instalar - Contraseña para la función de tecla compatible con los comandos de OpenSSL?

openssl pkcs12

Question

Por ejemplo, el comando:

openssl enc -aes-256-cbc -a -in test.txt -k pinkrhino -nosalt -p -out openssl_output.txt

produce algo como:

key = 33D890D33F91D52FC9B405A0DDA65336C3C4B557A3D79FE69AB674BE82C5C3D2
iv  = 677C95C475C0E057B739750748608A49

¿Cómo se genera esa clave? (El código C como respuesta sería demasiado impresionante como para preguntar :)) Además, ¿cómo se genera el iv?

Parece una especie de maleficio para mí.

Answer 1

Si alguien está buscando implementar lo mismo en SWIFT, convertí el EVP_BytesToKey la EVP_BytesToKey

 /*
 - parameter keyLen: keyLen
 - parameter ivLen:  ivLen
 - parameter digest: digest e.g "md5" or "sha1"
 - parameter salt:   salt
 - parameter data:   data
 - parameter count:  count

 - returns: key and IV respectively
 */
open static func evpBytesToKey(_ keyLen:Int, ivLen:Int, digest:String, salt:[UInt8], data:Data, count:Int)-> [[UInt8]] {
    let saltData = Data(bytes: UnsafePointer<UInt8>(salt), count: Int(salt.count))
    var both = [[UInt8]](repeating: [UInt8](), count: 2)
    var key = [UInt8](repeating: 0,count: keyLen)
    var key_ix = 0
    var iv = [UInt8](repeating: 0,count: ivLen)
    var iv_ix = 0

    var nkey = keyLen;
    var niv = ivLen;

    var i = 0
    var addmd = 0
    var md:Data = Data()
    var md_buf:[UInt8]

    while true {

        addmd = addmd + 1
        md.append(data)
        md.append(saltData)

        if(digest=="md5"){
            md = NSData(data:md.md5()) as Data
        }else if (digest == "sha1"){
            md = NSData(data:md.sha1()) as Data
        }

        for _ in 1...(count-1){

            if(digest=="md5"){
                md = NSData(data:md.md5()) as Data
            }else if (digest == "sha1"){
                md = NSData(data:md.sha1()) as Data
            }
        }
        md_buf = Array (UnsafeBufferPointer(start: md.bytes, count: md.count))
        //            md_buf = Array(UnsafeBufferPointer(start: md.bytes.bindMemory(to: UInt8.self, capacity: md.count), count: md.length))
        i = 0
        if (nkey > 0) {
            while(true) {
                if (nkey == 0){
                    break
                }
                if (i == md.count){
                    break
                }
                key[key_ix] = md_buf[i];
                key_ix = key_ix + 1
                nkey = nkey - 1
                i = i + 1
            }
        }
        if (niv > 0 && i != md_buf.count) {
            while(true) {
                if (niv == 0){
                    break
                }
                if (i == md_buf.count){
                    break
                }
                iv[iv_ix] = md_buf[i]
                iv_ix = iv_ix + 1
                niv = niv - 1
                i = i + 1
            }
        }
        if (nkey == 0 && niv == 0) {
            break
        }

    }
    both[0] = key
    both[1] = iv

    return both

}

Yo uso CryptoSwift para el hash. Esta es una forma mucho más limpia ya que las manzanas no recomiendan OpenSSL en iOS

ACTUALIZACIÓN: Swift 3

Answer 2

Aquí hay una versión para mbedTLS / Polar SSL - probado y en funcionamiento.

typedef int bool;
#define false 0
#define true (!false)
//------------------------------------------------------------------------------
static bool EVP_BytesToKey( const unsigned int nDesiredKeyLen, const unsigned char* salt,
                            const unsigned char* password, const unsigned int nPwdLen,
                            unsigned char* pOutKey, unsigned char* pOutIV )
{
    // This is a re-implemntation of openssl''s password to key & IV routine for mbedtls.
    //  (See openssl apps/enc.c and /crypto/evp/evp_key.c) It is not any kind of
    //  standard (e.g. PBKDF2), and it only uses an interation count of 1, so it''s
    //  pretty crappy. MD5 is used as the digest in Openssl 1.0.2, 1.1 and late
    //  use SHA256. Since this is for embedded system, I figure you know what you''ve
    //  got, so I made it compile-time configurable.
    //
    //  The signature has been re-jiggered to make it less general. 
    //
    //  See: https://wiki.openssl.org/index.php/Manual:EVP_BytesToKey(3)
    //  And: https://www.cryptopp.com/wiki/OPENSSL_EVP_BytesToKey

#define IV_BYTE_COUNT     16

#if BTK_USE_MD5
#  define DIGEST_BYTE_COUNT 16 // MD5
#else
#  define DIGEST_BYTE_COUNT 32 // SHA
#endif

    bool bRet;
    unsigned char md_buf[ DIGEST_BYTE_COUNT ];
    mbedtls_md_context_t md_ctx;
    bool bAddLastMD = false;
    unsigned int nKeyToGo = nDesiredKeyLen;  // 32, typical
    unsigned int nIVToGo  = IV_BYTE_COUNT;

    mbedtls_md_init( &md_ctx );

#if BTK_USE_MD5
    int rc = mbedtls_md_setup( &md_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_MD5  ), 0 ); 
#else
    int rc = mbedtls_md_setup( &md_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 ); 
#endif

    if (rc != 0 )
    {
        fprintf( stderr, "mbedutils_md_setup() failed -0x%04x/n", -rc );
        bRet = false;
        goto exit;
    }

    while( 1 )
    {
        mbedtls_md_starts( &md_ctx );  // start digest

        if ( bAddLastMD == false )  // first time
        {
            bAddLastMD = true;      // do it next time
        }
        else
        {
            mbedtls_md_update( &md_ctx, &md_buf[0], DIGEST_BYTE_COUNT );
        }

        mbedtls_md_update( &md_ctx, &password[0], nPwdLen );
        mbedtls_md_update( &md_ctx, &salt[0], 8 );
        mbedtls_md_finish( &md_ctx, &md_buf[0] );

        //
        // Iteration loop here in original removed as unused by "openssl enc"
        //

        // Following code treats the output key and iv as one long, concatentated buffer
        //   and smears as much digest across it as is available. If not enough, it takes the
        //   big, enclosing loop, makes more digest, and continues where it left off on
        //   the last iteration.
        unsigned int ii = 0;  // index into mb_buf

        if ( nKeyToGo != 0 )    // still have key to fill in?
        {
            while( 1 )
            {
                if ( nKeyToGo == 0 )               // key part is full/done
                    break;
                if ( ii == DIGEST_BYTE_COUNT )     // ran out of digest, so loop
                    break;

                *pOutKey++ = md_buf[ ii ];         // stick byte in output key
                nKeyToGo--;
                ii++;
            }
        }

        if ( nIVToGo != 0                    // still have fill up IV
             &&                              // and
             ii != DIGEST_BYTE_COUNT         // have some digest available
           )
        {
            while( 1 )
            {
                if ( nIVToGo == 0 )              // iv is full/done
                    break;
                if ( ii == DIGEST_BYTE_COUNT )   // ran out of digest, so loop
                    break;
                *pOutIV++ = md_buf[ ii ];        // stick byte in output IV
                nIVToGo--;
                ii++;
            }
        }

        if ( nKeyToGo == 0  && nIVToGo == 0 )    // output full, break main loop and exit
            break;
    } // outermost while loop

    bRet = true;

  exit:
    mbedtls_md_free( &md_ctx );
    return bRet;
}

Answer 3

OpenSSL usa la función EVP_BytesToKey . Puede encontrar la llamada en apps/enc.c La utilidad enc utilizaba el resumen de MD5 de forma predeterminada en el Algoritmo de derivación de clave (KDF) si no especificaba un resumen diferente con el argumento -md . Ahora usa SHA-256 de forma predeterminada. Aquí hay un ejemplo de trabajo usando MD5:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>

int main(int argc, char *argv[])
{
    const EVP_CIPHER *cipher;
    const EVP_MD *dgst = NULL;
    unsigned char key[EVP_MAX_KEY_LENGTH], iv[EVP_MAX_IV_LENGTH];
    const char *password = "password";
    const unsigned char *salt = NULL;
    int i;

    OpenSSL_add_all_algorithms();

    cipher = EVP_get_cipherbyname("aes-256-cbc");
    if(!cipher) { fprintf(stderr, "no such cipher/n"); return 1; }

    dgst=EVP_get_digestbyname("md5");
    if(!dgst) { fprintf(stderr, "no such digest/n"); return 1; }

    if(!EVP_BytesToKey(cipher, dgst, salt,
        (unsigned char *) password,
        strlen(password), 1, key, iv))
    {
        fprintf(stderr, "EVP_BytesToKey failed/n");
        return 1;
    }

    printf("Key: "); for(i=0; i<cipher->key_len; ++i) { printf("%02x", key[i]); } printf("/n");
    printf("IV: "); for(i=0; i<cipher->iv_len; ++i) { printf("%02x", iv[i]); } printf("/n");

    return 0;
}

Ejemplo de uso:

gcc b2k.c -o b2k -lcrypto -g
./b2k
Key: 5f4dcc3b5aa765d61d8327deb882cf992b95990a9151374abd8ff8c5a7a0fe08
IV: b7b4372cdfbcb3d16a2631b59b509e94

Que genera la misma clave que esta línea de comando de OpenSSL:

openssl enc -aes-256-cbc -k password -nosalt -p < /dev/null
key=5F4DCC3B5AA765D61D8327DEB882CF992B95990A9151374ABD8FF8C5A7A0FE08
iv =B7B4372CDFBCB3D16A2631B59B509E94

OpenSSL 1.1.0c cambió el algoritmo de resumen utilizado en algunos componentes internos. Anteriormente, se usaba MD5 y 1.1.0 cambiaba a SHA256. Tenga cuidado de que el cambio no le afecte tanto en EVP_BytesToKey como en comandos como openssl enc .