X-Git-Url: http://www.project-moonshot.org/gitweb/?p=mech_eap.git;a=blobdiff_plain;f=libeap%2Fsrc%2Fcrypto%2Faes-ccm.c;fp=libeap%2Fsrc%2Fcrypto%2Faes-ccm.c;h=cf227785c3ca02ef41d22430f4a5a45c9694fa5a;hp=0000000000000000000000000000000000000000;hb=f3746d009c6d7f50025af1f58a85e5fee9680be6;hpb=244f18d04aaf29e68495b5ffeb40ef5cca50942f

diff --git a/libeap/src/crypto/aes-ccm.c b/libeap/src/crypto/aes-ccm.c
new file mode 100644
index 0000000..cf22778
--- /dev/null
+++ b/libeap/src/crypto/aes-ccm.c
@@ -0,0 +1,212 @@
+/*
+ * Counter with CBC-MAC (CCM) with AES
+ *
+ * Copyright (c) 2010-2012, 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 "aes.h"
+#include "aes_wrap.h"
+
+
+static void xor_aes_block(u8 *dst, const u8 *src)
+{
+	u32 *d = (u32 *) dst;
+	u32 *s = (u32 *) src;
+	*d++ ^= *s++;
+	*d++ ^= *s++;
+	*d++ ^= *s++;
+	*d++ ^= *s++;
+}
+
+
+static void aes_ccm_auth_start(void *aes, size_t M, size_t L, const u8 *nonce,
+			       const u8 *aad, size_t aad_len, size_t plain_len,
+			       u8 *x)
+{
+	u8 aad_buf[2 * AES_BLOCK_SIZE];
+	u8 b[AES_BLOCK_SIZE];
+
+	/* Authentication */
+	/* B_0: Flags | Nonce N | l(m) */
+	b[0] = aad_len ? 0x40 : 0 /* Adata */;
+	b[0] |= (((M - 2) / 2) /* M' */ << 3);
+	b[0] |= (L - 1) /* L' */;
+	os_memcpy(&b[1], nonce, 15 - L);
+	WPA_PUT_BE16(&b[AES_BLOCK_SIZE - L], plain_len);
+
+	wpa_hexdump_key(MSG_EXCESSIVE, "CCM B_0", b, AES_BLOCK_SIZE);
+	aes_encrypt(aes, b, x); /* X_1 = E(K, B_0) */
+
+	if (!aad_len)
+		return;
+
+	WPA_PUT_BE16(aad_buf, aad_len);
+	os_memcpy(aad_buf + 2, aad, aad_len);
+	os_memset(aad_buf + 2 + aad_len, 0, sizeof(aad_buf) - 2 - aad_len);
+
+	xor_aes_block(aad_buf, x);
+	aes_encrypt(aes, aad_buf, x); /* X_2 = E(K, X_1 XOR B_1) */
+
+	if (aad_len > AES_BLOCK_SIZE - 2) {
+		xor_aes_block(&aad_buf[AES_BLOCK_SIZE], x);
+		/* X_3 = E(K, X_2 XOR B_2) */
+		aes_encrypt(aes, &aad_buf[AES_BLOCK_SIZE], x);
+	}
+}
+
+
+static void aes_ccm_auth(void *aes, const u8 *data, size_t len, u8 *x)
+{
+	size_t last = len % AES_BLOCK_SIZE;
+	size_t i;
+
+	for (i = 0; i < len / AES_BLOCK_SIZE; i++) {
+		/* X_i+1 = E(K, X_i XOR B_i) */
+		xor_aes_block(x, data);
+		data += AES_BLOCK_SIZE;
+		aes_encrypt(aes, x, x);
+	}
+	if (last) {
+		/* XOR zero-padded last block */
+		for (i = 0; i < last; i++)
+			x[i] ^= *data++;
+		aes_encrypt(aes, x, x);
+	}
+}
+
+
+static void aes_ccm_encr_start(size_t L, const u8 *nonce, u8 *a)
+{
+	/* A_i = Flags | Nonce N | Counter i */
+	a[0] = L - 1; /* Flags = L' */
+	os_memcpy(&a[1], nonce, 15 - L);
+}
+
+
+static void aes_ccm_encr(void *aes, size_t L, const u8 *in, size_t len, u8 *out,
+			 u8 *a)
+{
+	size_t last = len % AES_BLOCK_SIZE;
+	size_t i;
+
+	/* crypt = msg XOR (S_1 | S_2 | ... | S_n) */
+	for (i = 1; i <= len / AES_BLOCK_SIZE; i++) {
+		WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], i);
+		/* S_i = E(K, A_i) */
+		aes_encrypt(aes, a, out);
+		xor_aes_block(out, in);
+		out += AES_BLOCK_SIZE;
+		in += AES_BLOCK_SIZE;
+	}
+	if (last) {
+		WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], i);
+		aes_encrypt(aes, a, out);
+		/* XOR zero-padded last block */
+		for (i = 0; i < last; i++)
+			*out++ ^= *in++;
+	}
+}
+
+
+static void aes_ccm_encr_auth(void *aes, size_t M, u8 *x, u8 *a, u8 *auth)
+{
+	size_t i;
+	u8 tmp[AES_BLOCK_SIZE];
+
+	wpa_hexdump_key(MSG_EXCESSIVE, "CCM T", x, M);
+	/* U = T XOR S_0; S_0 = E(K, A_0) */
+	WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], 0);
+	aes_encrypt(aes, a, tmp);
+	for (i = 0; i < M; i++)
+		auth[i] = x[i] ^ tmp[i];
+	wpa_hexdump_key(MSG_EXCESSIVE, "CCM U", auth, M);
+}
+
+
+static void aes_ccm_decr_auth(void *aes, size_t M, u8 *a, const u8 *auth, u8 *t)
+{
+	size_t i;
+	u8 tmp[AES_BLOCK_SIZE];
+
+	wpa_hexdump_key(MSG_EXCESSIVE, "CCM U", auth, M);
+	/* U = T XOR S_0; S_0 = E(K, A_0) */
+	WPA_PUT_BE16(&a[AES_BLOCK_SIZE - 2], 0);
+	aes_encrypt(aes, a, tmp);
+	for (i = 0; i < M; i++)
+		t[i] = auth[i] ^ tmp[i];
+	wpa_hexdump_key(MSG_EXCESSIVE, "CCM T", t, M);
+}
+
+
+/* AES-CCM with fixed L=2 and aad_len <= 30 assumption */
+int aes_ccm_ae(const u8 *key, size_t key_len, const u8 *nonce,
+	       size_t M, const u8 *plain, size_t plain_len,
+	       const u8 *aad, size_t aad_len, u8 *crypt, u8 *auth)
+{
+	const size_t L = 2;
+	void *aes;
+	u8 x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
+
+	if (aad_len > 30 || M > AES_BLOCK_SIZE)
+		return -1;
+
+	aes = aes_encrypt_init(key, key_len);
+	if (aes == NULL)
+		return -1;
+
+	aes_ccm_auth_start(aes, M, L, nonce, aad, aad_len, plain_len, x);
+	aes_ccm_auth(aes, plain, plain_len, x);
+
+	/* Encryption */
+	aes_ccm_encr_start(L, nonce, a);
+	aes_ccm_encr(aes, L, plain, plain_len, crypt, a);
+	aes_ccm_encr_auth(aes, M, x, a, auth);
+
+	aes_encrypt_deinit(aes);
+
+	return 0;
+}
+
+
+/* AES-CCM with fixed L=2 and aad_len <= 30 assumption */
+int aes_ccm_ad(const u8 *key, size_t key_len, const u8 *nonce,
+	       size_t M, const u8 *crypt, size_t crypt_len,
+	       const u8 *aad, size_t aad_len, const u8 *auth, u8 *plain)
+{
+	const size_t L = 2;
+	void *aes;
+	u8 x[AES_BLOCK_SIZE], a[AES_BLOCK_SIZE];
+	u8 t[AES_BLOCK_SIZE];
+
+	if (aad_len > 30 || M > AES_BLOCK_SIZE)
+		return -1;
+
+	aes = aes_encrypt_init(key, key_len);
+	if (aes == NULL)
+		return -1;
+
+	/* Decryption */
+	aes_ccm_encr_start(L, nonce, a);
+	aes_ccm_decr_auth(aes, M, a, auth, t);
+
+	/* plaintext = msg XOR (S_1 | S_2 | ... | S_n) */
+	aes_ccm_encr(aes, L, crypt, crypt_len, plain, a);
+
+	aes_ccm_auth_start(aes, M, L, nonce, aad, aad_len, crypt_len, x);
+	aes_ccm_auth(aes, plain, crypt_len, x);
+
+	aes_encrypt_deinit(aes);
+
+	if (os_memcmp_const(x, t, M) != 0) {
+		wpa_printf(MSG_EXCESSIVE, "CCM: Auth mismatch");
+		return -1;
+	}
+
+	return 0;
+}