diff options
Diffstat (limited to 'src/crypto/sha256-kdf.c')
| -rw-r--r-- | src/crypto/sha256-kdf.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/src/crypto/sha256-kdf.c b/src/crypto/sha256-kdf.c index e7509ce41aba4..af7d954d8a440 100644 --- a/src/crypto/sha256-kdf.c +++ b/src/crypto/sha256-kdf.c @@ -1,6 +1,6 @@ /* - * HMAC-SHA256 KDF (RFC 5295) - * Copyright (c) 2014, Jouni Malinen <j@w1.fi> + * HMAC-SHA256 KDF (RFC 5295) and HKDF-Expand(SHA256) (RFC 5869) + * Copyright (c) 2014-2017, Jouni Malinen <j@w1.fi> * * This software may be distributed under the terms of the BSD license. * See README for more details. @@ -16,7 +16,8 @@ * hmac_sha256_kdf - HMAC-SHA256 based KDF (RFC 5295) * @secret: Key for KDF * @secret_len: Length of the key in bytes - * @label: A unique label for each purpose of the KDF + * @label: A unique label for each purpose of the KDF or %NULL to select + * RFC 5869 HKDF-Expand() with arbitrary seed (= info) * @seed: Seed value to bind into the key * @seed_len: Length of the seed * @out: Buffer for the generated pseudo-random key @@ -24,7 +25,9 @@ * Returns: 0 on success, -1 on failure. * * This function is used to derive new, cryptographically separate keys from a - * given key in ERP. This KDF is defined in RFC 5295, Chapter 3.1.2. + * given key in ERP. This KDF is defined in RFC 5295, Chapter 3.1.2. When used + * with label = NULL and seed = info, this matches HKDF-Expand() defined in + * RFC 5869, Chapter 2.3. */ int hmac_sha256_kdf(const u8 *secret, size_t secret_len, const char *label, const u8 *seed, size_t seed_len, @@ -38,8 +41,13 @@ int hmac_sha256_kdf(const u8 *secret, size_t secret_len, addr[0] = T; len[0] = SHA256_MAC_LEN; - addr[1] = (const unsigned char *) label; - len[1] = os_strlen(label) + 1; + if (label) { + addr[1] = (const unsigned char *) label; + len[1] = os_strlen(label) + 1; + } else { + addr[1] = (const u8 *) ""; + len[1] = 0; + } addr[2] = seed; len[2] = seed_len; addr[3] = &iter; |