/src/openssl33/crypto/cmac/cmac.c

Source
/*
 * Copyright 2010-2024 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * CMAC low level APIs are deprecated for public use, but still ok for internal
 * use.
 */
#include "internal/deprecated.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "internal/cryptlib.h"
#include <openssl/cmac.h>
#include <openssl/err.h>

#define LOCAL_BUF_SIZE 2048
struct CMAC_CTX_st {
    /* Cipher context to use */
    EVP_CIPHER_CTX *cctx;
    /* Keys k1 and k2 */
    unsigned char k1[EVP_MAX_BLOCK_LENGTH];
    unsigned char k2[EVP_MAX_BLOCK_LENGTH];
    /* Temporary block */
    unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
    /* Last (possibly partial) block */
    unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
    /* Number of bytes in last block: -1 means context not initialised */
    int nlast_block;
};

/* Make temporary keys K1 and K2 */

static void make_kn(unsigned char *k1, const unsigned char *l, int bl)
{
    int i;
    unsigned char c = l[0], carry = c >> 7, cnext;

    /* Shift block to left, including carry */
    for (i = 0; i < bl - 1; i++, c = cnext)
        k1[i] = (c << 1) | ((cnext = l[i + 1]) >> 7);

    /* If MSB set fixup with R */
    k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
}

CMAC_CTX *CMAC_CTX_new(void)
{
    CMAC_CTX *ctx;

    if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL)
        return NULL;
    ctx->cctx = EVP_CIPHER_CTX_new();
    if (ctx->cctx == NULL) {
        OPENSSL_free(ctx);
        return NULL;
    }
    ctx->nlast_block = -1;
    return ctx;
}

void CMAC_CTX_cleanup(CMAC_CTX *ctx)
{
    EVP_CIPHER_CTX_reset(ctx->cctx);
    OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
    OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
    ctx->nlast_block = -1;
}

EVP_CIPHER_CTX *CMAC_CTX_get0_cipher_ctx(CMAC_CTX *ctx)
{
    return ctx->cctx;
}

void CMAC_CTX_free(CMAC_CTX *ctx)
{
    if (!ctx)
        return;
    CMAC_CTX_cleanup(ctx);
    EVP_CIPHER_CTX_free(ctx->cctx);
    OPENSSL_free(ctx);
}

int CMAC_CTX_copy(CMAC_CTX *out, const CMAC_CTX *in)
{
    int bl;

    if (in->nlast_block == -1)
        return 0;
    if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) == 0)
        return 0;
    if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
        return 0;
    memcpy(out->k1, in->k1, bl);
    memcpy(out->k2, in->k2, bl);
    memcpy(out->tbl, in->tbl, bl);
    memcpy(out->last_block, in->last_block, bl);
    out->nlast_block = in->nlast_block;
    return 1;
}

int CMAC_Init(CMAC_CTX *ctx, const void *key, size_t keylen,
    const EVP_CIPHER *cipher, ENGINE *impl)
{
    static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
    int block_len;

    /* All zeros means restart */
    if (!key && !cipher && !impl && keylen == 0) {
        /* Not initialised */
        if (ctx->nlast_block == -1)
            return 0;
        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
            return 0;
        block_len = EVP_CIPHER_CTX_get_block_size(ctx->cctx);
        if (block_len == 0)
            return 0;
        memset(ctx->tbl, 0, block_len);
        ctx->nlast_block = 0;
        return 1;
    }
    /* Initialise context */
    if (cipher != NULL) {
        /* Ensure we can't use this ctx until we also have a key */
        ctx->nlast_block = -1;
        if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
            return 0;
    }
    /* Non-NULL key means initialisation complete */
    if (key != NULL) {
        int bl;

        /* If anything fails then ensure we can't use this ctx */
        ctx->nlast_block = -1;
        if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
            return 0;
        if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
            return 0;
        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
            return 0;
        if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
            return 0;
        if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
            return 0;
        make_kn(ctx->k1, ctx->tbl, bl);
        make_kn(ctx->k2, ctx->k1, bl);
        OPENSSL_cleanse(ctx->tbl, bl);
        /* Reset context again ready for first data block */
        if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
            return 0;
        /* Zero tbl so resume works */
        memset(ctx->tbl, 0, bl);
        ctx->nlast_block = 0;
    }
    return 1;
}

int CMAC_Update(CMAC_CTX *ctx, const void *in, size_t dlen)
{
    const unsigned char *data = in;
    int bl;
    size_t max_burst_blocks, cipher_blocks;
    unsigned char buf[LOCAL_BUF_SIZE];

    if (ctx->nlast_block == -1)
        return 0;
    if (dlen == 0)
        return 1;
    if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
        return 0;
    /* Copy into partial block if we need to */
    if (ctx->nlast_block > 0) {
        size_t nleft;

        nleft = bl - ctx->nlast_block;
        if (dlen < nleft)
            nleft = dlen;
        memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
        dlen -= nleft;
        ctx->nlast_block += nleft;
        /* If no more to process return */
        if (dlen == 0)
            return 1;
        data += nleft;
        /* Else not final block so encrypt it */
        if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
            return 0;
    }
    /* Encrypt all but one of the complete blocks left */

    max_burst_blocks = LOCAL_BUF_SIZE / bl;
    cipher_blocks = (dlen - 1) / bl;
    if (max_burst_blocks == 0) {
        /*
         * When block length is greater than local buffer size,
         * use ctx->tbl as cipher output.
         */
        while (dlen > (size_t)bl) {
            if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
                return 0;
            dlen -= bl;
            data += bl;
        }
    } else {
        while (cipher_blocks > max_burst_blocks) {
            if (EVP_Cipher(ctx->cctx, buf, data, max_burst_blocks * bl) <= 0)
                return 0;
            dlen -= max_burst_blocks * bl;
            data += max_burst_blocks * bl;
            cipher_blocks -= max_burst_blocks;
        }
        if (cipher_blocks > 0) {
            if (EVP_Cipher(ctx->cctx, buf, data, cipher_blocks * bl) <= 0)
                return 0;
            dlen -= cipher_blocks * bl;
            data += cipher_blocks * bl;
            memcpy(ctx->tbl, &buf[(cipher_blocks - 1) * bl], bl);
        }
    }
    /* Copy any data left to last block buffer */
    memcpy(ctx->last_block, data, dlen);
    ctx->nlast_block = dlen;
    return 1;
}

int CMAC_Final(CMAC_CTX *ctx, unsigned char *out, size_t *poutlen)
{
    int i, bl, lb;

    if (ctx->nlast_block == -1)
        return 0;
    if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
        return 0;
    if (poutlen != NULL)
        *poutlen = (size_t)bl;
    if (!out)
        return 1;
    lb = ctx->nlast_block;
    /* Is last block complete? */
    if (lb == bl) {
        for (i = 0; i < bl; i++)
            out[i] = ctx->last_block[i] ^ ctx->k1[i];
    } else {
        ctx->last_block[lb] = 0x80;
        if (bl - lb > 1)
            memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
        for (i = 0; i < bl; i++)
            out[i] = ctx->last_block[i] ^ ctx->k2[i];
    }
    if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
        OPENSSL_cleanse(out, bl);
        return 0;
    }
    return 1;
}

int CMAC_resume(CMAC_CTX *ctx)
{
    if (ctx->nlast_block == -1)
        return 0;
    /*
     * The buffer "tbl" contains the last fully encrypted block which is the
     * last IV (or all zeroes if no last encrypted block). The last block has
     * not been modified since CMAC_final(). So reinitialising using the last
     * decrypted block will allow CMAC to continue after calling
     * CMAC_Final().
     */
    return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
}

Coverage Report

Created: 2025-12-31 06:58

Line	Count	Source
1		/*
2		* Copyright 2010-2024 The OpenSSL Project Authors. All Rights Reserved.
3		*
4		* Licensed under the Apache License 2.0 (the "License"). You may not use
5		* this file except in compliance with the License. You can obtain a copy
6		* in the file LICENSE in the source distribution or at
7		* https://www.openssl.org/source/license.html
8		*/
9
10		/*
11		* CMAC low level APIs are deprecated for public use, but still ok for internal
12		* use.
13		*/
14		#include "internal/deprecated.h"
15
16		#include <stdio.h>
17		#include <stdlib.h>
18		#include <string.h>
19		#include "internal/cryptlib.h"
20		#include <openssl/cmac.h>
21		#include <openssl/err.h>
22
23	660	#define LOCAL_BUF_SIZE 2048
24		struct CMAC_CTX_st {
25		/* Cipher context to use */
26		EVP_CIPHER_CTX *cctx;
27		/* Keys k1 and k2 */
28		unsigned char k1[EVP_MAX_BLOCK_LENGTH];
29		unsigned char k2[EVP_MAX_BLOCK_LENGTH];
30		/* Temporary block */
31		unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
32		/* Last (possibly partial) block */
33		unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
34		/* Number of bytes in last block: -1 means context not initialised */
35		int nlast_block;
36		};
37
38		/* Make temporary keys K1 and K2 */
39
40		static void make_kn(unsigned char k1, const unsigned char l, int bl)
41	294	{
42	294	int i;
43	294	unsigned char c = l[0], carry = c >> 7, cnext;
44
45		/* Shift block to left, including carry */
46	3.40k	for (i = 0; i < bl - 1; i++, c = cnext)
47	3.11k	k1[i] = (c << 1) \| ((cnext = l[i + 1]) >> 7);
48
49		/* If MSB set fixup with R */
50	294	k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
51	294	}
52
53		CMAC_CTX *CMAC_CTX_new(void)
54	547	{
55	547	CMAC_CTX *ctx;
56
57	547	if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL)
58	0	return NULL;
59	547	ctx->cctx = EVP_CIPHER_CTX_new();
60	547	if (ctx->cctx == NULL) {
61	0	OPENSSL_free(ctx);
62	0	return NULL;
63	0	}
64	547	ctx->nlast_block = -1;
65	547	return ctx;
66	547	}
67
68		void CMAC_CTX_cleanup(CMAC_CTX *ctx)
69	547	{
70	547	EVP_CIPHER_CTX_reset(ctx->cctx);
71	547	OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
72	547	OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
73	547	OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
74	547	OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
75	547	ctx->nlast_block = -1;
76	547	}
77
78		EVP_CIPHER_CTX CMAC_CTX_get0_cipher_ctx(CMAC_CTX ctx)
79	294	{
80	294	return ctx->cctx;
81	294	}
82
83		void CMAC_CTX_free(CMAC_CTX *ctx)
84	547	{
85	547	if (!ctx)
86	0	return;
87	547	CMAC_CTX_cleanup(ctx);
88	547	EVP_CIPHER_CTX_free(ctx->cctx);
89	547	OPENSSL_free(ctx);
90	547	}
91
92		int CMAC_CTX_copy(CMAC_CTX out, const CMAC_CTX in)
93	218	{
94	218	int bl;
95
96	218	if (in->nlast_block == -1)
97	0	return 0;
98	218	if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) == 0)
99	0	return 0;
100	218	if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
101	0	return 0;
102	218	memcpy(out->k1, in->k1, bl);
103	218	memcpy(out->k2, in->k2, bl);
104	218	memcpy(out->tbl, in->tbl, bl);
105	218	memcpy(out->last_block, in->last_block, bl);
106	218	out->nlast_block = in->nlast_block;
107	218	return 1;
108	218	}
109
110		int CMAC_Init(CMAC_CTX ctx, const void key, size_t keylen,
111		const EVP_CIPHER cipher, ENGINE impl)
112	0	{
113	0	static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
114	0	int block_len;
115
116		/* All zeros means restart */
117	0	if (!key && !cipher && !impl && keylen == 0) {
118		/* Not initialised */
119	0	if (ctx->nlast_block == -1)
120	0	return 0;
121	0	if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
122	0	return 0;
123	0	block_len = EVP_CIPHER_CTX_get_block_size(ctx->cctx);
124	0	if (block_len == 0)
125	0	return 0;
126	0	memset(ctx->tbl, 0, block_len);
127	0	ctx->nlast_block = 0;
128	0	return 1;
129	0	}
130		/* Initialise context */
131	0	if (cipher != NULL) {
132		/* Ensure we can't use this ctx until we also have a key */
133	0	ctx->nlast_block = -1;
134	0	if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
135	0	return 0;
136	0	}
137		/* Non-NULL key means initialisation complete */
138	0	if (key != NULL) {
139	0	int bl;
140
141		/* If anything fails then ensure we can't use this ctx */
142	0	ctx->nlast_block = -1;
143	0	if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
144	0	return 0;
145	0	if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
146	0	return 0;
147	0	if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
148	0	return 0;
149	0	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
150	0	return 0;
151	0	if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
152	0	return 0;
153	0	make_kn(ctx->k1, ctx->tbl, bl);
154	0	make_kn(ctx->k2, ctx->k1, bl);
155	0	OPENSSL_cleanse(ctx->tbl, bl);
156		/* Reset context again ready for first data block */
157	0	if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
158	0	return 0;
159		/* Zero tbl so resume works */
160	0	memset(ctx->tbl, 0, bl);
161	0	ctx->nlast_block = 0;
162	0	}
163	0	return 1;
164	0	}
165
166		int CMAC_Update(CMAC_CTX ctx, const void in, size_t dlen)
167	814	{
168	814	const unsigned char *data = in;
169	814	int bl;
170	814	size_t max_burst_blocks, cipher_blocks;
171	814	unsigned char buf[LOCAL_BUF_SIZE];
172
173	814	if (ctx->nlast_block == -1)
174	0	return 0;
175	814	if (dlen == 0)
176	22	return 1;
177	792	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
178	0	return 0;
179		/* Copy into partial block if we need to */
180	792	if (ctx->nlast_block > 0) {
181	574	size_t nleft;
182
183	574	nleft = bl - ctx->nlast_block;
184	574	if (dlen < nleft)
185	124	nleft = dlen;
186	574	memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
187	574	dlen -= nleft;
188	574	ctx->nlast_block += nleft;
189		/* If no more to process return */
190	574	if (dlen == 0)
191	132	return 1;
192	442	data += nleft;
193		/* Else not final block so encrypt it */
194	442	if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
195	0	return 0;
196	442	}
197		/* Encrypt all but one of the complete blocks left */
198
199	660	max_burst_blocks = LOCAL_BUF_SIZE / bl;
200	660	cipher_blocks = (dlen - 1) / bl;
201	660	if (max_burst_blocks == 0) {
202		/*
203		* When block length is greater than local buffer size,
204		* use ctx->tbl as cipher output.
205		*/
206	0	while (dlen > (size_t)bl) {
207	0	if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
208	0	return 0;
209	0	dlen -= bl;
210	0	data += bl;
211	0	}
212	660	} else {
213	4.72k	while (cipher_blocks > max_burst_blocks) {
214	4.06k	if (EVP_Cipher(ctx->cctx, buf, data, max_burst_blocks * bl) <= 0)
215	0	return 0;
216	4.06k	dlen -= max_burst_blocks * bl;
217	4.06k	data += max_burst_blocks * bl;
218	4.06k	cipher_blocks -= max_burst_blocks;
219	4.06k	}
220	660	if (cipher_blocks > 0) {
221	366	if (EVP_Cipher(ctx->cctx, buf, data, cipher_blocks * bl) <= 0)
222	0	return 0;
223	366	dlen -= cipher_blocks * bl;
224	366	data += cipher_blocks * bl;
225	366	memcpy(ctx->tbl, &buf[(cipher_blocks - 1) * bl], bl);
226	366	}
227	660	}
228		/* Copy any data left to last block buffer */
229	660	memcpy(ctx->last_block, data, dlen);
230	660	ctx->nlast_block = dlen;
231	660	return 1;
232	660	}
233
234		int CMAC_Final(CMAC_CTX ctx, unsigned char out, size_t *poutlen)
235	218	{
236	218	int i, bl, lb;
237
238	218	if (ctx->nlast_block == -1)
239	0	return 0;
240	218	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) == 0)
241	0	return 0;
242	218	if (poutlen != NULL)
243	218	*poutlen = (size_t)bl;
244	218	if (!out)
245	0	return 1;
246	218	lb = ctx->nlast_block;
247		/* Is last block complete? */
248	218	if (lb == bl) {
249	282	for (i = 0; i < bl; i++)
250	256	out[i] = ctx->last_block[i] ^ ctx->k1[i];
251	192	} else {
252	192	ctx->last_block[lb] = 0x80;
253	192	if (bl - lb > 1)
254	166	memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
255	2.20k	for (i = 0; i < bl; i++)
256	2.01k	out[i] = ctx->last_block[i] ^ ctx->k2[i];
257	192	}
258	218	if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
259	0	OPENSSL_cleanse(out, bl);
260	0	return 0;
261	0	}
262	218	return 1;
263	218	}
264
265		int CMAC_resume(CMAC_CTX *ctx)
266	0	{
267	0	if (ctx->nlast_block == -1)
268	0	return 0;
269		/*
270		* The buffer "tbl" contains the last fully encrypted block which is the
271		* last IV (or all zeroes if no last encrypted block). The last block has
272		* not been modified since CMAC_final(). So reinitialising using the last
273		* decrypted block will allow CMAC to continue after calling
274		* CMAC_Final().
275		*/
276	0	return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
277	0	}