crypto_libtomcrypt.c

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/*
 * WPA Supplicant / Crypto wrapper for LibTomCrypt (for internal TLSv1)
 * Copyright (c) 2005-2006, Jouni Malinen <j@w1.fi>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Alternatively, this software may be distributed under the terms of BSD
 * license.
 *
 * See README and COPYING for more details.
 */

#include "includes.h"
#include <tomcrypt.h>

#include "common.h"
#include "crypto.h"

#ifndef mp_init_multi
#define mp_init_multi                ltc_init_multi
#define mp_clear_multi               ltc_deinit_multi
#define mp_unsigned_bin_size(a)      ltc_mp.unsigned_size(a)
#define mp_to_unsigned_bin(a, b)     ltc_mp.unsigned_write(a, b)
#define mp_read_unsigned_bin(a, b, c) ltc_mp.unsigned_read(a, b, c)
#define mp_exptmod(a,b,c,d)          ltc_mp.exptmod(a,b,c,d)
#endif


int md4_vector(size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
{
        hash_state md;
        size_t i;

        md4_init(&md);
        for (i = 0; i < num_elem; i++)
                md4_process(&md, addr[i], len[i]);
        md4_done(&md, mac);
        return 0;
}


void des_encrypt(const u8 *clear, const u8 *key, u8 *cypher)
{
        u8 pkey[8], next, tmp;
        int i;
        symmetric_key skey;

        /* Add parity bits to the key */
        next = 0;
        for (i = 0; i < 7; i++) {
                tmp = key[i];
                pkey[i] = (tmp >> i) | next | 1;
                next = tmp << (7 - i);
        }
        pkey[i] = next | 1;

        des_setup(pkey, 8, 0, &skey);
        des_ecb_encrypt(clear, cypher, &skey);
        des_done(&skey);
}


int md5_vector(size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
{
        hash_state md;
        size_t i;

        md5_init(&md);
        for (i = 0; i < num_elem; i++)
                md5_process(&md, addr[i], len[i]);
        md5_done(&md, mac);
        return 0;
}


int sha1_vector(size_t num_elem, const u8 *addr[], const size_t *len, u8 *mac)
{
        hash_state md;
        size_t i;

        sha1_init(&md);
        for (i = 0; i < num_elem; i++)
                sha1_process(&md, addr[i], len[i]);
        sha1_done(&md, mac);
        return 0;
}


void * aes_encrypt_init(const u8 *key, size_t len)
{
        symmetric_key *skey;
        skey = os_malloc(sizeof(*skey));
        if (skey == NULL)
                return NULL;
        if (aes_setup(key, len, 0, skey) != CRYPT_OK) {
                os_free(skey);
                return NULL;
        }
        return skey;
}


void aes_encrypt(void *ctx, const u8 *plain, u8 *crypt)
{
        symmetric_key *skey = ctx;
        aes_ecb_encrypt(plain, crypt, skey);
}


void aes_encrypt_deinit(void *ctx)
{
        symmetric_key *skey = ctx;
        aes_done(skey);
        os_free(skey);
}


void * aes_decrypt_init(const u8 *key, size_t len)
{
        symmetric_key *skey;
        skey = os_malloc(sizeof(*skey));
        if (skey == NULL)
                return NULL;
        if (aes_setup(key, len, 0, skey) != CRYPT_OK) {
                os_free(skey);
                return NULL;
        }
        return skey;
}


void aes_decrypt(void *ctx, const u8 *crypt, u8 *plain)
{
        symmetric_key *skey = ctx;
        aes_ecb_encrypt(plain, (u8 *) crypt, skey);
}


void aes_decrypt_deinit(void *ctx)
{
        symmetric_key *skey = ctx;
        aes_done(skey);
        os_free(skey);
}


struct crypto_hash {
        enum crypto_hash_alg alg;
        int error;
        union {
                hash_state md;
                hmac_state hmac;
        } u;
};


struct crypto_hash * crypto_hash_init(enum crypto_hash_alg alg, const u8 *key,
                                      size_t key_len)
{
        struct crypto_hash *ctx;

        ctx = os_zalloc(sizeof(*ctx));
        if (ctx == NULL)
                return NULL;

        ctx->alg = alg;

        switch (alg) {
        case CRYPTO_HASH_ALG_MD5:
                if (md5_init(&ctx->u.md) != CRYPT_OK)
                        goto fail;
                break;
        case CRYPTO_HASH_ALG_SHA1:
                if (sha1_init(&ctx->u.md) != CRYPT_OK)
                        goto fail;
                break;
        case CRYPTO_HASH_ALG_HMAC_MD5:
                if (hmac_init(&ctx->u.hmac, find_hash("md5"), key, key_len) !=
                    CRYPT_OK)
                        goto fail;
                break;
        case CRYPTO_HASH_ALG_HMAC_SHA1:
                if (hmac_init(&ctx->u.hmac, find_hash("sha1"), key, key_len) !=
                    CRYPT_OK)
                        goto fail;
                break;
        default:
                goto fail;
        }

        return ctx;

fail:
        os_free(ctx);
        return NULL;
}

void crypto_hash_update(struct crypto_hash *ctx, const u8 *data, size_t len)
{
        if (ctx == NULL || ctx->error)
                return;

        switch (ctx->alg) {
        case CRYPTO_HASH_ALG_MD5:
                ctx->error = md5_process(&ctx->u.md, data, len) != CRYPT_OK;
                break;
        case CRYPTO_HASH_ALG_SHA1:
                ctx->error = sha1_process(&ctx->u.md, data, len) != CRYPT_OK;
                break;
        case CRYPTO_HASH_ALG_HMAC_MD5:
        case CRYPTO_HASH_ALG_HMAC_SHA1:
                ctx->error = hmac_process(&ctx->u.hmac, data, len) != CRYPT_OK;
                break;
        }
}


int crypto_hash_finish(struct crypto_hash *ctx, u8 *mac, size_t *len)
{
        int ret = 0;
        unsigned long clen;

        if (ctx == NULL)
                return -2;

        if (mac == NULL || len == NULL) {
                os_free(ctx);
                return 0;
        }

        if (ctx->error) {
                os_free(ctx);
                return -2;
        }

        switch (ctx->alg) {
        case CRYPTO_HASH_ALG_MD5:
                if (*len < 16) {
                        *len = 16;
                        os_free(ctx);
                        return -1;
                }
                *len = 16;
                if (md5_done(&ctx->u.md, mac) != CRYPT_OK)
                        ret = -2;
                break;
        case CRYPTO_HASH_ALG_SHA1:
                if (*len < 20) {
                        *len = 20;
                        os_free(ctx);
                        return -1;
                }
                *len = 20;
                if (sha1_done(&ctx->u.md, mac) != CRYPT_OK)
                        ret = -2;
                break;
        case CRYPTO_HASH_ALG_HMAC_SHA1:
                if (*len < 20) {
                        *len = 20;
                        os_free(ctx);
                        return -1;
                }
                /* continue */
        case CRYPTO_HASH_ALG_HMAC_MD5:
                if (*len < 16) {
                        *len = 16;
                        os_free(ctx);
                        return -1;
                }
                clen = *len;
                if (hmac_done(&ctx->u.hmac, mac, &clen) != CRYPT_OK) {
                        os_free(ctx);
                        return -1;
                }
                *len = clen;
                break;
        default:
                ret = -2;
                break;
        }

        os_free(ctx);

        return ret;
}


struct crypto_cipher {
        int rc4;
        union {
                symmetric_CBC cbc;
                struct {
                        size_t used_bytes;
                        u8 key[16];
                        size_t keylen;
                } rc4;
        } u;
};


struct crypto_cipher * crypto_cipher_init(enum crypto_cipher_alg alg,
                                          const u8 *iv, const u8 *key,
                                          size_t key_len)
{       
        struct crypto_cipher *ctx;
        int idx, res, rc4 = 0;

        switch (alg) {
        case CRYPTO_CIPHER_ALG_AES:
                idx = find_cipher("aes");
                break;
        case CRYPTO_CIPHER_ALG_3DES:
                idx = find_cipher("3des");
                break;
        case CRYPTO_CIPHER_ALG_DES:
                idx = find_cipher("des");
                break;
        case CRYPTO_CIPHER_ALG_RC2:
                idx = find_cipher("rc2");
                break;
        case CRYPTO_CIPHER_ALG_RC4:
                idx = -1;
                rc4 = 1;
                break;
        default:
                return NULL;
        }

        ctx = os_zalloc(sizeof(*ctx));
        if (ctx == NULL)
                return NULL;

        if (rc4) {
                ctx->rc4 = 1;
                if (key_len > sizeof(ctx->u.rc4.key)) {
                        os_free(ctx);
                        return NULL;
                }
                ctx->u.rc4.keylen = key_len;
                os_memcpy(ctx->u.rc4.key, key, key_len);
        } else {
                res = cbc_start(idx, iv, key, key_len, 0, &ctx->u.cbc);
                if (res != CRYPT_OK) {
                        wpa_printf(MSG_DEBUG, "LibTomCrypt: Cipher start "
                                   "failed: %s", error_to_string(res));
                        os_free(ctx);
                        return NULL;
                }
        }

        return ctx;
}

int crypto_cipher_encrypt(struct crypto_cipher *ctx, const u8 *plain,
                          u8 *crypt, size_t len)
{
        int res;

        if (ctx->rc4) {
                if (plain != crypt)
                        os_memcpy(crypt, plain, len);
                rc4_skip(ctx->u.rc4.key, ctx->u.rc4.keylen,
                         ctx->u.rc4.used_bytes, crypt, len);
                ctx->u.rc4.used_bytes += len;
                return 0;
        }

        res = cbc_encrypt(plain, crypt, len, &ctx->u.cbc);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_DEBUG, "LibTomCrypt: CBC encryption "
                           "failed: %s", error_to_string(res));
                return -1;
        }
        return 0;
}


int crypto_cipher_decrypt(struct crypto_cipher *ctx, const u8 *crypt,
                          u8 *plain, size_t len)
{
        int res;

        if (ctx->rc4) {
                if (plain != crypt)
                        os_memcpy(plain, crypt, len);
                rc4_skip(ctx->u.rc4.key, ctx->u.rc4.keylen,
                         ctx->u.rc4.used_bytes, plain, len);
                ctx->u.rc4.used_bytes += len;
                return 0;
        }

        res = cbc_decrypt(crypt, plain, len, &ctx->u.cbc);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_DEBUG, "LibTomCrypt: CBC decryption "
                           "failed: %s", error_to_string(res));
                return -1;
        }

        return 0;
}


void crypto_cipher_deinit(struct crypto_cipher *ctx)
{
        if (!ctx->rc4)
                cbc_done(&ctx->u.cbc);
        os_free(ctx);
}


struct crypto_public_key {
        rsa_key rsa;
};

struct crypto_private_key {
        rsa_key rsa;
};


struct crypto_public_key * crypto_public_key_import(const u8 *key, size_t len)
{
        int res;
        struct crypto_public_key *pk;

        pk = os_zalloc(sizeof(*pk));
        if (pk == NULL)
                return NULL;

        res = rsa_import(key, len, &pk->rsa);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_ERROR, "LibTomCrypt: Failed to import "
                           "public key (res=%d '%s')",
                           res, error_to_string(res));
                os_free(pk);
                return NULL;
        }

        if (pk->rsa.type != PK_PUBLIC) {
                wpa_printf(MSG_ERROR, "LibTomCrypt: Public key was not of "
                           "correct type");
                rsa_free(&pk->rsa);
                os_free(pk);
                return NULL;
        }

        return pk;
}


struct crypto_private_key * crypto_private_key_import(const u8 *key,
                                                      size_t len,
                                                      const char *passwd)
{
        int res;
        struct crypto_private_key *pk;

        pk = os_zalloc(sizeof(*pk));
        if (pk == NULL)
                return NULL;

        res = rsa_import(key, len, &pk->rsa);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_ERROR, "LibTomCrypt: Failed to import "
                           "private key (res=%d '%s')",
                           res, error_to_string(res));
                os_free(pk);
                return NULL;
        }

        if (pk->rsa.type != PK_PRIVATE) {
                wpa_printf(MSG_ERROR, "LibTomCrypt: Private key was not of "
                           "correct type");
                rsa_free(&pk->rsa);
                os_free(pk);
                return NULL;
        }

        return pk;
}


struct crypto_public_key * crypto_public_key_from_cert(const u8 *buf,
                                                       size_t len)
{
        /* No X.509 support in LibTomCrypt */
        return NULL;
}


static int pkcs1_generate_encryption_block(u8 block_type, size_t modlen,
                                           const u8 *in, size_t inlen,
                                           u8 *out, size_t *outlen)
{
        size_t ps_len;
        u8 *pos;

        /*
         * PKCS #1 v1.5, 8.1:
         *
         * EB = 00 || BT || PS || 00 || D
         * BT = 00 or 01 for private-key operation; 02 for public-key operation
         * PS = k-3-||D||; at least eight octets
         * (BT=0: PS=0x00, BT=1: PS=0xff, BT=2: PS=pseudorandom non-zero)
         * k = length of modulus in octets (modlen)
         */

        if (modlen < 12 || modlen > *outlen || inlen > modlen - 11) {
                wpa_printf(MSG_DEBUG, "PKCS #1: %s - Invalid buffer "
                           "lengths (modlen=%lu outlen=%lu inlen=%lu)",
                           __func__, (unsigned long) modlen,
                           (unsigned long) *outlen,
                           (unsigned long) inlen);
                return -1;
        }

        pos = out;
        *pos++ = 0x00;
        *pos++ = block_type; /* BT */
        ps_len = modlen - inlen - 3;
        switch (block_type) {
        case 0:
                os_memset(pos, 0x00, ps_len);
                pos += ps_len;
                break;
        case 1:
                os_memset(pos, 0xff, ps_len);
                pos += ps_len;
                break;
        case 2:
                if (os_get_random(pos, ps_len) < 0) {
                        wpa_printf(MSG_DEBUG, "PKCS #1: %s - Failed to get "
                                   "random data for PS", __func__);
                        return -1;
                }
                while (ps_len--) {
                        if (*pos == 0x00)
                                *pos = 0x01;
                        pos++;
                }
                break;
        default:
                wpa_printf(MSG_DEBUG, "PKCS #1: %s - Unsupported block type "
                           "%d", __func__, block_type);
                return -1;
        }
        *pos++ = 0x00;
        os_memcpy(pos, in, inlen); /* D */

        return 0;
}


static int crypto_rsa_encrypt_pkcs1(int block_type, rsa_key *key, int key_type,
                                    const u8 *in, size_t inlen,
                                    u8 *out, size_t *outlen)
{
        unsigned long len, modlen;
        int res;

        modlen = mp_unsigned_bin_size(key->N);

        if (pkcs1_generate_encryption_block(block_type, modlen, in, inlen,
                                            out, outlen) < 0)
                return -1;

        len = *outlen;
        res = rsa_exptmod(out, modlen, out, &len, key_type, key);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_DEBUG, "LibTomCrypt: rsa_exptmod failed: %s",
                           error_to_string(res));
                return -1;
        }
        *outlen = len;

        return 0;
}


int crypto_public_key_encrypt_pkcs1_v15(struct crypto_public_key *key,
                                        const u8 *in, size_t inlen,
                                        u8 *out, size_t *outlen)
{
        return crypto_rsa_encrypt_pkcs1(2, &key->rsa, PK_PUBLIC, in, inlen,
                                        out, outlen);
}


int crypto_private_key_sign_pkcs1(struct crypto_private_key *key,
                                  const u8 *in, size_t inlen,
                                  u8 *out, size_t *outlen)
{
        return crypto_rsa_encrypt_pkcs1(1, &key->rsa, PK_PRIVATE, in, inlen,
                                        out, outlen);
}


void crypto_public_key_free(struct crypto_public_key *key)
{
        if (key) {
                rsa_free(&key->rsa);
                os_free(key);
        }
}


void crypto_private_key_free(struct crypto_private_key *key)
{
        if (key) {
                rsa_free(&key->rsa);
                os_free(key);
        }
}


int crypto_public_key_decrypt_pkcs1(struct crypto_public_key *key,
                                    const u8 *crypt, size_t crypt_len,
                                    u8 *plain, size_t *plain_len)
{
        int res;
        unsigned long len;
        u8 *pos;

        len = *plain_len;
        res = rsa_exptmod(crypt, crypt_len, plain, &len, PK_PUBLIC,
                          &key->rsa);
        if (res != CRYPT_OK) {
                wpa_printf(MSG_DEBUG, "LibTomCrypt: rsa_exptmod failed: %s",
                           error_to_string(res));
                return -1;
        }

        /*
         * PKCS #1 v1.5, 8.1:
         *
         * EB = 00 || BT || PS || 00 || D
         * BT = 01
         * PS = k-3-||D|| times FF
         * k = length of modulus in octets
         */

        if (len < 3 + 8 + 16 /* min hash len */ ||
            plain[0] != 0x00 || plain[1] != 0x01 || plain[2] != 0xff) {
                wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB "
                           "structure");
                return -1;
        }

        pos = plain + 3;
        while (pos < plain + len && *pos == 0xff)
                pos++;
        if (pos - plain - 2 < 8) {
                /* PKCS #1 v1.5, 8.1: At least eight octets long PS */
                wpa_printf(MSG_INFO, "LibTomCrypt: Too short signature "
                           "padding");
                return -1;
        }

        if (pos + 16 /* min hash len */ >= plain + len || *pos != 0x00) {
                wpa_printf(MSG_INFO, "LibTomCrypt: Invalid signature EB "
                           "structure (2)");
                return -1;
        }
        pos++;
        len -= pos - plain;

        /* Strip PKCS #1 header */
        os_memmove(plain, pos, len);
        *plain_len = len;

        return 0;
}


int crypto_global_init(void)
{
        ltc_mp = tfm_desc;
        /* TODO: only register algorithms that are really needed */
        if (register_hash(&md4_desc) < 0 ||
            register_hash(&md5_desc) < 0 ||
            register_hash(&sha1_desc) < 0 ||
            register_cipher(&aes_desc) < 0 ||
            register_cipher(&des_desc) < 0 ||
            register_cipher(&des3_desc) < 0) {
                wpa_printf(MSG_ERROR, "TLSv1: Failed to register "
                           "hash/cipher functions");
                return -1;
        }

        return 0;
}


void crypto_global_deinit(void)
{
}


#ifdef CONFIG_MODEXP

int crypto_mod_exp(const u8 *base, size_t base_len,
                   const u8 *power, size_t power_len,
                   const u8 *modulus, size_t modulus_len,
                   u8 *result, size_t *result_len)
{
        void *b, *p, *m, *r;

        if (mp_init_multi(&b, &p, &m, &r, NULL) != CRYPT_OK)
                return -1;

        if (mp_read_unsigned_bin(b, (u8 *) base, base_len) != CRYPT_OK ||
            mp_read_unsigned_bin(p, (u8 *) power, power_len) != CRYPT_OK ||
            mp_read_unsigned_bin(m, (u8 *) modulus, modulus_len) != CRYPT_OK)
                goto fail;

        if (mp_exptmod(b, p, m, r) != CRYPT_OK)
                goto fail;

        *result_len = mp_unsigned_bin_size(r);
        if (mp_to_unsigned_bin(r, result) != CRYPT_OK)
                goto fail;

        mp_clear_multi(b, p, m, r, NULL);
        return 0;

fail:
        mp_clear_multi(b, p, m, r, NULL);
        return -1;
}

#endif /* CONFIG_MODEXP */