Программа на C / C ++ с тем же выводом, что и / usr / bin / openssl

Question

Моя цель - создать программу на C / C ++, которая шифрует / дешифрует данные (в файл), которая совместима со стандартной двоичной утилитой OpenSSL. В идеале администратор мог бы зашифровать текст с помощью команды "/usr/bin/openssl enc -aes-128-cbc -in input.txt -k password -a " ... и тогда программа на C / C ++ сможет расшифровать хеш base64.

К сожалению, примеров шифрования AES с помощью OpenSSL очень мало, и неясно, какими являются параметры по умолчанию при использовании утилиты / usr / bin / openssl. Единственный пример шифрования aes, который я нашел, был этот (http://saju.net.in/blog/?p=36), но я не смог заставить его выдать тот же вывод, что и /usr/bin/openssl.

Есть какие-нибудь подсказки? Стоит ли искать исходный код утилиты openssl?

Спасибо!

Answer 1

К сожалению, примеров шифрования AES с использованием OpenSSL

очень мало.

Возможно, вам следует сначала изучить что-то вроде примера OpenSSL EVP Symmetric Encryption and Decryption . Его легче переварить, и некоторые технические изменения выполняются, чтобы обеспечить его правильность, чем многие плохие примеры, которые я видел.

не ясно, какие параметры по умолчанию используются при использовании / usr / bin / openssl

Вы найдете это в enc.c. Я полагаю, что все подкоманды (такие как enc, dec, s_client и s_server) имеют сопутствующий исходный файл. Вы можете найти его в папке apps: openssl-1.0.1e\apps\enc.c. Если вы хотите увидеть, как пароль используется, следуйте инструкциям EVP_read_pw_string.

int MAIN(int argc, char **argv)
{
    static const char magic[]="Salted__";
    char mbuf[sizeof magic-1];
    char *strbuf=NULL;
    unsigned char *buff=NULL,*bufsize=NULL;
    int bsize=BSIZE,verbose=0;
    int ret=1,inl;
    int nopad = 0;
    unsigned char key[EVP_MAX_KEY_LENGTH],iv[EVP_MAX_IV_LENGTH];
    unsigned char salt[PKCS5_SALT_LEN];
    char *str=NULL, *passarg = NULL, *pass = NULL;
    char *hkey=NULL,*hiv=NULL,*hsalt = NULL;
    char *md=NULL;
    int enc=1,printkey=0,i,base64=0;
#ifdef ZLIB
    int do_zlib=0;
    BIO *bzl = NULL;
#endif
    int debug=0,olb64=0,nosalt=0;
    const EVP_CIPHER *cipher=NULL,*c;
    EVP_CIPHER_CTX *ctx = NULL;
    char *inf=NULL,*outf=NULL;
    BIO *in=NULL,*out=NULL,*b64=NULL,*benc=NULL,*rbio=NULL,*wbio=NULL;
#define PROG_NAME_SIZE  39
    char pname[PROG_NAME_SIZE+1];
#ifndef OPENSSL_NO_ENGINE
    char *engine = NULL;
#endif
    const EVP_MD *dgst=NULL;
    int non_fips_allow = 0;

    apps_startup();

    if (bio_err == NULL)
        if ((bio_err=BIO_new(BIO_s_file())) != NULL)
            BIO_set_fp(bio_err,stderr,BIO_NOCLOSE|BIO_FP_TEXT);

    if (!load_config(bio_err, NULL))
        goto end;

    /* first check the program name */
    program_name(argv[0],pname,sizeof pname);
    if (strcmp(pname,"base64") == 0)
        base64=1;
#ifdef ZLIB
    if (strcmp(pname,"zlib") == 0)
        do_zlib=1;
#endif

    cipher=EVP_get_cipherbyname(pname);
#ifdef ZLIB
    if (!do_zlib && !base64 && (cipher == NULL)
        && (strcmp(pname,"enc") != 0))
#else
        if (!base64 && (cipher == NULL) && (strcmp(pname,"enc") != 0))
#endif
        {
            BIO_printf(bio_err,"%s is an unknown cipher\n",pname);
            goto bad;
        }

    argc--;
    argv++;
    while (argc >= 1)
    {
        if  (strcmp(*argv,"-e") == 0)
            enc=1;
        else if (strcmp(*argv,"-in") == 0)
        {
            if (--argc < 1) goto bad;
            inf= *(++argv);
        }
        else if (strcmp(*argv,"-out") == 0)
        {
            if (--argc < 1) goto bad;
            outf= *(++argv);
        }
        else if (strcmp(*argv,"-pass") == 0)
        {
            if (--argc < 1) goto bad;
            passarg= *(++argv);
        }
#ifndef OPENSSL_NO_ENGINE
        else if (strcmp(*argv,"-engine") == 0)
        {
            if (--argc < 1) goto bad;
            engine= *(++argv);
        }
#endif
        else if (strcmp(*argv,"-d") == 0)
            enc=0;
        else if (strcmp(*argv,"-p") == 0)
            printkey=1;
        else if (strcmp(*argv,"-v") == 0)
            verbose=1;
        else if (strcmp(*argv,"-nopad") == 0)
            nopad=1;
        else if (strcmp(*argv,"-salt") == 0)
            nosalt=0;
        else if (strcmp(*argv,"-nosalt") == 0)
            nosalt=1;
        else if (strcmp(*argv,"-debug") == 0)
            debug=1;
        else if (strcmp(*argv,"-P") == 0)
            printkey=2;
        else if (strcmp(*argv,"-A") == 0)
            olb64=1;
        else if (strcmp(*argv,"-a") == 0)
            base64=1;
        else if (strcmp(*argv,"-base64") == 0)
            base64=1;
#ifdef ZLIB
        else if (strcmp(*argv,"-z") == 0)
            do_zlib=1;
#endif
        else if (strcmp(*argv,"-bufsize") == 0)
        {
            if (--argc < 1) goto bad;
            bufsize=(unsigned char *)*(++argv);
        }
        else if (strcmp(*argv,"-k") == 0)
        {
            if (--argc < 1) goto bad;
            str= *(++argv);
        }
        else if (strcmp(*argv,"-kfile") == 0)
        {
            static char buf[128];
            FILE *infile;
            char *file;

            if (--argc < 1) goto bad;
            file= *(++argv);
            infile=fopen(file,"r");
            if (infile == NULL)
            {
                BIO_printf(bio_err,"unable to read key from '%s'\n",
                           file);
                goto bad;
            }
            buf[0]='\0';
            if (!fgets(buf,sizeof buf,infile))
            {
                BIO_printf(bio_err,"unable to read key from '%s'\n",
                           file);
                goto bad;
            }
            fclose(infile);
            i=strlen(buf);
            if ((i > 0) &&
                ((buf[i-1] == '\n') || (buf[i-1] == '\r')))
                buf[--i]='\0';
            if ((i > 0) &&
                ((buf[i-1] == '\n') || (buf[i-1] == '\r')))
                buf[--i]='\0';
            if (i < 1)
            {
                BIO_printf(bio_err,"zero length password\n");
                goto bad;
            }
            str=buf;
        }
        else if (strcmp(*argv,"-K") == 0)
        {
            if (--argc < 1) goto bad;
            hkey= *(++argv);
        }
        else if (strcmp(*argv,"-S") == 0)
        {
            if (--argc < 1) goto bad;
            hsalt= *(++argv);
        }
        else if (strcmp(*argv,"-iv") == 0)
        {
            if (--argc < 1) goto bad;
            hiv= *(++argv);
        }
        else if (strcmp(*argv,"-md") == 0)
        {
            if (--argc < 1) goto bad;
            md= *(++argv);
        }
        else if (strcmp(*argv,"-non-fips-allow") == 0)
            non_fips_allow = 1;
        else if ((argv[0][0] == '-') &&
                 ((c=EVP_get_cipherbyname(&(argv[0][1]))) != NULL))
        {
            cipher=c;
        }
        else if (strcmp(*argv,"-none") == 0)
            cipher=NULL;
        else
        {
            BIO_printf(bio_err,"unknown option '%s'\n",*argv);
        bad:
            BIO_printf(bio_err,"options are\n");
            BIO_printf(bio_err,"%-14s input file\n","-in <file>");
            BIO_printf(bio_err,"%-14s output file\n","-out <file>");
            BIO_printf(bio_err,"%-14s pass phrase source\n","-pass <arg>");
            BIO_printf(bio_err,"%-14s encrypt\n","-e");
            BIO_printf(bio_err,"%-14s decrypt\n","-d");
            BIO_printf(bio_err,"%-14s base64 encode/decode, depending on encryption flag\n","-a/-base64");
            BIO_printf(bio_err,"%-14s passphrase is the next argument\n","-k");
            BIO_printf(bio_err,"%-14s passphrase is the first line of the file argument\n","-kfile");
            BIO_printf(bio_err,"%-14s the next argument is the md to use to create a key\n","-md");
            BIO_printf(bio_err,"%-14s   from a passphrase.  One of md2, md5, sha or sha1\n","");
            BIO_printf(bio_err,"%-14s salt in hex is the next argument\n","-S");
            BIO_printf(bio_err,"%-14s key/iv in hex is the next argument\n","-K/-iv");
            BIO_printf(bio_err,"%-14s print the iv/key (then exit if -P)\n","-[pP]");
            BIO_printf(bio_err,"%-14s buffer size\n","-bufsize <n>");
            BIO_printf(bio_err,"%-14s disable standard block padding\n","-nopad");
#ifndef OPENSSL_NO_ENGINE
            BIO_printf(bio_err,"%-14s use engine e, possibly a hardware device.\n","-engine e");
#endif

            BIO_printf(bio_err,"Cipher Types\n");
            OBJ_NAME_do_all_sorted(OBJ_NAME_TYPE_CIPHER_METH,
                                   show_ciphers,
                                   bio_err);
            BIO_printf(bio_err,"\n");

            goto end;
        }
        argc--;
        argv++;
    }

#ifndef OPENSSL_NO_ENGINE
    setup_engine(bio_err, engine, 0);
#endif

    if (md && (dgst=EVP_get_digestbyname(md)) == NULL)
    {
        BIO_printf(bio_err,"%s is an unsupported message digest type\n",md);
        goto end;
    }

    if (dgst == NULL)
    {
        dgst = EVP_md5();
    }

    if (bufsize != NULL)
    {
        unsigned long n;

        for (n=0; *bufsize; bufsize++)
        {
            i= *bufsize;
            if ((i <= '9') && (i >= '0'))
                n=n*10+i-'0';
            else if (i == 'k')
            {
                n*=1024;
                bufsize++;
                break;
            }
        }
        if (*bufsize != '\0')
        {
            BIO_printf(bio_err,"invalid 'bufsize' specified.\n");
            goto end;
        }

        /* It must be large enough for a base64 encoded line */
        if (base64 && n < 80) n=80;

        bsize=(int)n;
        if (verbose) BIO_printf(bio_err,"bufsize=%d\n",bsize);
    }

    strbuf=OPENSSL_malloc(SIZE);
    buff=(unsigned char *)OPENSSL_malloc(EVP_ENCODE_LENGTH(bsize));
    if ((buff == NULL) || (strbuf == NULL))
    {
        BIO_printf(bio_err,"OPENSSL_malloc failure %ld\n",(long)EVP_ENCODE_LENGTH(bsize));
        goto end;
    }

    in=BIO_new(BIO_s_file());
    out=BIO_new(BIO_s_file());
    if ((in == NULL) || (out == NULL))
    {
        ERR_print_errors(bio_err);
        goto end;
    }
    if (debug)
    {
        BIO_set_callback(in,BIO_debug_callback);
        BIO_set_callback(out,BIO_debug_callback);
        BIO_set_callback_arg(in,(char *)bio_err);
        BIO_set_callback_arg(out,(char *)bio_err);
    }

    if (inf == NULL)
    {
#ifndef OPENSSL_NO_SETVBUF_IONBF
        if (bufsize != NULL)
            setvbuf(stdin, (char *)NULL, _IONBF, 0);
#endif /* ndef OPENSSL_NO_SETVBUF_IONBF */
        BIO_set_fp(in,stdin,BIO_NOCLOSE);
    }
    else
    {
        if (BIO_read_filename(in,inf) <= 0)
        {
            perror(inf);
            goto end;
        }
    }

    if(!str && passarg) {
        if(!app_passwd(bio_err, passarg, NULL, &pass, NULL)) {
            BIO_printf(bio_err, "Error getting password\n");
            goto end;
        }
        str = pass;
    }

    if ((str == NULL) && (cipher != NULL) && (hkey == NULL))
    {
        for (;;)
        {
            char buf[200];

            BIO_snprintf(buf,sizeof buf,"enter %s %s password:",
                         OBJ_nid2ln(EVP_CIPHER_nid(cipher)),
                         (enc)?"encryption":"decryption");
            strbuf[0]='\0';
            i=EVP_read_pw_string((char *)strbuf,SIZE,buf,enc);
            if (i == 0)
            {
                if (strbuf[0] == '\0')
                {
                    ret=1;
                    goto end;
                }
                str=strbuf;
                break;
            }
            if (i < 0)
            {
                BIO_printf(bio_err,"bad password read\n");
                goto end;
            }
        }
    }


    if (outf == NULL)
    {
        BIO_set_fp(out,stdout,BIO_NOCLOSE);
#ifndef OPENSSL_NO_SETVBUF_IONBF
        if (bufsize != NULL)
            setvbuf(stdout, (char *)NULL, _IONBF, 0);
#endif /* ndef OPENSSL_NO_SETVBUF_IONBF */
#ifdef OPENSSL_SYS_VMS
        {
            BIO *tmpbio = BIO_new(BIO_f_linebuffer());
            out = BIO_push(tmpbio, out);
        }
#endif
    }
    else
    {
        if (BIO_write_filename(out,outf) <= 0)
        {
            perror(outf);
            goto end;
        }
    }

    rbio=in;
    wbio=out;

#ifdef ZLIB

    if (do_zlib)
    {
        if ((bzl=BIO_new(BIO_f_zlib())) == NULL)
            goto end;
        if (enc)
            wbio=BIO_push(bzl,wbio);
        else
            rbio=BIO_push(bzl,rbio);
    }
#endif

    if (base64)
    {
        if ((b64=BIO_new(BIO_f_base64())) == NULL)
            goto end;
        if (debug)
        {
            BIO_set_callback(b64,BIO_debug_callback);
            BIO_set_callback_arg(b64,(char *)bio_err);
        }
        if (olb64)
            BIO_set_flags(b64,BIO_FLAGS_BASE64_NO_NL);
        if (enc)
            wbio=BIO_push(b64,wbio);
        else
            rbio=BIO_push(b64,rbio);
    }

    if (cipher != NULL)
    {
        /* Note that str is NULL if a key was passed on the command
         * line, so we get no salt in that case. Is this a bug?
         */
        if (str != NULL)
        {
            /* Salt handling: if encrypting generate a salt and
             * write to output BIO. If decrypting read salt from
             * input BIO.
             */
            unsigned char *sptr;
            if(nosalt) sptr = NULL;
            else {
                if(enc) {
                    if(hsalt) {
                        if(!set_hex(hsalt,salt,sizeof salt)) {
                            BIO_printf(bio_err,
                                       "invalid hex salt value\n");
                            goto end;
                        }
                    } else if (RAND_pseudo_bytes(salt, sizeof salt) < 0)
                        goto end;
                    /* If -P option then don't bother writing */
                    if((printkey != 2)
                       && (BIO_write(wbio,magic,
                                     sizeof magic-1) != sizeof magic-1
                           || BIO_write(wbio,
                                        (char *)salt,
                                        sizeof salt) != sizeof salt)) {
                               BIO_printf(bio_err,"error writing output file\n");
                               goto end;
                           }
                } else if(BIO_read(rbio,mbuf,sizeof mbuf) != sizeof mbuf
                          || BIO_read(rbio,
                                      (unsigned char *)salt,
                                      sizeof salt) != sizeof salt) {
                              BIO_printf(bio_err,"error reading input file\n");
                              goto end;
                          } else if(memcmp(mbuf,magic,sizeof magic-1)) {
                              BIO_printf(bio_err,"bad magic number\n");
                              goto end;
                          }

                sptr = salt;
            }

            EVP_BytesToKey(cipher,dgst,sptr,
                           (unsigned char *)str,
                           strlen(str),1,key,iv);
            /* zero the complete buffer or the string
             * passed from the command line
             * bug picked up by
             * Larry J. Hughes Jr. <hughes@indiana.edu> */
            if (str == strbuf)
                OPENSSL_cleanse(str,SIZE);
            else
                OPENSSL_cleanse(str,strlen(str));
        }
        if ((hiv != NULL) && !set_hex(hiv,iv,sizeof iv))
        {
            BIO_printf(bio_err,"invalid hex iv value\n");
            goto end;
        }
        if ((hiv == NULL) && (str == NULL)
            && EVP_CIPHER_iv_length(cipher) != 0)
        {
            /* No IV was explicitly set and no IV was generated
             * during EVP_BytesToKey. Hence the IV is undefined,
             * making correct decryption impossible. */
            BIO_printf(bio_err, "iv undefined\n");
            goto end;
        }
        if ((hkey != NULL) && !set_hex(hkey,key,sizeof key))
        {
            BIO_printf(bio_err,"invalid hex key value\n");
            goto end;
        }

        if ((benc=BIO_new(BIO_f_cipher())) == NULL)
            goto end;

        /* Since we may be changing parameters work on the encryption
         * context rather than calling BIO_set_cipher().
         */

        BIO_get_cipher_ctx(benc, &ctx);

        if (non_fips_allow)
            EVP_CIPHER_CTX_set_flags(ctx,
                                     EVP_CIPH_FLAG_NON_FIPS_ALLOW);

        if (!EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, enc))
        {
            BIO_printf(bio_err, "Error setting cipher %s\n",
                       EVP_CIPHER_name(cipher));
            ERR_print_errors(bio_err);
            goto end;
        }

        if (nopad)
            EVP_CIPHER_CTX_set_padding(ctx, 0);

        if (!EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, enc))
        {
            BIO_printf(bio_err, "Error setting cipher %s\n",
                       EVP_CIPHER_name(cipher));
            ERR_print_errors(bio_err);
            goto end;
        }

        if (debug)
        {
            BIO_set_callback(benc,BIO_debug_callback);
            BIO_set_callback_arg(benc,(char *)bio_err);
        }

        if (printkey)
        {
            if (!nosalt)
            {
                printf("salt=");
                for (i=0; i<(int)sizeof(salt); i++)
                    printf("%02X",salt[i]);
                printf("\n");
            }
            if (cipher->key_len > 0)
            {
                printf("key=");
                for (i=0; i<cipher->key_len; i++)
                    printf("%02X",key[i]);
                printf("\n");
            }
            if (cipher->iv_len > 0)
            {
                printf("iv =");
                for (i=0; i<cipher->iv_len; i++)
                    printf("%02X",iv[i]);
                printf("\n");
            }
            if (printkey == 2)
            {
                ret=0;
                goto end;
            }
        }
    }

    /* Only encrypt/decrypt as we write the file */
    if (benc != NULL)
        wbio=BIO_push(benc,wbio);

    for (;;)
    {
        inl=BIO_read(rbio,(char *)buff,bsize);
        if (inl <= 0) break;
        if (BIO_write(wbio,(char *)buff,inl) != inl)
        {
            BIO_printf(bio_err,"error writing output file\n");
            goto end;
        }
    }
    if (!BIO_flush(wbio))
    {
        BIO_printf(bio_err,"bad decrypt\n");
        goto end;
    }

    ret=0;
    if (verbose)
    {
        BIO_printf(bio_err,"bytes read   :%8ld\n",BIO_number_read(in));
        BIO_printf(bio_err,"bytes written:%8ld\n",BIO_number_written(out));
    }
end:
    ERR_print_errors(bio_err);
    if (strbuf != NULL) OPENSSL_free(strbuf);
    if (buff != NULL) OPENSSL_free(buff);
    if (in != NULL) BIO_free(in);
    if (out != NULL) BIO_free_all(out);
    if (benc != NULL) BIO_free(benc);
    if (b64 != NULL) BIO_free(b64);
#ifdef ZLIB
    if (bzl != NULL) BIO_free(bzl);
#endif
    if(pass) OPENSSL_free(pass);
    apps_shutdown();
    OPENSSL_EXIT(ret);
}