Merged the hostap_2.6 updates, and the Leap of Faith work, from the hostap_update...

[mech_eap.git] / libeap / src / crypto / sha256-tlsprf.c

diff --git a/libeap/src/crypto/sha256-tlsprf.c b/libeap/src/crypto/sha256-tlsprf.c
new file mode 100644 (file)
index 0000000..0528dad
--- /dev/null
+++ b/libeap/src/crypto/sha256-tlsprf.c
@@ -0,0 +1,66 @@
+/*
+ * TLS PRF P_SHA256
+ * Copyright (c) 2011, 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 "sha256.h"
+
+
+/**
+ * tls_prf_sha256 - Pseudo-Random Function for TLS v1.2 (P_SHA256, RFC 5246)
+ * @secret: Key for PRF
+ * @secret_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @seed: Seed value to bind into the key
+ * @seed_len: Length of the seed
+ * @out: Buffer for the generated pseudo-random key
+ * @outlen: Number of bytes of key to generate
+ * Returns: 0 on success, -1 on failure.
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key in TLS. This PRF is defined in RFC 2246, Chapter 5.
+ */
+void tls_prf_sha256(const u8 *secret, size_t secret_len, const char *label,
+                   const u8 *seed, size_t seed_len, u8 *out, size_t outlen)
+{
+       size_t clen;
+       u8 A[SHA256_MAC_LEN];
+       u8 P[SHA256_MAC_LEN];
+       size_t pos;
+       const unsigned char *addr[3];
+       size_t len[3];
+
+       addr[0] = A;
+       len[0] = SHA256_MAC_LEN;
+       addr[1] = (unsigned char *) label;
+       len[1] = os_strlen(label);
+       addr[2] = seed;
+       len[2] = seed_len;
+
+       /*
+        * RFC 5246, Chapter 5
+        * A(0) = seed, A(i) = HMAC(secret, A(i-1))
+        * P_hash = HMAC(secret, A(1) + seed) + HMAC(secret, A(2) + seed) + ..
+        * PRF(secret, label, seed) = P_SHA256(secret, label + seed)
+        */
+
+       hmac_sha256_vector(secret, secret_len, 2, &addr[1], &len[1], A);
+
+       pos = 0;
+       while (pos < outlen) {
+               hmac_sha256_vector(secret, secret_len, 3, addr, len, P);
+               hmac_sha256(secret, secret_len, A, SHA256_MAC_LEN, A);
+
+               clen = outlen - pos;
+               if (clen > SHA256_MAC_LEN)
+                       clen = SHA256_MAC_LEN;
+               os_memcpy(out + pos, P, clen);
+               pos += clen;
+       }
+}