Move SHA256-based PRF function into a separate C file

This makes it easier to conditionally build in SHA256 functions based
on which TLS/crypto library is used.

Signed-hostap: Jouni Malinen <j@w1.fi>

hostapd/Android.mk

@@ -721,6 +721,7 @@ endif
 
 ifdef NEED_SHA256
 OBJS += src/crypto/sha256.c
+OBJS += src/crypto/sha256-prf.c
 ifdef CONFIG_INTERNAL_SHA256
 OBJS += src/crypto/sha256-internal.c
 endif

hostapd/Makefile

@@ -713,6 +713,7 @@ endif
 ifdef NEED_SHA256
 CFLAGS += -DCONFIG_SHA256
 OBJS += ../src/crypto/sha256.o
+OBJS += ../src/crypto/sha256-prf.o
 ifdef CONFIG_INTERNAL_SHA256
 OBJS += ../src/crypto/sha256-internal.o
 endif

src/crypto/sha256-prf.c

@@ -0,0 +1,64 @@
+/*
+ * SHA256-based PRF (IEEE 802.11r)
+ * Copyright (c) 2003-2007, 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"
+#include "crypto.h"
+
+
+/**
+ * sha256_prf - SHA256-based Pseudo-Random Function (IEEE 802.11r, 8.5.1.5.2)
+ * @key: Key for PRF
+ * @key_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @data: Extra data to bind into the key
+ * @data_len: Length of the data
+ * @buf: Buffer for the generated pseudo-random key
+ * @buf_len: Number of bytes of key to generate
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key.
+ */
+void sha256_prf(const u8 *key, size_t key_len, const char *label,
+		const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
+{
+	u16 counter = 1;
+	size_t pos, plen;
+	u8 hash[SHA256_MAC_LEN];
+	const u8 *addr[4];
+	size_t len[4];
+	u8 counter_le[2], length_le[2];
+
+	addr[0] = counter_le;
+	len[0] = 2;
+	addr[1] = (u8 *) label;
+	len[1] = os_strlen(label);
+	addr[2] = data;
+	len[2] = data_len;
+	addr[3] = length_le;
+	len[3] = sizeof(length_le);
+
+	WPA_PUT_LE16(length_le, buf_len * 8);
+	pos = 0;
+	while (pos < buf_len) {
+		plen = buf_len - pos;
+		WPA_PUT_LE16(counter_le, counter);
+		if (plen >= SHA256_MAC_LEN) {
+			hmac_sha256_vector(key, key_len, 4, addr, len,
+					   &buf[pos]);
+			pos += SHA256_MAC_LEN;
+		} else {
+			hmac_sha256_vector(key, key_len, 4, addr, len, hash);
+			os_memcpy(&buf[pos], hash, plen);
+			break;
+		}
+		counter++;
+	}
+}

src/crypto/sha256.c

@@ -98,54 +98,3 @@ void hmac_sha256(const u8 *key, size_t key_len, const u8 *data,
 {
 	hmac_sha256_vector(key, key_len, 1, &data, &data_len, mac);
 }
-
-
-/**
- * sha256_prf - SHA256-based Pseudo-Random Function (IEEE 802.11r, 8.5.1.5.2)
- * @key: Key for PRF
- * @key_len: Length of the key in bytes
- * @label: A unique label for each purpose of the PRF
- * @data: Extra data to bind into the key
- * @data_len: Length of the data
- * @buf: Buffer for the generated pseudo-random key
- * @buf_len: Number of bytes of key to generate
- *
- * This function is used to derive new, cryptographically separate keys from a
- * given key.
- */
-void sha256_prf(const u8 *key, size_t key_len, const char *label,
-		const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
-{
-	u16 counter = 1;
-	size_t pos, plen;
-	u8 hash[SHA256_MAC_LEN];
-	const u8 *addr[4];
-	size_t len[4];
-	u8 counter_le[2], length_le[2];
-
-	addr[0] = counter_le;
-	len[0] = 2;
-	addr[1] = (u8 *) label;
-	len[1] = os_strlen(label);
-	addr[2] = data;
-	len[2] = data_len;
-	addr[3] = length_le;
-	len[3] = sizeof(length_le);
-
-	WPA_PUT_LE16(length_le, buf_len * 8);
-	pos = 0;
-	while (pos < buf_len) {
-		plen = buf_len - pos;
-		WPA_PUT_LE16(counter_le, counter);
-		if (plen >= SHA256_MAC_LEN) {
-			hmac_sha256_vector(key, key_len, 4, addr, len,
-					   &buf[pos]);
-			pos += SHA256_MAC_LEN;
-		} else {
-			hmac_sha256_vector(key, key_len, 4, addr, len, hash);
-			os_memcpy(&buf[pos], hash, plen);
-			break;
-		}
-		counter++;
-	}
-}

wpa_supplicant/Android.mk

@@ -1123,6 +1123,7 @@ SHA256OBJS = # none by default
 ifdef NEED_SHA256
 L_CFLAGS += -DCONFIG_SHA256
 SHA256OBJS += src/crypto/sha256.c
+SHA256OBJS += src/crypto/sha256-prf.c
 ifdef CONFIG_INTERNAL_SHA256
 SHA256OBJS += src/crypto/sha256-internal.c
 endif

wpa_supplicant/Makefile

@@ -1154,6 +1154,7 @@ SHA256OBJS = # none by default
 ifdef NEED_SHA256
 CFLAGS += -DCONFIG_SHA256
 SHA256OBJS += ../src/crypto/sha256.o
+SHA256OBJS += ../src/crypto/sha256-prf.o
 ifdef CONFIG_INTERNAL_SHA256
 SHA256OBJS += ../src/crypto/sha256-internal.o
 endif