On Fri, Apr 23, 2004, Carlos Roberto Zainos H wrote:
> Hi all!!!
>
> Thanks again for the answers.
>
> The question that I now post refers to decrypt a private key PBE (PKCS#5).
> I've working with priv/pub keys gotten from openssl, but now my C
> applications needs to work with ones generated with another application
> (commercial software). I've been discovered (with openssl help) that private
> key is in "clear" PEM format (not encrypted) and PBE (PKCS#5 v2(?))
> protected (form DER: privkey.key ). My problem is that I can't decrypt that
> key for use this in my C application. Follows my code:
>
> alg = PKCS5_pbe2_set (EVP_des_cbc(), -1, NULL, 0); /*pkcs5 v2.0 */ err =
> EVP_PBE_CipherInit (alg->algorithm, password, strlen(password),
> alg->parameter, &ctx, decripta); /*descripta is defined as 0 */ decr_buf =
> (unsigned char *) malloc (longitud + EVP_CIPHER_CTX_block_size(&ctx) + 1);
> err = EVP_CipherUpdate (&ctx, decr_buf, &bytes_decr, privkey_pointer,
> length_privkey); err = EVP_CipherFinal (&ctx, decr_buf+bytes_decr,
> &bytes_final); if ( err == 0 ) { printf("Ha ocurrido un error
> EVP_CipherFinal \n"); while ( c_error = ERR_get_error() ) fprintf(stderr,
> ERR_error_string(c_error, NULL)); exit(1); }
>
> So, err always is 0 in EVP_CipherFinal, error code returns:
> error:0606506D:digital envelope routines:EVP_DecryptFinal:wrong final block
> length
>
> I thought that the problem could be the priv key, so I generate privkeys in
> PKCS#5 and PKCS#8 with: openssl pkcs8 -inform DER -in privkey.key -topk8 -v1
> PBE_MD5_DES -outform DER -out privkeyp5.key ; and openssl pkcs8 -inform DER
> -in privkey.key -topk8 -outform DER -out privkeyp8.key
>
> And test my application again with those keys but results are the same.
>
> I don't know what is wrong ....... any suggestions or tips???
If the private key is in PEM format that PEM_read_bio_PrivateKey() will
automatically handle PKCS#8 format.
If its in DER format then d2i_PKCS8PrivateKey_bio() will handle the encrypted
form, and d2i_PKCS8_PRIV_KEY_INFO() followed by EVP_PKCS82PKEY() for the
unencrypted form.
Steve.
--
Dr Stephen N. Henson. Email, S/MIME and PGP keys: see homepage
OpenSSL project core developer and freelance consultant.
Funding needed! Details on homepage.
Homepage: http://www.drh-consultancy.demon.co.uk
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