Did you end up finding a solution to this problem? I'm looking at needing
the EVP_BytesToKey function as well, but really don't want to include an
openssl dependency if I'm already using crypto++.
On Sunday, 23 October 2011 21:26:05 UTC+10, asoko wrote:
>
> I was able to advance a little bit using OpenSSL library :
>
>
> #include <openssl/evp.h>
>
> std::string pass_phrase,file_in, file_out;
>
> unsigned char key_str[32];
> unsigned char iv[16];
> EVP_BytesToKey(EVP_aes_256_cbc(),
> EVP_md5(),
> NULL,
> (unsigned char*)pass_phrase.c_str(),
> pass_phrase.size(),
> 1,
> key_str,
> iv);
>
> CryptoPP::SecByteBlock key(key_str,32);
>
> CryptoPP::CBC_Mode<CryptoPP::AES>::Decryption cfbDecryption(key,
> key.m_size,
> iv);
>
> CryptoPP::FileSource f(file_in.c_str(),
> true,
> new CryptoPP::StreamTransformationFilter(cfbDecryption,
> new CryptoPP::FileSink(file_out.c_str())));
>
> So I guess need to translate EVP_BytesToKey into Crypto++ lingo.
>
>
> int EVP_BytesToKey(const EVP_CIPHER *type, const EVP_MD *md,
> const unsigned char *salt, const unsigned char *data, int datal,
> int count, unsigned char *key, unsigned char *iv)
> {
> EVP_MD_CTX c;
> unsigned char md_buf[EVP_MAX_MD_SIZE];
> int niv,nkey,addmd=0;
> unsigned int mds=0,i;
>
> nkey=type->key_len;
> niv=type->iv_len;
> OPENSSL_assert(nkey <= EVP_MAX_KEY_LENGTH);
> OPENSSL_assert(niv <= EVP_MAX_IV_LENGTH);
>
> if (data == NULL) return(nkey);
>
> EVP_MD_CTX_init(&c);
> for (;;)
> {
> if (!EVP_DigestInit_ex(&c,md, NULL))
> return 0;
> if (addmd++)
> EVP_DigestUpdate(&c,&(md_buf[0]),mds);
> EVP_DigestUpdate(&c,data,datal);
> if (salt != NULL)
> EVP_DigestUpdate(&c,salt,PKCS5_SALT_LEN);
> EVP_DigestFinal_ex(&c,&(md_buf[0]),&mds);
>
> for (i=1; i<(unsigned int)count; i++)
> {
> EVP_DigestInit_ex(&c,md, NULL);
> EVP_DigestUpdate(&c,&(md_buf[0]),mds);
> EVP_DigestFinal_ex(&c,&(md_buf[0]),&mds);
> }
> i=0;
> if (nkey)
> {
> for (;;)
> {
> if (nkey == 0) break;
> if (i == mds) break;
> if (key != NULL)
> *(key++)=md_buf[i];
> nkey--;
> i++;
> }
> }
> if (niv && (i != mds))
> {
> for (;;)
> {
> if (niv == 0) break;
> if (i == mds) break;
> if (iv != NULL)
> *(iv++)=md_buf[i];
> niv--;
> i++;
> }
> }
> if ((nkey == 0) && (niv == 0)) break;
> }
> EVP_MD_CTX_cleanup(&c);
> OPENSSL_cleanse(&(md_buf[0]),EVP_MAX_MD_SIZE);
> return(type->key_len);
> }
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