

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/sha.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include <openssl/core_dispatch.h>
#include <openssl/proverr.h>
#include "internal/thread_once.h"
#include "prov/providercommon.h"
#include "prov/provider_ctx.h"
#include "prov/provider_util.h"
#include "prov/implementations.h"
#include "drbg_local.h"

static OSSL_FUNC_rand_newctx_fn drbg_hash_new_wrapper;
static OSSL_FUNC_rand_freectx_fn drbg_hash_free;
static OSSL_FUNC_rand_instantiate_fn drbg_hash_instantiate_wrapper;
static OSSL_FUNC_rand_uninstantiate_fn drbg_hash_uninstantiate_wrapper;
static OSSL_FUNC_rand_generate_fn drbg_hash_generate_wrapper;
static OSSL_FUNC_rand_reseed_fn drbg_hash_reseed_wrapper;
static OSSL_FUNC_rand_settable_ctx_params_fn drbg_hash_settable_ctx_params;
static OSSL_FUNC_rand_set_ctx_params_fn drbg_hash_set_ctx_params;
static OSSL_FUNC_rand_gettable_ctx_params_fn drbg_hash_gettable_ctx_params;
static OSSL_FUNC_rand_get_ctx_params_fn drbg_hash_get_ctx_params;
static OSSL_FUNC_rand_verify_zeroization_fn drbg_hash_verify_zeroization;

static int drbg_hash_set_ctx_params_locked(void *vctx, const OSSL_PARAM params[]);


#define HASH_PRNG_MAX_SEEDLEN    (888/8)


#define HASH_PRNG_SMALL_SEEDLEN   (440/8)


#define MAX_BLOCKLEN_USING_SMALL_SEEDLEN (256/8)
#define INBYTE_IGNORE ((unsigned char)0xFF)

typedef struct rand_drbg_hash_st {
    PROV_DIGEST digest;
    EVP_MD_CTX *ctx;
    size_t blocklen;
    unsigned char V[HASH_PRNG_MAX_SEEDLEN];
    unsigned char C[HASH_PRNG_MAX_SEEDLEN];
    
    unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
} PROV_DRBG_HASH;


static int hash_df(PROV_DRBG *drbg, unsigned char *out,
                   const unsigned char inbyte,
                   const unsigned char *in, size_t inlen,
                   const unsigned char *in2, size_t in2len,
                   const unsigned char *in3, size_t in3len)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    EVP_MD_CTX *ctx = hash->ctx;
    unsigned char *vtmp = hash->vtmp;
    
    unsigned char tmp[1 + 4 + 1];
    int tmp_sz = 0;
    size_t outlen = drbg->seedlen;
    size_t num_bits_returned = outlen * 8;
    

    
    tmp[tmp_sz++] = 1;
    
    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 24) & 0xff);
    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 16) & 0xff);
    tmp[tmp_sz++] = (unsigned char)((num_bits_returned >> 8) & 0xff);
    tmp[tmp_sz++] = (unsigned char)(num_bits_returned & 0xff);
    
    if (inbyte != INBYTE_IGNORE)
        tmp[tmp_sz++] = inbyte;

    
    for (;;) {
        
        if (!(EVP_DigestInit_ex(ctx, ossl_prov_digest_md(&hash->digest), NULL)
                && EVP_DigestUpdate(ctx, tmp, tmp_sz)
                && EVP_DigestUpdate(ctx, in, inlen)
                && (in2 == NULL || EVP_DigestUpdate(ctx, in2, in2len))
                && (in3 == NULL || EVP_DigestUpdate(ctx, in3, in3len))))
            return 0;

        if (outlen < hash->blocklen) {
            if (!EVP_DigestFinal(ctx, vtmp, NULL))
                return 0;
            memcpy(out, vtmp, outlen);
            OPENSSL_cleanse(vtmp, hash->blocklen);
            break;
        } else if (!EVP_DigestFinal(ctx, out, NULL)) {
            return 0;
        }

        outlen -= hash->blocklen;
        if (outlen == 0)
            break;
        
        tmp[0]++;
        out += hash->blocklen;
    }
    return 1;
}


static int hash_df1(PROV_DRBG *drbg, unsigned char *out,
                    const unsigned char in_byte,
                    const unsigned char *in1, size_t in1len)
{
    return hash_df(drbg, out, in_byte, in1, in1len, NULL, 0, NULL, 0);
}


static int add_bytes(PROV_DRBG *drbg, unsigned char *dst,
                     unsigned char *in, size_t inlen)
{
    size_t i;
    int result;
    const unsigned char *add;
    unsigned char carry = 0, *d;

    assert(drbg->seedlen >= 1 && inlen >= 1 && inlen <= drbg->seedlen);

    d = &dst[drbg->seedlen - 1];
    add = &in[inlen - 1];

    for (i = inlen; i > 0; i--, d--, add--) {
        result = *d + *add + carry;
        carry = (unsigned char)(result >> 8);
        *d = (unsigned char)(result & 0xff);
    }

    if (carry != 0) {
        
        for (i = drbg->seedlen - inlen; i > 0; --i, d--) {
            *d += 1;     
            if (*d != 0) 
                break;
        }
    }
    return 1;
}


static int add_hash_to_v(PROV_DRBG *drbg, unsigned char inbyte,
                         const unsigned char *adin, size_t adinlen)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    EVP_MD_CTX *ctx = hash->ctx;

    return EVP_DigestInit_ex(ctx, ossl_prov_digest_md(&hash->digest), NULL)
           && EVP_DigestUpdate(ctx, &inbyte, 1)
           && EVP_DigestUpdate(ctx, hash->V, drbg->seedlen)
           && (adin == NULL || EVP_DigestUpdate(ctx, adin, adinlen))
           && EVP_DigestFinal(ctx, hash->vtmp, NULL)
           && add_bytes(drbg, hash->V, hash->vtmp, hash->blocklen);
}


static int hash_gen(PROV_DRBG *drbg, unsigned char *out, size_t outlen)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    unsigned char one = 1;

    if (outlen == 0)
        return 1;
    memcpy(hash->vtmp, hash->V, drbg->seedlen);
    for (;;) {
        if (!EVP_DigestInit_ex(hash->ctx, ossl_prov_digest_md(&hash->digest),
                               NULL)
                || !EVP_DigestUpdate(hash->ctx, hash->vtmp, drbg->seedlen))
            return 0;

        if (outlen < hash->blocklen) {
            if (!EVP_DigestFinal(hash->ctx, hash->vtmp, NULL))
                return 0;
            memcpy(out, hash->vtmp, outlen);
            return 1;
        } else {
            if (!EVP_DigestFinal(hash->ctx, out, NULL))
                return 0;
            outlen -= hash->blocklen;
            if (outlen == 0)
                break;
            out += hash->blocklen;
        }
        add_bytes(drbg, hash->vtmp, &one, 1);
    }
    return 1;
}


static int drbg_hash_instantiate(PROV_DRBG *drbg,
                                 const unsigned char *ent, size_t ent_len,
                                 const unsigned char *nonce, size_t nonce_len,
                                 const unsigned char *pstr, size_t pstr_len)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;

    EVP_MD_CTX_free(hash->ctx);
    hash->ctx = EVP_MD_CTX_new();

    
    return hash->ctx != NULL
           && hash_df(drbg, hash->V, INBYTE_IGNORE,
                      ent, ent_len, nonce, nonce_len, pstr, pstr_len)
           
           && hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen);
}

static int drbg_hash_instantiate_wrapper(void *vdrbg, unsigned int strength,
                                         int prediction_resistance,
                                         const unsigned char *pstr,
                                         size_t pstr_len,
                                         const OSSL_PARAM params[])
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
    int ret = 0;

    if (drbg->lock != NULL && !CRYPTO_THREAD_write_lock(drbg->lock))
        return 0;

    if (!ossl_prov_is_running()
            || !drbg_hash_set_ctx_params_locked(drbg, params))
        goto err;
    ret = ossl_prov_drbg_instantiate(drbg, strength, prediction_resistance,
                                     pstr, pstr_len);
 err:
    if (drbg->lock != NULL)
        CRYPTO_THREAD_unlock(drbg->lock);
    return ret;
}


static int drbg_hash_reseed(PROV_DRBG *drbg,
                            const unsigned char *ent, size_t ent_len,
                            const unsigned char *adin, size_t adin_len)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;

    
    
    if (!hash_df(drbg, hash->C, 0x01, hash->V, drbg->seedlen, ent, ent_len,
                 adin, adin_len))
        return 0;
    memcpy(hash->V, hash->C, drbg->seedlen);
    
    return hash_df1(drbg, hash->C, 0x00, hash->V, drbg->seedlen);
}

static int drbg_hash_reseed_wrapper(void *vdrbg, int prediction_resistance,
                                    const unsigned char *ent, size_t ent_len,
                                    const unsigned char *adin, size_t adin_len)
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;

    return ossl_prov_drbg_reseed(drbg, prediction_resistance, ent, ent_len,
                                 adin, adin_len);
}


static int drbg_hash_generate(PROV_DRBG *drbg,
                              unsigned char *out, size_t outlen,
                              const unsigned char *adin, size_t adin_len)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    unsigned char counter[4];
    int reseed_counter = drbg->generate_counter;

    counter[0] = (unsigned char)((reseed_counter >> 24) & 0xff);
    counter[1] = (unsigned char)((reseed_counter >> 16) & 0xff);
    counter[2] = (unsigned char)((reseed_counter >> 8) & 0xff);
    counter[3] = (unsigned char)(reseed_counter & 0xff);

    return hash->ctx != NULL
           && (adin == NULL
           
               || adin_len == 0
               || add_hash_to_v(drbg, 0x02, adin, adin_len))
           
           && hash_gen(drbg, out, outlen)
           
           && add_hash_to_v(drbg, 0x03, NULL, 0)
           
           
           && add_bytes(drbg, hash->V, hash->C, drbg->seedlen)
           
           && add_bytes(drbg, hash->V, counter, 4);
}

static int drbg_hash_generate_wrapper
    (void *vdrbg, unsigned char *out, size_t outlen, unsigned int strength,
     int prediction_resistance, const unsigned char *adin, size_t adin_len)
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;

    return ossl_prov_drbg_generate(drbg, out, outlen, strength,
                                   prediction_resistance, adin, adin_len);
}

static int drbg_hash_uninstantiate(PROV_DRBG *drbg)
{
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;

    OPENSSL_cleanse(hash->V, sizeof(hash->V));
    OPENSSL_cleanse(hash->C, sizeof(hash->C));
    OPENSSL_cleanse(hash->vtmp, sizeof(hash->vtmp));
    return ossl_prov_drbg_uninstantiate(drbg);
}

static int drbg_hash_uninstantiate_wrapper(void *vdrbg)
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
    int ret;

    if (drbg->lock != NULL && !CRYPTO_THREAD_write_lock(drbg->lock))
        return 0;

    ret = drbg_hash_uninstantiate(drbg);

    if (drbg->lock != NULL)
        CRYPTO_THREAD_unlock(drbg->lock);

    return ret;
}

static int drbg_hash_verify_zeroization(void *vdrbg)
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    int ret = 0;

    if (drbg->lock != NULL && !CRYPTO_THREAD_read_lock(drbg->lock))
        return 0;

    PROV_DRBG_VERIFY_ZEROIZATION(hash->V);
    PROV_DRBG_VERIFY_ZEROIZATION(hash->C);
    PROV_DRBG_VERIFY_ZEROIZATION(hash->vtmp);

    ret = 1;
 err:
    if (drbg->lock != NULL)
        CRYPTO_THREAD_unlock(drbg->lock);
    return ret;
}

static int drbg_hash_new(PROV_DRBG *ctx)
{
    PROV_DRBG_HASH *hash;

    hash = OPENSSL_secure_zalloc(sizeof(*hash));
    if (hash == NULL)
        return 0;

    ctx->data = hash;
    ctx->seedlen = HASH_PRNG_MAX_SEEDLEN;
    ctx->max_entropylen = DRBG_MAX_LENGTH;
    ctx->max_noncelen = DRBG_MAX_LENGTH;
    ctx->max_perslen = DRBG_MAX_LENGTH;
    ctx->max_adinlen = DRBG_MAX_LENGTH;

    
    ctx->max_request = 1 << 16;
    return 1;
}

static void *drbg_hash_new_wrapper(void *provctx, void *parent,
                                   const OSSL_DISPATCH *parent_dispatch)
{
    return ossl_rand_drbg_new(provctx, parent, parent_dispatch,
                              &drbg_hash_new, &drbg_hash_free,
                              &drbg_hash_instantiate, &drbg_hash_uninstantiate,
                              &drbg_hash_reseed, &drbg_hash_generate);
}

static void drbg_hash_free(void *vdrbg)
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
    PROV_DRBG_HASH *hash;

    if (drbg != NULL && (hash = (PROV_DRBG_HASH *)drbg->data) != NULL) {
        EVP_MD_CTX_free(hash->ctx);
        ossl_prov_digest_reset(&hash->digest);
        OPENSSL_secure_clear_free(hash, sizeof(*hash));
    }
    ossl_rand_drbg_free(drbg);
}

static int drbg_hash_get_ctx_params(void *vdrbg, OSSL_PARAM params[])
{
    PROV_DRBG *drbg = (PROV_DRBG *)vdrbg;
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)drbg->data;
    const EVP_MD *md;
    OSSL_PARAM *p;
    int ret = 0, complete = 0;

    if (!ossl_drbg_get_ctx_params_no_lock(drbg, params, &complete))
        return 0;

    if (complete)
        return 1;

    if (drbg->lock != NULL && !CRYPTO_THREAD_read_lock(drbg->lock))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_DRBG_PARAM_DIGEST);
    if (p != NULL) {
        md = ossl_prov_digest_md(&hash->digest);
        if (md == NULL || !OSSL_PARAM_set_utf8_string(p, EVP_MD_get0_name(md)))
            goto err;
    }

    ret = ossl_drbg_get_ctx_params(drbg, params);
 err:
    if (drbg->lock != NULL)
        CRYPTO_THREAD_unlock(drbg->lock);

    return ret;
}

static const OSSL_PARAM *drbg_hash_gettable_ctx_params(ossl_unused void *vctx,
                                                       ossl_unused void *p_ctx)
{
    static const OSSL_PARAM known_gettable_ctx_params[] = {
        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_DIGEST, NULL, 0),
        OSSL_PARAM_DRBG_GETTABLE_CTX_COMMON,
        OSSL_PARAM_END
    };
    return known_gettable_ctx_params;
}

static int drbg_hash_set_ctx_params_locked(void *vctx, const OSSL_PARAM params[])
{
    PROV_DRBG *ctx = (PROV_DRBG *)vctx;
    PROV_DRBG_HASH *hash = (PROV_DRBG_HASH *)ctx->data;
    OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
    const EVP_MD *md;

    if (!ossl_prov_digest_load_from_params(&hash->digest, params, libctx))
        return 0;

    md = ossl_prov_digest_md(&hash->digest);
    if (md != NULL) {
        if (!ossl_drbg_verify_digest(libctx, md))
            return 0;   

        
        hash->blocklen = EVP_MD_get_size(md);
        
        ctx->strength = 64 * (hash->blocklen >> 3);
        if (ctx->strength > 256)
            ctx->strength = 256;
        if (hash->blocklen > MAX_BLOCKLEN_USING_SMALL_SEEDLEN)
            ctx->seedlen = HASH_PRNG_MAX_SEEDLEN;
        else
            ctx->seedlen = HASH_PRNG_SMALL_SEEDLEN;

        ctx->min_entropylen = ctx->strength / 8;
        ctx->min_noncelen = ctx->min_entropylen / 2;
    }

    return ossl_drbg_set_ctx_params(ctx, params);
}

static int drbg_hash_set_ctx_params(void *vctx, const OSSL_PARAM params[])
{
    PROV_DRBG *drbg = (PROV_DRBG *)vctx;
    int ret;

    if (drbg->lock != NULL && !CRYPTO_THREAD_write_lock(drbg->lock))
        return 0;

    ret = drbg_hash_set_ctx_params_locked(vctx, params);

    if (drbg->lock != NULL)
        CRYPTO_THREAD_unlock(drbg->lock);

    return ret;
}

static const OSSL_PARAM *drbg_hash_settable_ctx_params(ossl_unused void *vctx,
                                                       ossl_unused void *p_ctx)
{
    static const OSSL_PARAM known_settable_ctx_params[] = {
        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_PROPERTIES, NULL, 0),
        OSSL_PARAM_utf8_string(OSSL_DRBG_PARAM_DIGEST, NULL, 0),
        OSSL_PARAM_DRBG_SETTABLE_CTX_COMMON,
        OSSL_PARAM_END
    };
    return known_settable_ctx_params;
}

const OSSL_DISPATCH ossl_drbg_hash_functions[] = {
    { OSSL_FUNC_RAND_NEWCTX, (void(*)(void))drbg_hash_new_wrapper },
    { OSSL_FUNC_RAND_FREECTX, (void(*)(void))drbg_hash_free },
    { OSSL_FUNC_RAND_INSTANTIATE,
      (void(*)(void))drbg_hash_instantiate_wrapper },
    { OSSL_FUNC_RAND_UNINSTANTIATE,
      (void(*)(void))drbg_hash_uninstantiate_wrapper },
    { OSSL_FUNC_RAND_GENERATE, (void(*)(void))drbg_hash_generate_wrapper },
    { OSSL_FUNC_RAND_RESEED, (void(*)(void))drbg_hash_reseed_wrapper },
    { OSSL_FUNC_RAND_ENABLE_LOCKING, (void(*)(void))ossl_drbg_enable_locking },
    { OSSL_FUNC_RAND_LOCK, (void(*)(void))ossl_drbg_lock },
    { OSSL_FUNC_RAND_UNLOCK, (void(*)(void))ossl_drbg_unlock },
    { OSSL_FUNC_RAND_SETTABLE_CTX_PARAMS,
      (void(*)(void))drbg_hash_settable_ctx_params },
    { OSSL_FUNC_RAND_SET_CTX_PARAMS, (void(*)(void))drbg_hash_set_ctx_params },
    { OSSL_FUNC_RAND_GETTABLE_CTX_PARAMS,
      (void(*)(void))drbg_hash_gettable_ctx_params },
    { OSSL_FUNC_RAND_GET_CTX_PARAMS, (void(*)(void))drbg_hash_get_ctx_params },
    { OSSL_FUNC_RAND_VERIFY_ZEROIZATION,
      (void(*)(void))drbg_hash_verify_zeroization },
    { OSSL_FUNC_RAND_GET_SEED, (void(*)(void))ossl_drbg_get_seed },
    { OSSL_FUNC_RAND_CLEAR_SEED, (void(*)(void))ossl_drbg_clear_seed },
    OSSL_DISPATCH_END
};
