


#include "internal/deprecated.h"
#include "internal/nelem.h"

#include <openssl/crypto.h>
#include <openssl/evp.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/rsa.h>
#include <openssl/params.h>
#include <openssl/err.h>
#include "crypto/rsa.h"
#include <openssl/proverr.h>
#include "internal/nelem.h"
#include "prov/provider_ctx.h"
#include "prov/implementations.h"
#include "prov/securitycheck.h"

static OSSL_FUNC_kem_newctx_fn rsakem_newctx;
static OSSL_FUNC_kem_encapsulate_init_fn rsakem_encapsulate_init;
static OSSL_FUNC_kem_encapsulate_fn rsakem_generate;
static OSSL_FUNC_kem_decapsulate_init_fn rsakem_decapsulate_init;
static OSSL_FUNC_kem_decapsulate_fn rsakem_recover;
static OSSL_FUNC_kem_freectx_fn rsakem_freectx;
static OSSL_FUNC_kem_dupctx_fn rsakem_dupctx;
static OSSL_FUNC_kem_get_ctx_params_fn rsakem_get_ctx_params;
static OSSL_FUNC_kem_gettable_ctx_params_fn rsakem_gettable_ctx_params;
static OSSL_FUNC_kem_set_ctx_params_fn rsakem_set_ctx_params;
static OSSL_FUNC_kem_settable_ctx_params_fn rsakem_settable_ctx_params;


#define KEM_OP_UNDEFINED   -1
#define KEM_OP_RSASVE       0


typedef struct {
    OSSL_LIB_CTX *libctx;
    RSA *rsa;
    int op;
} PROV_RSA_CTX;

static const OSSL_ITEM rsakem_opname_id_map[] = {
    { KEM_OP_RSASVE, OSSL_KEM_PARAM_OPERATION_RSASVE },
};

static int name2id(const char *name, const OSSL_ITEM *map, size_t sz)
{
    size_t i;

    if (name == NULL)
        return -1;

    for (i = 0; i < sz; ++i) {
        if (OPENSSL_strcasecmp(map[i].ptr, name) == 0)
            return map[i].id;
    }
    return -1;
}

static int rsakem_opname2id(const char *name)
{
    return name2id(name, rsakem_opname_id_map, OSSL_NELEM(rsakem_opname_id_map));
}

static void *rsakem_newctx(void *provctx)
{
    PROV_RSA_CTX *prsactx =  OPENSSL_zalloc(sizeof(PROV_RSA_CTX));

    if (prsactx == NULL)
        return NULL;
    prsactx->libctx = PROV_LIBCTX_OF(provctx);
    prsactx->op = KEM_OP_UNDEFINED;

    return prsactx;
}

static void rsakem_freectx(void *vprsactx)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    RSA_free(prsactx->rsa);
    OPENSSL_free(prsactx);
}

static void *rsakem_dupctx(void *vprsactx)
{
    PROV_RSA_CTX *srcctx = (PROV_RSA_CTX *)vprsactx;
    PROV_RSA_CTX *dstctx;

    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
    if (dstctx == NULL)
        return NULL;

    *dstctx = *srcctx;
    if (dstctx->rsa != NULL && !RSA_up_ref(dstctx->rsa)) {
        OPENSSL_free(dstctx);
        return NULL;
    }
    return dstctx;
}

static int rsakem_init(void *vprsactx, void *vrsa,
                       const OSSL_PARAM params[], int operation)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx == NULL || vrsa == NULL)
        return 0;

    if (!ossl_rsa_check_key(prsactx->libctx, vrsa, operation))
        return 0;

    if (!RSA_up_ref(vrsa))
        return 0;
    RSA_free(prsactx->rsa);
    prsactx->rsa = vrsa;

    return rsakem_set_ctx_params(prsactx, params);
}

static int rsakem_encapsulate_init(void *vprsactx, void *vrsa,
                                   const OSSL_PARAM params[])
{
    return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_ENCAPSULATE);
}

static int rsakem_decapsulate_init(void *vprsactx, void *vrsa,
                                   const OSSL_PARAM params[])
{
    return rsakem_init(vprsactx, vrsa, params, EVP_PKEY_OP_DECAPSULATE);
}

static int rsakem_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
{
    PROV_RSA_CTX *ctx = (PROV_RSA_CTX *)vprsactx;

    return ctx != NULL;
}

static const OSSL_PARAM known_gettable_rsakem_ctx_params[] = {
    OSSL_PARAM_END
};

static const OSSL_PARAM *rsakem_gettable_ctx_params(ossl_unused void *vprsactx,
                                                    ossl_unused void *provctx)
{
    return known_gettable_rsakem_ctx_params;
}

static int rsakem_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    const OSSL_PARAM *p;
    int op;

    if (prsactx == NULL)
        return 0;
    if (params == NULL)
        return 1;


    p = OSSL_PARAM_locate_const(params, OSSL_KEM_PARAM_OPERATION);
    if (p != NULL) {
        if (p->data_type != OSSL_PARAM_UTF8_STRING)
            return 0;
        op = rsakem_opname2id(p->data);
        if (op < 0)
            return 0;
        prsactx->op = op;
    }
    return 1;
}

static const OSSL_PARAM known_settable_rsakem_ctx_params[] = {
    OSSL_PARAM_utf8_string(OSSL_KEM_PARAM_OPERATION, NULL, 0),
    OSSL_PARAM_END
};

static const OSSL_PARAM *rsakem_settable_ctx_params(ossl_unused void *vprsactx,
                                                    ossl_unused void *provctx)
{
    return known_settable_rsakem_ctx_params;
}


static int rsasve_gen_rand_bytes(RSA *rsa_pub,
                                 unsigned char *out, int outlen)
{
    int ret = 0;
    BN_CTX *bnctx;
    BIGNUM *z, *nminus3;

    bnctx = BN_CTX_secure_new_ex(ossl_rsa_get0_libctx(rsa_pub));
    if (bnctx == NULL)
        return 0;

    
    BN_CTX_start(bnctx);
    nminus3 = BN_CTX_get(bnctx);
    z = BN_CTX_get(bnctx);
    ret = (z != NULL
           && (BN_copy(nminus3, RSA_get0_n(rsa_pub)) != NULL)
           && BN_sub_word(nminus3, 3)
           && BN_priv_rand_range_ex(z, nminus3, 0, bnctx)
           && BN_add_word(z, 2)
           && (BN_bn2binpad(z, out, outlen) == outlen));
    BN_CTX_end(bnctx);
    BN_CTX_free(bnctx);
    return ret;
}


static int rsasve_generate(PROV_RSA_CTX *prsactx,
                           unsigned char *out, size_t *outlen,
                           unsigned char *secret, size_t *secretlen)
{
    int ret;
    size_t nlen;

    
    nlen = RSA_size(prsactx->rsa);

    if (out == NULL) {
        if (nlen == 0) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
            return 0;
        }
        if (outlen == NULL && secretlen == NULL)
            return 0;
        if (outlen != NULL)
            *outlen = nlen;
        if (secretlen != NULL)
            *secretlen = nlen;
        return 1;
    }
    
    if (!rsasve_gen_rand_bytes(prsactx->rsa, secret, nlen))
        return 0;

    
    ret = RSA_public_encrypt(nlen, secret, out, prsactx->rsa, RSA_NO_PADDING);
    if (ret) {
        ret = 1;
        if (outlen != NULL)
            *outlen = nlen;
        if (secretlen != NULL)
            *secretlen = nlen;
    } else {
        OPENSSL_cleanse(secret, nlen);
    }
    return ret;
}


static int rsasve_recover(PROV_RSA_CTX *prsactx,
                          unsigned char *out, size_t *outlen,
                          const unsigned char *in, size_t inlen)
{
    size_t nlen;

    
    nlen = RSA_size(prsactx->rsa);

    if (out == NULL) {
        if (nlen == 0) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY);
            return 0;
        }
        *outlen = nlen;
        return 1;
    }

    
    if (inlen != nlen) {
        ERR_raise(ERR_LIB_PROV, PROV_R_BAD_LENGTH);
        return 0;
    }
    
    return (RSA_private_decrypt(inlen, in, out, prsactx->rsa, RSA_NO_PADDING) > 0);
}

static int rsakem_generate(void *vprsactx, unsigned char *out, size_t *outlen,
                           unsigned char *secret, size_t *secretlen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    switch (prsactx->op) {
        case KEM_OP_RSASVE:
            return rsasve_generate(prsactx, out, outlen, secret, secretlen);
        default:
            return -2;
    }
}

static int rsakem_recover(void *vprsactx, unsigned char *out, size_t *outlen,
                          const unsigned char *in, size_t inlen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    switch (prsactx->op) {
        case KEM_OP_RSASVE:
            return rsasve_recover(prsactx, out, outlen, in, inlen);
        default:
            return -2;
    }
}

const OSSL_DISPATCH ossl_rsa_asym_kem_functions[] = {
    { OSSL_FUNC_KEM_NEWCTX, (void (*)(void))rsakem_newctx },
    { OSSL_FUNC_KEM_ENCAPSULATE_INIT,
      (void (*)(void))rsakem_encapsulate_init },
    { OSSL_FUNC_KEM_ENCAPSULATE, (void (*)(void))rsakem_generate },
    { OSSL_FUNC_KEM_DECAPSULATE_INIT,
      (void (*)(void))rsakem_decapsulate_init },
    { OSSL_FUNC_KEM_DECAPSULATE, (void (*)(void))rsakem_recover },
    { OSSL_FUNC_KEM_FREECTX, (void (*)(void))rsakem_freectx },
    { OSSL_FUNC_KEM_DUPCTX, (void (*)(void))rsakem_dupctx },
    { OSSL_FUNC_KEM_GET_CTX_PARAMS,
      (void (*)(void))rsakem_get_ctx_params },
    { OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS,
      (void (*)(void))rsakem_gettable_ctx_params },
    { OSSL_FUNC_KEM_SET_CTX_PARAMS,
      (void (*)(void))rsakem_set_ctx_params },
    { OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS,
      (void (*)(void))rsakem_settable_ctx_params },
    OSSL_DISPATCH_END
};
