int create_hash(char *plaintext, char *digest) {
    char digest_buff[3];
    DWORD buf_size = SHA1_HASH_LEN;
    HCRYPTPROV prov;
    HCRYPTHASH hash;
    BYTE rgbHash[SHA1_HASH_LEN];
    CHAR rgbDigits[] = "0123456789abcdef";
    int i;

    if(!CryptAcquireContext(&prov, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT)) {
        if(DEBUG) {
            printf("CryptAcquireContext failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    if(!CryptCreateHash(prov, CALG_SHA, NULL, NULL, &hash)) {
        if(DEBUG) {
            printf("CryptCreateHash failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    if(!CryptHashData(hash, (BYTE *)plaintext, sizeof(hash), NULL)) {
        if(DEBUG) {
            printf("CryptHashData failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    if(!CryptGetHashParam(hash, HP_HASHVAL, rgbHash, &buf_size, NULL)) {
        if(DEBUG) {
            printf("CryptGetHashParam failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    for(i=0; i < buf_size; i++) {
        sprintf(digest_buff, "%c%c", rgbDigits[rgbHash[i] >> 4], rgbDigits[rgbHash[i] & 0xf]);
        strcat(digest, digest_buff);
    }

    if(!CryptDestroyHash(hash)) {
        if(DEBUG) {
            printf("CryptDestroyHash failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    if(!CryptReleaseContext(prov, NULL)) {
        if(DEBUG) {
            printf("CryptReleaseContext failed: %d\n", GetLastError());
        }
        return SHA1_FAILED;
    }

    if(DEBUG) {
        printf("digest: %s\n", digest);
    }

    return 0;
}