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crypto: Generalize kdf_sha{256|384} as crypto_kdf

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This also allows us to easily implement KDF with SHA512
This commit is contained in:
Denis Kenzior 2021-07-11 22:09:33 -05:00
parent e82f0d3459
commit d12ac0fa71
2 changed files with 27 additions and 51 deletions
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75
src/crypto.c
View File

@ -749,13 +749,15 @@ bool prf_plus_sha1(const void *key, size_t key_len,
}
/* Defined in 802.11-2012, Section 11.6.1.7.2 Key derivation function (KDF) */
bool kdf_sha256(const void *key, size_t key_len,
bool crypto_kdf(enum l_checksum_type type, 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)
{
struct l_checksum *hmac;
unsigned int i, offset = 0;
unsigned int counter;
unsigned int chunk_size;
unsigned int n_iterations;
uint8_t counter_le[2];
uint8_t length_le[2];
struct iovec iov[4] = {
@ -765,19 +767,21 @@ bool kdf_sha256(const void *key, size_t key_len,
[3] = { .iov_base = length_le, .iov_len = 2 },
};
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA256, key, key_len);
hmac = l_checksum_new_hmac(type, key, key_len);
if (!hmac)
return false;
chunk_size = l_checksum_digest_length(type);
n_iterations = (size + chunk_size - 1) / chunk_size;
/* Length is denominated in bits, not bytes */
l_put_le16(size * 8, length_le);
/* KDF processes in 256-bit chunks (32 bytes) */
for (i = 0, counter = 1; i < (size + 31) / 32; i++, counter++) {
for (i = 0, counter = 1; i < n_iterations; i++, counter++) {
size_t len;
if (size - offset > 32)
len = 32;
if (size - offset > chunk_size)
len = chunk_size;
else
len = size - offset;
@ -794,49 +798,20 @@ bool kdf_sha256(const void *key, size_t key_len,
return true;
}
bool kdf_sha256(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)
{
return crypto_kdf(L_CHECKSUM_SHA256, key, key_len, prefix, prefix_len,
data, data_len, output, size);
}
bool kdf_sha384(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)
{
struct l_checksum *hmac;
unsigned int i, offset = 0;
unsigned int counter;
uint8_t counter_le[2];
uint8_t length_le[2];
struct iovec iov[4] = {
[0] = { .iov_base = counter_le, .iov_len = 2 },
[1] = { .iov_base = (void *) prefix, .iov_len = prefix_len },
[2] = { .iov_base = (void *) data, .iov_len = data_len },
[3] = { .iov_base = length_le, .iov_len = 2 },
};
hmac = l_checksum_new_hmac(L_CHECKSUM_SHA384, key, key_len);
if (!hmac)
return false;
/* Length is denominated in bits, not bytes */
l_put_le16(size * 8, length_le);
/* KDF processes in 384-bit chunks (48 bytes) */
for (i = 0, counter = 1; i < (size + 47) / 48; i++, counter++) {
size_t len;
if (size - offset > 48)
len = 48;
else
len = size - offset;
l_put_le16(counter, counter_le);
l_checksum_updatev(hmac, iov, 4);
l_checksum_get_digest(hmac, output + offset, len);
offset += len;
}
l_checksum_free(hmac);
return true;
return crypto_kdf(L_CHECKSUM_SHA384, key, key_len, prefix, prefix_len,
data, data_len, output, size);
}
/*
@ -939,14 +914,12 @@ static bool crypto_derive_ptk(const uint8_t *pmk, size_t pmk_len,
}
pos += 64;
if (type == L_CHECKSUM_SHA384)
return kdf_sha384(pmk, pmk_len, label, strlen(label),
data, sizeof(data), out_ptk, ptk_len);
else if (type == L_CHECKSUM_SHA256)
return kdf_sha256(pmk, pmk_len, label, strlen(label),
if (type == L_CHECKSUM_SHA1)
return prf_sha1(pmk, pmk_len, label, strlen(label),
data, sizeof(data), out_ptk, ptk_len);
else
return prf_sha1(pmk, pmk_len, label, strlen(label),
return crypto_kdf(type, pmk, pmk_len, label, strlen(label),
data, sizeof(data), out_ptk, ptk_len);
}

3
src/crypto.h
View File

@ -99,6 +99,9 @@ int crypto_psk_from_passphrase(const char *passphrase,
const unsigned char *ssid, size_t ssid_len,
unsigned char *out_psk);
bool crypto_kdf(enum l_checksum_type type, 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 kdf_sha256(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);