gost_omac.c

#include <string.h>
#include <openssl/cmac.h>
#include <openssl/conf.h>
#include <openssl/err.h>
#include <openssl/evp.h>

#include "e_gost_err.h"
#include "gost_lcl.h"

#define min(a,b) (((a) < (b)) ? (a) : (b))

typedef struct omac_ctx {
	CMAC_CTX *cmac_ctx;
	size_t   dgst_size;
	int      cipher_nid;
	int      key_set;
} OMAC_CTX;

#define MAX_GOST_OMAC_SIZE 16

static int omac_init(EVP_MD_CTX *ctx, int cipher_nid)
{
    OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);
		memset(c, 0, sizeof(OMAC_CTX));
		c->cipher_nid = cipher_nid;
		c->key_set    = 0;

		switch(cipher_nid) {
			case NID_magma_cbc:
				c->dgst_size = 4;
			break;

			case NID_grasshopper_cbc:
				c->dgst_size = 8;
			break;
		}

    return 1;
}

static int magma_imit_init(EVP_MD_CTX *ctx)
{
    return omac_init(ctx, NID_magma_cbc);
}

static int grasshopper_imit_init(EVP_MD_CTX *ctx)
{
    return omac_init(ctx, NID_grasshopper_cbc);
}

static int omac_imit_update(EVP_MD_CTX *ctx, const void *data, size_t count)
{
    OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);
		if (!c->key_set)
		{
        GOSTerr(GOST_F_OMAC_IMIT_UPDATE, GOST_R_MAC_KEY_NOT_SET);
        return 0;
		}

		return CMAC_Update(c->cmac_ctx, data, count);
}

int omac_imit_final(EVP_MD_CTX *ctx, unsigned char *md)
{
    OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);
		unsigned char mac[MAX_GOST_OMAC_SIZE];
		size_t mac_size = sizeof(mac);

    if (!c->key_set) {
        GOSTerr(GOST_F_OMAC_IMIT_FINAL, GOST_R_MAC_KEY_NOT_SET);
        return 0;
    }

		CMAC_Final(c->cmac_ctx, mac, &mac_size);

    int md_size = EVP_MD_meth_get_result_size(EVP_MD_CTX_md(ctx));
    memcpy(md, mac, min(md_size, c->dgst_size));
    return 1;
}

int omac_imit_copy(EVP_MD_CTX *to, const EVP_MD_CTX *from)
{
    OMAC_CTX *c_to = EVP_MD_CTX_md_data(to);
		const OMAC_CTX *c_from = EVP_MD_CTX_md_data(from);

    if (c_from && c_to) {
			c_to->dgst_size  = c_from->dgst_size;
			c_to->cipher_nid = c_from->cipher_nid;
			c_to->key_set    = c_from->key_set;
    }
		else
		{
			return 0;
		}
                if (!c_from->cmac_ctx) {
                    if (c_to->cmac_ctx) {
                        CMAC_CTX_free(c_to->cmac_ctx);
                        c_to->cmac_ctx = NULL;
                    }
                    return 1;
                }
		if (c_to->cmac_ctx == c_from->cmac_ctx)
		{
		    c_to->cmac_ctx = CMAC_CTX_new();
		}
		return CMAC_CTX_copy(c_to->cmac_ctx, c_from->cmac_ctx);
}

/* Clean up imit ctx */
int omac_imit_cleanup(EVP_MD_CTX *ctx)
{
    OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);

		if (c)
		{
			CMAC_CTX_free(c->cmac_ctx);
	    memset(EVP_MD_CTX_md_data(ctx), 0, sizeof(OMAC_CTX));
		}
    return 1;
}

static int omac_key(OMAC_CTX *c, const EVP_CIPHER *cipher, const unsigned char *key, size_t key_size)
{
	int ret = 0;

	c->cmac_ctx = CMAC_CTX_new();
	if (c->cmac_ctx == NULL)
	{
		GOSTerr(GOST_F_OMAC_KEY, ERR_R_MALLOC_FAILURE);
		return 0;
	}

	ret = CMAC_Init(c->cmac_ctx, key, key_size, cipher, NULL);
	if (ret > 0)
	{
		c->key_set = 1;
	}
	return 1;
}						

int omac_imit_ctrl(EVP_MD_CTX *ctx, int type, int arg, void *ptr)
{
    switch (type) {
    case EVP_MD_CTRL_KEY_LEN:
        *((unsigned int *)(ptr)) = 32;
        return 1;
    case EVP_MD_CTRL_SET_KEY:
				{
					OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);
					const EVP_MD *md = EVP_MD_CTX_md(ctx);
					const EVP_CIPHER *cipher = NULL;

					if (c->cipher_nid == NID_undef)
					{
						switch (EVP_MD_nid(md))
						{
							case NID_magma_mac:
								c->cipher_nid = NID_magma_cbc;
								break;

							case NID_grasshopper_mac:
								c->cipher_nid = NID_grasshopper_cbc;
								break;
						}
					}
					cipher = EVP_get_cipherbynid(c->cipher_nid);

					if (cipher == NULL)
					{
						GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_CIPHER_NOT_FOUND);
					}

					if (EVP_MD_meth_get_init(EVP_MD_CTX_md(ctx)) (ctx) <= 0) {
						GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_MAC_KEY_NOT_SET);
						return 0;
					}
					EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_NO_INIT);

					if (c->key_set)
					{
						GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_BAD_ORDER);
						return 0;
					}

					if (arg == 0) {
						struct gost_mac_key *key = (struct gost_mac_key *)ptr;
						return omac_key(c, cipher, key->key, 32);

					} else if (arg == 32) {
						return omac_key(c, cipher, ptr, 32);
					}
					GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_INVALID_MAC_KEY_SIZE);
					return 0;
				}
    case EVP_MD_CTRL_MAC_LEN:
        {
					OMAC_CTX *c = EVP_MD_CTX_md_data(ctx);
					switch (c->cipher_nid)
					{
						case NID_magma_cbc:
            if (arg < 1 || arg > 8) {
                GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_INVALID_MAC_SIZE);
                return 0;
            }
            c->dgst_size = arg;
						break;
						case NID_grasshopper_cbc:
            if (arg < 1 || arg > 16) {
                GOSTerr(GOST_F_OMAC_IMIT_CTRL, GOST_R_INVALID_MAC_SIZE);
                return 0;
            }
            c->dgst_size = arg;
						break;
						default:
						return 0;
					}
          return 1;
        }

    default:
        return 0;
    }
}

static EVP_MD *_hidden_magma_mac_md = NULL;

EVP_MD *magma_omac(void)
{
    if (_hidden_magma_mac_md == NULL) {
        EVP_MD *md;

        if ((md = EVP_MD_meth_new(NID_magma_mac, NID_undef)) == NULL
            || !EVP_MD_meth_set_result_size(md, 4)
            || !EVP_MD_meth_set_input_blocksize(md, 8)
            || !EVP_MD_meth_set_app_datasize(md, sizeof(OMAC_CTX))
            || !EVP_MD_meth_set_flags(md, 0)
            || !EVP_MD_meth_set_init(md, magma_imit_init)
            || !EVP_MD_meth_set_update(md, omac_imit_update)
            || !EVP_MD_meth_set_final(md, omac_imit_final)
            || !EVP_MD_meth_set_copy(md, omac_imit_copy)
            || !EVP_MD_meth_set_cleanup(md, omac_imit_cleanup)
            || !EVP_MD_meth_set_ctrl(md, omac_imit_ctrl)) {
            EVP_MD_meth_free(md);
            md = NULL;
        }
       _hidden_magma_mac_md = md;
    }
    return _hidden_magma_mac_md;
}

void magma_omac_destroy(void)
{
    EVP_MD_meth_free(_hidden_magma_mac_md);
    _hidden_magma_mac_md = NULL;
}

static EVP_MD *_hidden_grasshopper_mac_md = NULL;

EVP_MD *grasshopper_omac(void)
{
    if (_hidden_grasshopper_mac_md == NULL) {
        EVP_MD *md;

        if ((md = EVP_MD_meth_new(NID_grasshopper_mac, NID_undef)) == NULL
            || !EVP_MD_meth_set_result_size(md, 8)
            || !EVP_MD_meth_set_input_blocksize(md, 8)
            || !EVP_MD_meth_set_app_datasize(md, sizeof(OMAC_CTX))
            || !EVP_MD_meth_set_flags(md, 0)
            || !EVP_MD_meth_set_init(md, grasshopper_imit_init)
            || !EVP_MD_meth_set_update(md, omac_imit_update)
            || !EVP_MD_meth_set_final(md, omac_imit_final)
            || !EVP_MD_meth_set_copy(md, omac_imit_copy)
            || !EVP_MD_meth_set_cleanup(md, omac_imit_cleanup)
            || !EVP_MD_meth_set_ctrl(md, omac_imit_ctrl)) {
            EVP_MD_meth_free(md);
            md = NULL;
        }
       _hidden_grasshopper_mac_md = md;
    }
    return _hidden_grasshopper_mac_md;
}

void grasshopper_omac_destroy(void)
{
    EVP_MD_meth_free(_hidden_grasshopper_mac_md);
    _hidden_grasshopper_mac_md = NULL;
}