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#include "rw.h"

#include <contrib/libs/openssl/include/openssl/evp.h>

//#define DBG_FUZZING

int RwApply(const int flen, const unsigned char* from, unsigned char* to, const TRwKey* rw) {
    int i, j, num, k, r = -1;
    BN_CTX* ctx = NULL;
    BIGNUM *f = NULL, *ret = NULL;

    if ((ctx = BN_CTX_secure_new()) == NULL)
        goto err;
    BN_CTX_start(ctx);

    f = BN_CTX_get(ctx);
    ret = BN_CTX_get(ctx);

    num = BN_num_bytes(rw->N);

    if (num <= 0)
        goto err;

    if (!f || !ret)
        goto err;

    if (BN_bin2bn(from, flen, f) == NULL)
        goto err;
    if (BN_ucmp(f, rw->N) >= 0)
        goto err;

    if (!rw->Meth->RwApply(ret, f, ctx, rw))
        goto err;

    j = BN_num_bytes(ret);
    if (num < j || j < 0)
        goto err;

    i = BN_bn2bin(ret, to + num - j);
    if (i < 0 || i > num)
        goto err;

    for (k = 0; k < (num - i); k++)
        to[k] = 0;
    r = num;

err:
    if (ctx != NULL) {
        BN_CTX_end(ctx);
        BN_CTX_free(ctx);
    }
    return r;
}

int RwPssrSignHash(const unsigned char* from, unsigned char* to, TRwKey* rw, const EVP_MD* md) {
    unsigned char* padding = NULL;
    int result = 0;

    if (from == NULL || to == NULL || rw == NULL || md == NULL)
        return 0;

    int digest_size = EVP_MD_size(md);
    int sig_size = RwModSize(rw);

    if (digest_size <= 0 || sig_size <= 0)
        return 0;

    int tries = 50;
    do {
        if (padding != NULL) {
            free(padding);
#ifdef DBG_FUZZING
            fprintf(stderr, "Padding regenerating required\n");
#endif
        }

        padding = malloc(sig_size);
        if (padding == NULL)
            return 0;

        if (!RwPaddingAddPssr(rw, padding, from, md, digest_size))
            goto err;
    } while (padding[0] == 0x00 && tries-- > 0);

    result = RwNoPaddingSign(sig_size, padding, to, rw);

err:
    if (padding != NULL)
        free(padding);

    return result;
}

int RwPssrSignMsg(const int msgLen, const unsigned char* msg, unsigned char* to, TRwKey* rw, const EVP_MD* md) {
    EVP_MD_CTX* mdctx = NULL;
    unsigned char* digest = NULL;
    unsigned int digestLen;
    int result = 0;

    if (msg == NULL || to == NULL || rw == NULL || md == NULL)
        goto err;

    if (rw->P == NULL || rw->Q == NULL)
        goto err;

    if ((mdctx = EVP_MD_CTX_create()) == NULL)
        goto err;

    if (1 != EVP_DigestInit_ex(mdctx, md, NULL))
        goto err;

    if (1 != EVP_DigestUpdate(mdctx, msg, msgLen))
        goto err;

    if ((digest = (unsigned char*)malloc(EVP_MD_size(md))) == NULL)
        goto err;

    if (1 != EVP_DigestFinal_ex(mdctx, digest, &digestLen))
        goto err;

    result = RwPssrSignHash(digest, to, rw, md);

err:
    if (mdctx != NULL)
        EVP_MD_CTX_destroy(mdctx);
    if (digest != NULL)
        free(digest);

    return result;
}

int RwPssrVerifyHash(const unsigned char* from, const unsigned char* sig, const int sig_len, const TRwKey* rw, const EVP_MD* md) {
    unsigned char* buffer = NULL;
    int buffer_len;
    int salt_size;
    int result = 0;

    if (from == NULL || sig == NULL || rw == NULL || md == NULL)
        return 0;

    if (rw->N == NULL || rw->Meth == NULL)
        return 0;

    salt_size = EVP_MD_size(md);
    if (salt_size <= 0)
        return 0;

    buffer_len = RwModSize(rw);
    if (buffer_len <= 0)
        return 0;

    buffer = (unsigned char*)malloc(buffer_len);
    if (buffer == NULL)
        return 0;

    if (RwApply(sig_len, sig, buffer, rw) <= 0)
        goto err;

    if (RwVerifyPssr(rw, from, md, buffer, salt_size) <= 0)
        goto err;

    result = 1;

err:
    if (buffer != NULL)
        free(buffer);

    return result;
}

int RwPssrVerifyMsg(const int msgLen, const unsigned char* msg, const unsigned char* sig, const int sig_len, const TRwKey* rw, const EVP_MD* md) {
    EVP_MD_CTX* mdctx = NULL;
    unsigned char* digest = NULL;
    unsigned int digestLen = 0;
    int result = 0;

    if (msg == NULL || msgLen == 0 || sig == NULL || rw == NULL || md == NULL)
        goto err;

    if (rw->N == NULL)
        goto err;

    if ((mdctx = EVP_MD_CTX_create()) == NULL)
        goto err;

    if (1 != EVP_DigestInit_ex(mdctx, md, NULL))
        goto err;

    int size_to_alloc = EVP_MD_size(md);
    if (size_to_alloc <= 0)
        goto err;

    if ((digest = (unsigned char*)malloc(size_to_alloc)) == NULL)
        goto err;

    if (1 != EVP_DigestUpdate(mdctx, msg, msgLen))
        goto err;

    if (1 != EVP_DigestFinal_ex(mdctx, digest, &digestLen))
        goto err;

    result = RwPssrVerifyHash(digest, sig, sig_len, rw, md);

err:
    if (mdctx != NULL)
        EVP_MD_CTX_destroy(mdctx);
    if (digest != NULL)
        free(digest);

    return result;
}