/src/openssl30/crypto/cmac/cmac.c

Source (jump to first uncovered line)
/*
 * Copyright 2010-2022 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>

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) {
        ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
        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 };

    /* 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;
        memset(ctx->tbl, 0, EVP_CIPHER_CTX_get_block_size(ctx->cctx));
        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;

    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 */
    while (dlen > (size_t)bl) {
        if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
            return 0;
        dlen -= bl;
        data += 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: 2025-06-13 06:58

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2010-2022 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		struct CMAC_CTX_st {
24		/* Cipher context to use */
25		EVP_CIPHER_CTX *cctx;
26		/* Keys k1 and k2 */
27		unsigned char k1[EVP_MAX_BLOCK_LENGTH];
28		unsigned char k2[EVP_MAX_BLOCK_LENGTH];
29		/* Temporary block */
30		unsigned char tbl[EVP_MAX_BLOCK_LENGTH];
31		/* Last (possibly partial) block */
32		unsigned char last_block[EVP_MAX_BLOCK_LENGTH];
33		/* Number of bytes in last block: -1 means context not initialised */
34		int nlast_block;
35		};
36
37		/* Make temporary keys K1 and K2 */
38
39		static void make_kn(unsigned char k1, const unsigned char l, int bl)
40	14	{
41	14	int i;
42	14	unsigned char c = l[0], carry = c >> 7, cnext;
43
44		/* Shift block to left, including carry */
45	208	for (i = 0; i < bl - 1; i++, c = cnext)
46	194	k1[i] = (c << 1) \| ((cnext = l[i + 1]) >> 7);
47
48		/* If MSB set fixup with R */
49	14	k1[i] = (c << 1) ^ ((0 - carry) & (bl == 16 ? 0x87 : 0x1b));
50	14	}
51
52		CMAC_CTX *CMAC_CTX_new(void)
53	46	{
54	46	CMAC_CTX *ctx;
55
56	46	if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL) {
57	0	ERR_raise(ERR_LIB_CRYPTO, ERR_R_MALLOC_FAILURE);
58	0	return NULL;
59	0	}
60	46	ctx->cctx = EVP_CIPHER_CTX_new();
61	46	if (ctx->cctx == NULL) {
62	0	OPENSSL_free(ctx);
63	0	return NULL;
64	0	}
65	46	ctx->nlast_block = -1;
66	46	return ctx;
67	46	}
68
69		void CMAC_CTX_cleanup(CMAC_CTX *ctx)
70	46	{
71	46	EVP_CIPHER_CTX_reset(ctx->cctx);
72	46	OPENSSL_cleanse(ctx->tbl, EVP_MAX_BLOCK_LENGTH);
73	46	OPENSSL_cleanse(ctx->k1, EVP_MAX_BLOCK_LENGTH);
74	46	OPENSSL_cleanse(ctx->k2, EVP_MAX_BLOCK_LENGTH);
75	46	OPENSSL_cleanse(ctx->last_block, EVP_MAX_BLOCK_LENGTH);
76	46	ctx->nlast_block = -1;
77	46	}
78
79		EVP_CIPHER_CTX CMAC_CTX_get0_cipher_ctx(CMAC_CTX ctx)
80	0	{
81	0	return ctx->cctx;
82	0	}
83
84		void CMAC_CTX_free(CMAC_CTX *ctx)
85	46	{
86	46	if (!ctx)
87	0	return;
88	46	CMAC_CTX_cleanup(ctx);
89	46	EVP_CIPHER_CTX_free(ctx->cctx);
90	46	OPENSSL_free(ctx);
91	46	}
92
93		int CMAC_CTX_copy(CMAC_CTX out, const CMAC_CTX in)
94	0	{
95	0	int bl;
96
97	0	if (in->nlast_block == -1)
98	0	return 0;
99	0	if ((bl = EVP_CIPHER_CTX_get_block_size(in->cctx)) < 0)
100	0	return 0;
101	0	if (!EVP_CIPHER_CTX_copy(out->cctx, in->cctx))
102	0	return 0;
103	0	memcpy(out->k1, in->k1, bl);
104	0	memcpy(out->k2, in->k2, bl);
105	0	memcpy(out->tbl, in->tbl, bl);
106	0	memcpy(out->last_block, in->last_block, bl);
107	0	out->nlast_block = in->nlast_block;
108	0	return 1;
109	0	}
110
111		int CMAC_Init(CMAC_CTX ctx, const void key, size_t keylen,
112		const EVP_CIPHER cipher, ENGINE impl)
113	0	{
114	0	static const unsigned char zero_iv[EVP_MAX_BLOCK_LENGTH] = { 0 };
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	memset(ctx->tbl, 0, EVP_CIPHER_CTX_get_block_size(ctx->cctx));
124	0	ctx->nlast_block = 0;
125	0	return 1;
126	0	}
127		/* Initialise context */
128	0	if (cipher != NULL) {
129		/* Ensure we can't use this ctx until we also have a key */
130	0	ctx->nlast_block = -1;
131	0	if (!EVP_EncryptInit_ex(ctx->cctx, cipher, impl, NULL, NULL))
132	0	return 0;
133	0	}
134		/* Non-NULL key means initialisation complete */
135	0	if (key != NULL) {
136	0	int bl;
137
138		/* If anything fails then ensure we can't use this ctx */
139	0	ctx->nlast_block = -1;
140	0	if (EVP_CIPHER_CTX_get0_cipher(ctx->cctx) == NULL)
141	0	return 0;
142	0	if (EVP_CIPHER_CTX_set_key_length(ctx->cctx, keylen) <= 0)
143	0	return 0;
144	0	if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, key, zero_iv))
145	0	return 0;
146	0	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
147	0	return 0;
148	0	if (EVP_Cipher(ctx->cctx, ctx->tbl, zero_iv, bl) <= 0)
149	0	return 0;
150	0	make_kn(ctx->k1, ctx->tbl, bl);
151	0	make_kn(ctx->k2, ctx->k1, bl);
152	0	OPENSSL_cleanse(ctx->tbl, bl);
153		/* Reset context again ready for first data block */
154	0	if (!EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, zero_iv))
155	0	return 0;
156		/* Zero tbl so resume works */
157	0	memset(ctx->tbl, 0, bl);
158	0	ctx->nlast_block = 0;
159	0	}
160	0	return 1;
161	0	}
162
163		int CMAC_Update(CMAC_CTX ctx, const void in, size_t dlen)
164	0	{
165	0	const unsigned char *data = in;
166	0	int bl;
167
168	0	if (ctx->nlast_block == -1)
169	0	return 0;
170	0	if (dlen == 0)
171	0	return 1;
172	0	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
173	0	return 0;
174		/* Copy into partial block if we need to */
175	0	if (ctx->nlast_block > 0) {
176	0	size_t nleft;
177
178	0	nleft = bl - ctx->nlast_block;
179	0	if (dlen < nleft)
180	0	nleft = dlen;
181	0	memcpy(ctx->last_block + ctx->nlast_block, data, nleft);
182	0	dlen -= nleft;
183	0	ctx->nlast_block += nleft;
184		/* If no more to process return */
185	0	if (dlen == 0)
186	0	return 1;
187	0	data += nleft;
188		/* Else not final block so encrypt it */
189	0	if (EVP_Cipher(ctx->cctx, ctx->tbl, ctx->last_block, bl) <= 0)
190	0	return 0;
191	0	}
192		/* Encrypt all but one of the complete blocks left */
193	0	while (dlen > (size_t)bl) {
194	0	if (EVP_Cipher(ctx->cctx, ctx->tbl, data, bl) <= 0)
195	0	return 0;
196	0	dlen -= bl;
197	0	data += bl;
198	0	}
199		/* Copy any data left to last block buffer */
200	0	memcpy(ctx->last_block, data, dlen);
201	0	ctx->nlast_block = dlen;
202	0	return 1;
203
204	0	}
205
206		int CMAC_Final(CMAC_CTX ctx, unsigned char out, size_t *poutlen)
207	0	{
208	0	int i, bl, lb;
209
210	0	if (ctx->nlast_block == -1)
211	0	return 0;
212	0	if ((bl = EVP_CIPHER_CTX_get_block_size(ctx->cctx)) < 0)
213	0	return 0;
214	0	if (poutlen != NULL)
215	0	*poutlen = (size_t)bl;
216	0	if (!out)
217	0	return 1;
218	0	lb = ctx->nlast_block;
219		/* Is last block complete? */
220	0	if (lb == bl) {
221	0	for (i = 0; i < bl; i++)
222	0	out[i] = ctx->last_block[i] ^ ctx->k1[i];
223	0	} else {
224	0	ctx->last_block[lb] = 0x80;
225	0	if (bl - lb > 1)
226	0	memset(ctx->last_block + lb + 1, 0, bl - lb - 1);
227	0	for (i = 0; i < bl; i++)
228	0	out[i] = ctx->last_block[i] ^ ctx->k2[i];
229	0	}
230	0	if (EVP_Cipher(ctx->cctx, out, out, bl) <= 0) {
231	0	OPENSSL_cleanse(out, bl);
232	0	return 0;
233	0	}
234	0	return 1;
235	0	}
236
237		int CMAC_resume(CMAC_CTX *ctx)
238	0	{
239	0	if (ctx->nlast_block == -1)
240	0	return 0;
241		/*
242		* The buffer "tbl" contains the last fully encrypted block which is the
243		* last IV (or all zeroes if no last encrypted block). The last block has
244		* not been modified since CMAC_final(). So reinitialising using the last
245		* decrypted block will allow CMAC to continue after calling
246		* CMAC_Final().
247		*/
248	0	return EVP_EncryptInit_ex(ctx->cctx, NULL, NULL, NULL, ctx->tbl);
249	0	}