wlantest: Move GCM-AE and GCM-AD into separate functions

This splits the more generic GCM operations from GCMP specific
implementation.

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

wlantest/gcmp.c

@@ -152,6 +152,179 @@ static void aes_gctr(void *aes, const u8 *icb, const u8 *x, size_t xlen, u8 *y)
 }
 
 
+/**
+ * aes_gcm_ae - GCM-AE_K(IV, P, A) with len(IV) = 96
+ */
+static int aes_gcm_ae(const u8 *key, const u8 *iv,
+		      const u8 *plain, size_t plain_len,
+		      const u8 *aad, size_t aad_len,
+		      u8 *crypt, u8 *tag)
+{
+	u8 *auth, *apos;
+	u8 H[AES_BLOCK_SIZE];
+	u8 J0[AES_BLOCK_SIZE];
+	u8 S[16];
+	void *aes;
+	size_t padlen;
+	size_t iv_len = 12;
+
+	aes = aes_encrypt_init(key, 16);
+	if (aes == NULL)
+		return -1;
+
+	/* 1. Generate hash subkey H = AES_K(0^128) */
+	os_memset(H, 0, sizeof(H));
+	aes_encrypt(aes, H, H);
+	wpa_hexdump_key(MSG_EXCESSIVE, "Hash subkey H for GHASH", H, sizeof(H));
+
+	/* 2. Prepare block J_0 = IV || 0^31 || 1 [len(IV) = 96] */
+	os_memcpy(J0, iv, iv_len);
+	os_memset(J0 + iv_len, 0, AES_BLOCK_SIZE - iv_len);
+	J0[AES_BLOCK_SIZE - 1] = 0x01;
+
+	/* 3. C = GCTR_K(inc_32(J_0), P) */
+	inc32(J0);
+	aes_gctr(aes, J0, plain, plain_len, crypt);
+
+	/*
+	 * 4. u = 128 * ceil[len(C)/128] - len(C)
+	 *    v = 128 * ceil[len(A)/128] - len(A)
+	 * 5. S = GHASH_H(A || 0^v || C || 0^u || [len(A)]64 || [len(C)]64)
+	 * (i.e., zero padded to block size A || C and lengths of each in bits)
+	 */
+	auth = os_malloc(32 + 16 + plain_len + 8 + 8);
+	if (auth == NULL) {
+		aes_encrypt_deinit(aes);
+		return -1;
+	}
+
+	apos = auth;
+
+	/* Zero-padded AAD */
+	os_memcpy(apos, aad, aad_len);
+	apos += aad_len;
+	padlen = (16 - aad_len % 16) % 16;
+	os_memset(apos, 0, padlen);
+	apos += padlen;
+
+	/* Zero-padded C */
+	os_memcpy(apos, crypt, plain_len);
+	apos += plain_len;
+	padlen = (16 - plain_len % 16) % 16;
+	os_memset(apos, 0, padlen);
+	apos += padlen;
+
+	/* Length of AAD and C in bits */
+	WPA_PUT_BE64(apos, aad_len * 8);
+	apos += 8;
+	WPA_PUT_BE64(apos, plain_len * 8);
+	apos += 8;
+
+	wpa_hexdump_key(MSG_EXCESSIVE, "GHASH_H input", auth, apos - auth);
+	ghash(H, auth, apos - auth, S);
+	wpa_hexdump_key(MSG_EXCESSIVE, "S = GHASH_H(...)", S, 16);
+	os_free(auth);
+
+	/* 6. T = MSB_t(GCTR_K(J_0, S)) */
+	J0[AES_BLOCK_SIZE - 1] = 0x01;
+	aes_gctr(aes, J0, S, sizeof(S), tag);
+
+	/* 7. Return (C, T) */
+
+	aes_encrypt_deinit(aes);
+
+	return 0;
+}
+
+
+/**
+ * aes_gcm_ad - GCM-AD_K(IV, C, A, T) with len(IV) = 96
+ */
+static int aes_gcm_ad(const u8 *key, const u8 *iv,
+		      const u8 *crypt, size_t crypt_len,
+		      const u8 *aad, size_t aad_len, const u8 *tag,
+		      u8 *plain)
+{
+	u8 *auth, *apos;
+	u8 H[AES_BLOCK_SIZE];
+	u8 J0[AES_BLOCK_SIZE];
+	u8 S[16], T[16];
+	void *aes;
+	size_t padlen;
+	size_t iv_len = 12;
+
+	aes = aes_encrypt_init(key, 16);
+	if (aes == NULL)
+		return -1;
+
+	/* 2. Generate hash subkey H = AES_K(0^128) */
+	os_memset(H, 0, sizeof(H));
+	aes_encrypt(aes, H, H);
+	wpa_hexdump(MSG_EXCESSIVE, "Hash subkey H for GHASH", H, sizeof(H));
+
+	/* 3. Prepare block J_0 = IV || 0^31 || 1 [len(IV) = 96] */
+	os_memcpy(J0, iv, iv_len);
+	os_memset(J0 + iv_len, 0, AES_BLOCK_SIZE - iv_len);
+	J0[AES_BLOCK_SIZE - 1] = 0x01;
+
+	/* 4. C = GCTR_K(inc_32(J_0), C) */
+	inc32(J0);
+	aes_gctr(aes, J0, crypt, crypt_len, plain);
+
+	/*
+	 * 5. u = 128 * ceil[len(C)/128] - len(C)
+	 *    v = 128 * ceil[len(A)/128] - len(A)
+	 * 6. S = GHASH_H(A || 0^v || C || 0^u || [len(A)]64 || [len(C)]64)
+	 * (i.e., zero padded to block size A || C and lengths of each in bits)
+	 */
+	auth = os_malloc(32 + 16 + crypt_len + 8 + 8);
+	if (auth == NULL) {
+		aes_encrypt_deinit(aes);
+		return -1;
+	}
+
+	apos = auth;
+
+	/* Zero-padded AAD */
+	os_memcpy(apos, aad, aad_len);
+	apos += aad_len;
+	padlen = (16 - aad_len % 16) % 16;
+	os_memset(apos, 0, padlen);
+	apos += padlen;
+
+	/* Zero-padded C */
+	os_memcpy(apos, crypt, crypt_len);
+	apos += crypt_len;
+	padlen = (16 - crypt_len % 16) % 16;
+	os_memset(apos, 0, padlen);
+	apos += padlen;
+
+	/* Length of AAD and C in bits */
+	WPA_PUT_BE64(apos, aad_len * 8);
+	apos += 8;
+	WPA_PUT_BE64(apos, crypt_len * 8);
+	apos += 8;
+
+	wpa_hexdump(MSG_EXCESSIVE, "GHASH_H input", auth, apos - auth);
+	ghash(H, auth, apos - auth, S);
+	wpa_hexdump(MSG_EXCESSIVE, "S = GHASH_H(...)", S, 16);
+	os_free(auth);
+
+	/* 7. T' = MSB_t(GCTR_K(J_0, S)) */
+	J0[AES_BLOCK_SIZE - 1] = 0x01;
+	aes_gctr(aes, J0, S, sizeof(S), T);
+
+	aes_encrypt_deinit(aes);
+
+	if (os_memcmp(tag, T, 16) != 0) {
+		wpa_printf(MSG_EXCESSIVE, "GCM: Tag mismatch");
+		return -1;
+	}
+
+	return 0;
+}
+
+
 static void gcmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
 			   u8 *aad, size_t *aad_len, u8 *nonce)
 {
@@ -213,12 +386,8 @@ static void gcmp_aad_nonce(const struct ieee80211_hdr *hdr, const u8 *data,
 u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 		  const u8 *data, size_t data_len, size_t *decrypted_len)
 {
-	u8 aad[2 + 30], nonce[12], *plain, *auth, *apos;
-	u8 H[AES_BLOCK_SIZE];
-	u8 J0[AES_BLOCK_SIZE];
-	u8 S[16], T[16];
-	size_t aad_len, padlen, mlen;
-	void *aes;
+	u8 aad[2 + 30], nonce[12], *plain;
+	size_t aad_len, mlen;
 	const u8 *m;
 
 	if (data_len < 8 + 16)
@@ -228,12 +397,6 @@ u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 	if (plain == NULL)
 		return NULL;
 
-	aes = aes_encrypt_init(tk, 16);
-	if (aes == NULL) {
-		os_free(plain);
-		return NULL;
-	}
-
 	m = data + 8;
 	mlen = data_len - 8 - 16;
 
@@ -243,86 +406,20 @@ u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", &aad[2], aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 
-	/* GCM-AD_K(IV, C, A, T)
-	 *
-	 * IV = GCMP nonce
-	 * A = AAD
-	 * C | T = received frame
-	 */
-
-	/* 2. Generate hash subkey H = AES_K(0^128) */
-	os_memset(H, 0, sizeof(H));
-	aes_encrypt(aes, H, H);
-	wpa_hexdump(MSG_EXCESSIVE, "Hash subkey H for GHASH", H, sizeof(H));
-
-	/* 3. Prepare block J_0 = IV || 0^31 || 1 [len(IV) = 96] */
-	os_memcpy(J0, nonce, sizeof(nonce));
-	os_memset(J0 + sizeof(nonce), 0, AES_BLOCK_SIZE - sizeof(nonce));
-	J0[AES_BLOCK_SIZE - 1] = 0x01;
-
-	/* 4. C = GCTR_K(inc_32(J_0), C) */
-	inc32(J0);
-	aes_gctr(aes, J0, m, mlen, plain);
-
-	/*
-	 * 5. u = 128 * ceil[len(C)/128] - len(C)
-	 *    v = 128 * ceil[len(A)/128] - len(A)
-	 * 6. S = GHASH_H(A || 0^v || C || 0^u || [len(A)]64 || [len(C)]64)
-	 * (i.e., zero padded to block size A || C and lengths of each in bits)
-	 */
-	auth = os_malloc(32 + 16 + data_len - 16 + 8 + 8);
-	if (auth == NULL) {
-		os_free(plain);
-		return NULL;
-	}
-
-	apos = auth;
-
-	/* Zero-padded AAD */
-	os_memcpy(apos, &aad[2], aad_len);
-	apos += aad_len;
-	padlen = (16 - aad_len % 16) % 16;
-	os_memset(apos, 0, padlen);
-	apos += padlen;
-
-	/* Zero-padded C */
-	os_memcpy(apos, m, mlen);
-	apos += mlen;
-	padlen = (16 - mlen % 16) % 16;
-	os_memset(apos, 0, padlen);
-	apos += padlen;
-
-	/* Length of AAD and C in bits */
-	WPA_PUT_BE64(apos, aad_len * 8);
-	apos += 8;
-	WPA_PUT_BE64(apos, mlen * 8);
-	apos += 8;
-
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP GHASH_H input", auth, apos - auth);
-	ghash(H, auth, apos - auth, S);
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP S = GHASH_H(...)", S, 16);
-	os_free(auth);
-
-	/* 7. T' = MSB_t(GCTR_K(J_0, S)) */
-	J0[AES_BLOCK_SIZE - 1] = 0x01;
-	aes_gctr(aes, J0, S, sizeof(S), T);
-
-	aes_encrypt_deinit(aes);
-
-	if (os_memcmp(data + data_len - 16, T, 16) != 0) {
+	if (aes_gcm_ad(tk, nonce, m, mlen, &aad[2], aad_len, m + mlen, plain) <
+	    0) {
 		u16 seq_ctrl = le_to_host16(hdr->seq_ctrl);
-		wpa_printf(MSG_INFO, "Invalid GCMP MIC in frame: A1=" MACSTR
+		wpa_printf(MSG_INFO, "Invalid GCMP frame: A1=" MACSTR
 			   " A2=" MACSTR " A3=" MACSTR " seq=%u frag=%u",
 			   MAC2STR(hdr->addr1), MAC2STR(hdr->addr2),
 			   MAC2STR(hdr->addr3),
 			   WLAN_GET_SEQ_SEQ(seq_ctrl),
 			   WLAN_GET_SEQ_FRAG(seq_ctrl));
-		wpa_hexdump(MSG_DEBUG, "GCMP decrypted", plain, data_len - 16);
 		os_free(plain);
 		return NULL;
 	}
 
-	*decrypted_len = data_len - 8 - 16;
+	*decrypted_len = mlen;
 	return plain;
 }
 
@@ -330,13 +427,9 @@ u8 * gcmp_decrypt(const u8 *tk, const struct ieee80211_hdr *hdr,
 u8 * gcmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
 		  u8 *pn, int keyid, size_t *encrypted_len)
 {
-	u8 aad[2 + 30], nonce[12], *crypt, *pos, *auth, *apos;
-	u8 H[AES_BLOCK_SIZE];
-	u8 J0[AES_BLOCK_SIZE];
-	u8 S[16];
-	size_t aad_len, plen, padlen;
+	u8 aad[2 + 30], nonce[12], *crypt, *pos;
+	size_t aad_len, plen;
 	struct ieee80211_hdr *hdr;
-	void *aes;
 
 	if (len < hdrlen || hdrlen < 24)
 		return NULL;
@@ -359,88 +452,20 @@ u8 * gcmp_encrypt(const u8 *tk, u8 *frame, size_t len, size_t hdrlen, u8 *qos,
 	*pos++ = pn[1]; /* PN4 */
 	*pos++ = pn[0]; /* PN5 */
 
-	aes = aes_encrypt_init(tk, 16);
-	if (aes == NULL) {
-		os_free(crypt);
-		return NULL;
-	}
-
 	os_memset(aad, 0, sizeof(aad));
 	gcmp_aad_nonce(hdr, crypt + hdrlen, &aad[2], &aad_len, nonce);
 	WPA_PUT_BE16(aad, aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP AAD", &aad[2], aad_len);
 	wpa_hexdump(MSG_EXCESSIVE, "GCMP nonce", nonce, sizeof(nonce));
 
-	/* GCM-AE_K(IV, P, A)
-	 *
-	 * IV = GCMP nonce
-	 * A = AAD
-	 */
-
-	/* 1. Generate hash subkey H = AES_K(0^128) */
-	os_memset(H, 0, sizeof(H));
-	aes_encrypt(aes, H, H);
-	wpa_hexdump(MSG_EXCESSIVE, "Hash subkey H for GHASH", H, sizeof(H));
-
-	/* 2. Prepare block J_0 = IV || 0^31 || 1 [len(IV) = 96] */
-	os_memcpy(J0, nonce, sizeof(nonce));
-	os_memset(J0 + sizeof(nonce), 0, AES_BLOCK_SIZE - sizeof(nonce));
-	J0[AES_BLOCK_SIZE - 1] = 0x01;
-
-	/* 3. C = GCTR_K(inc_32(J_0), P) */
-	inc32(J0);
-	aes_gctr(aes, J0, frame + hdrlen, len - hdrlen, pos);
-	pos += len - hdrlen;
-
-	/*
-	 * 4. u = 128 * ceil[len(C)/128] - len(C)
-	 *    v = 128 * ceil[len(A)/128] - len(A)
-	 * 5. S = GHASH_H(A || 0^v || C || 0^u || [len(A)]64 || [len(C)]64)
-	 * (i.e., zero padded to block size A || C and lengths of each in bits)
-	 */
-	auth = os_malloc(32 + 16 + len - hdrlen + 8 + 8);
-	if (auth == NULL) {
+	if (aes_gcm_ae(tk, nonce, frame + hdrlen, plen, &aad[2], aad_len,
+		       pos, pos + plen) < 0) {
 		os_free(crypt);
 		return NULL;
 	}
 
-	apos = auth;
-
-	/* Zero-padded AAD */
-	os_memcpy(apos, &aad[2], aad_len);
-	apos += aad_len;
-	padlen = (16 - aad_len % 16) % 16;
-	os_memset(apos, 0, padlen);
-	apos += padlen;
-
-	/* Zero-padded C */
-	os_memcpy(apos, crypt + hdrlen + 8, plen);
-	apos += plen;
-	padlen = (16 - plen % 16) % 16;
-	os_memset(apos, 0, padlen);
-	apos += padlen;
-
-	/* Length of AAD and C in bits */
-	WPA_PUT_BE64(apos, aad_len * 8);
-	apos += 8;
-	WPA_PUT_BE64(apos, plen * 8);
-	apos += 8;
-
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP GHASH_H input", auth, apos - auth);
-	ghash(H, auth, apos - auth, S);
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP S = GHASH_H(...)", S, 16);
-	os_free(auth);
-
-	/* 6. T = MSB_t(GCTR_K(J_0, S)) */
-	J0[AES_BLOCK_SIZE - 1] = 0x01;
-	aes_gctr(aes, J0, S, sizeof(S), pos);
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP MIC", pos, 16);
-
-	/* 7. Return (C, T) */
-
-	wpa_hexdump(MSG_EXCESSIVE, "GCMP encrypted", crypt + hdrlen + 8, plen);
-
-	aes_encrypt_deinit(aes);
+	wpa_hexdump(MSG_EXCESSIVE, "GCMP MIC", pos + plen, 16);
+	wpa_hexdump(MSG_EXCESSIVE, "GCMP encrypted", pos, plen);
 
 	*encrypted_len = hdrlen + 8 + plen + 16;