crypto_aes_cbc.c

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// SPDX-FileCopyrightText: 2016-2017 rakholiyajenish.07 <rakholiyajenish.07@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_lib.h>
#include <rz_crypto.h>
#include <rz_util.h>
#include <aes.h>
 
typedef struct aes_cbc_context_t {
    struct aes_ctx st;
    bool iv_set;
    ut8 iv[32];
} AesCbcCtx;
 
static void encryptaes(struct aes_ctx *ctx, ut8 *in, ut8 *out) {
    switch (ctx->key_size) {
    case AES128_KEY_SIZE:
        aes128_encrypt(&ctx->u.ctx128, AES_BLOCK_SIZE, out, in);
        break;
    case AES192_KEY_SIZE:
        aes192_encrypt(&ctx->u.ctx192, AES_BLOCK_SIZE, out, in);
        break;
    case AES256_KEY_SIZE:
        aes256_encrypt(&ctx->u.ctx256, AES_BLOCK_SIZE, out, in);
        break;
    default:
        rz_warn_if_reached();
        break;
    }
}
 
static void decryptaes(struct aes_ctx *ctx, ut8 *in, ut8 *out) {
    switch (ctx->key_size) {
    case AES128_KEY_SIZE:
        aes128_decrypt(&ctx->u.ctx128, AES_BLOCK_SIZE, out, in);
        break;
    case AES192_KEY_SIZE:
        aes192_decrypt(&ctx->u.ctx192, AES_BLOCK_SIZE, out, in);
        break;
    case AES256_KEY_SIZE:
        aes256_decrypt(&ctx->u.ctx256, AES_BLOCK_SIZE, out, in);
        break;
    default:
        rz_warn_if_reached();
        break;
    }
}
 
static bool aes_cbc_set_key(RzCrypto *cry, const ut8 *key, int keylen, int mode, int direction) {
    rz_return_val_if_fail(cry->user && key, false);
 
    if (!(keylen == AES128_KEY_SIZE || keylen == AES192_KEY_SIZE || keylen == AES256_KEY_SIZE)) {
        return false;
    }
    AesCbcCtx *ctx = (AesCbcCtx *)cry->user;
 
    ctx->st.key_size = keylen;
    switch (keylen) {
    case AES128_KEY_SIZE:
        if (direction == RZ_CRYPTO_DIR_ENCRYPT) {
            aes128_set_encrypt_key(&ctx->st.u.ctx128, key);
        } else {
            aes128_set_decrypt_key(&ctx->st.u.ctx128, key);
        }
        break;
    case AES192_KEY_SIZE:
        if (direction == RZ_CRYPTO_DIR_ENCRYPT) {
            aes192_set_encrypt_key(&ctx->st.u.ctx192, key);
        } else {
            aes192_set_decrypt_key(&ctx->st.u.ctx192, key);
        }
        break;
    case AES256_KEY_SIZE:
        if (direction == RZ_CRYPTO_DIR_ENCRYPT) {
            aes256_set_encrypt_key(&ctx->st.u.ctx256, key);
        } else {
            aes256_set_decrypt_key(&ctx->st.u.ctx256, key);
        }
        break;
    default:
        rz_warn_if_reached();
        break;
    }
    cry->dir = direction;
    return true;
}
 
static int aes_cbc_get_key_size(RzCrypto *cry) {
    rz_return_val_if_fail(cry->user, 0);
    AesCbcCtx *ctx = (AesCbcCtx *)cry->user;
 
    return ctx->st.key_size;
}
 
static bool aes_cbc_set_iv(RzCrypto *cry, const ut8 *iv_src, int ivlen) {
    rz_return_val_if_fail(cry->user && iv_src, false);
    AesCbcCtx *ctx = (AesCbcCtx *)cry->user;
 
    if (ivlen != AES_BLOCK_SIZE) {
        return false;
    }
    memcpy(ctx->iv, iv_src, AES_BLOCK_SIZE);
    ctx->iv_set = true;
    return true;
}
 
static bool aes_cbc_use(const char *algo) {
    return algo && !strcmp(algo, "aes-cbc");
}
 
static bool update(RzCrypto *cry, const ut8 *buf, int len) {
    rz_return_val_if_fail(cry->user, false);
    AesCbcCtx *ctx = (AesCbcCtx *)cry->user;
 
    if (len < 1) {
        return false;
    }
 
    if (!ctx->iv_set) {
        eprintf("IV not set. Use -I [iv]\n");
        return false;
    }
    const int diff = (AES_BLOCK_SIZE - (len % AES_BLOCK_SIZE)) % AES_BLOCK_SIZE;
    const int size = len + diff;
    const int blocks = size / AES_BLOCK_SIZE;
 
    ut8 *const obuf = calloc(1, size);
    if (!obuf) {
        return false;
    }
 
    ut8 *const ibuf = calloc(1, size);
    if (!ibuf) {
        free(obuf);
        return false;
    }
 
    memset(ibuf, 0, size);
    memcpy(ibuf, buf, len);
 
    if (diff) {
        ibuf[len] = 8; // 0b1000;
    }
 
    int i, j;
    if (cry->dir == RZ_CRYPTO_DIR_ENCRYPT) {
        for (i = 0; i < blocks; i++) {
            for (j = 0; j < AES_BLOCK_SIZE; j++) {
                ibuf[i * AES_BLOCK_SIZE + j] ^= ctx->iv[j];
            }
            encryptaes(&ctx->st, ibuf + AES_BLOCK_SIZE * i, obuf + AES_BLOCK_SIZE * i);
            memcpy(ctx->iv, obuf + AES_BLOCK_SIZE * i, AES_BLOCK_SIZE);
        }
    } else {
        for (i = 0; i < blocks; i++) {
            decryptaes(&ctx->st, ibuf + AES_BLOCK_SIZE * i, obuf + AES_BLOCK_SIZE * i);
            for (j = 0; j < AES_BLOCK_SIZE; j++) {
                obuf[i * AES_BLOCK_SIZE + j] ^= ctx->iv[j];
            }
            memcpy(ctx->iv, buf + AES_BLOCK_SIZE * i, AES_BLOCK_SIZE);
        }
    }
 
    rz_crypto_append(cry, obuf, size);
    free(obuf);
    free(ibuf);
    return true;
}
 
static bool final(RzCrypto *cry, const ut8 *buf, int len) {
    return update(cry, buf, len);
}
 
static bool aes_cbc_init(RzCrypto *cry) {
    rz_return_val_if_fail(cry, false);
 
    cry->user = RZ_NEW0(AesCbcCtx);
    return cry->user != NULL;
}
 
static bool aes_cbc_fini(RzCrypto *cry) {
    rz_return_val_if_fail(cry, false);
 
    free(cry->user);
    return true;
}
 
RzCryptoPlugin rz_crypto_plugin_aes_cbc = {
    .name = "aes-cbc",
    .author = "rakholiyajenish.07",
    .license = "LGPL-3",
    .set_key = aes_cbc_set_key,
    .get_key_size = aes_cbc_get_key_size,
    .set_iv = aes_cbc_set_iv,
    .use = aes_cbc_use,
    .update = update,
    .final = final,
    .init = aes_cbc_init,
    .fini = aes_cbc_fini,
};
 
#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
    .type = RZ_LIB_TYPE_CRYPTO,
    .data = &rz_crypto_plugin_aes_cbc,
    .version = RZ_VERSION
};
#endif