, out, base, base_len,
return hkdf_extract(L_CHECKSUM_SHA256, key, 12, 2, out, base, base_len,
&counter, 1);
}