On Sun, May 1, 2011 at 1:48 AM, derleader mail <derlea...@abv.bg> wrote:
>
> Hi,
>
> The encrypted output is not a NULL terminated string so strlen will not
> work.
>
> >> EVP_DecryptUpdate(&ctx, (unsigned char *)plaintextz, &out_len, (unsigned
> char *)ciphertext, strlen(ciphertext));
>
> Use the length output from the encryption part.
>
> Thank you very much for the reply. The problem is that the encryption and
> decryption must be on separate machines. I need a way to take the size of
> the encrypted message using language function like strlen(). Is there
> other solution?
>
Hi,
What protocol are you using?
If you cannot send the "length" of the encrypted data, then you cannot
decrypt it properly.
>
> Regards
>
> - re
>
> On Sun, May 1, 2011 at 12:27 AM, derleader mail <derlea...@abv.bg> wrote:
>
>> Hi,
>> I'm trying to code a C program that can convert very big number of
>> characters. The problem is that there is an error in decryption.
>>
>> This is the code:
>>
>> //gcc test_Blowfish.c -L/usr/local/ssl/lib/ -lssl -lcrypto -Wall
>>
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <strings.h>
>> #include <openssl/blowfish.h>
>> #include <openssl/evp.h>
>>
>> int main(void) {
>>
>> char plaintext[1024] = "{aaX{aaX57 : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa57
>> : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa{aaX57
>> : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa";
>> char plaintextz[1024];
>> char ciphertext[1024]= {0,};
>> char mykey[EVP_MAX_KEY_LENGTH] = "blowfish_key";
>> char iv[EVP_MAX_IV_LENGTH] = "blowfish";
>> int tmp_len = 0, in_len, out_len=0;
>> EVP_CIPHER_CTX ctx;
>>
>> //memset(mykey,0,sizeof(mykey));
>> //memset(iv,0,sizeof(iv));
>>
>>
>>
>> printf("No encrypt: %s\n", plaintext);
>> printf("No encrypt size: %d\n", strlen(plaintext));
>>
>> //Encrypt
>> EVP_EncryptInit(&ctx, EVP_bf_cfb(), (unsigned char *)mykey, (unsigned
>> char *)iv);
>> EVP_EncryptUpdate(&ctx, (unsigned char *)ciphertext, &out_len,
>> (unsigned char *)plaintext, strlen(plaintext)); //Block through the mem
>> to be encrypted
>> tmp_len += out_len;
>> EVP_EncryptFinal(&ctx, (unsigned char *) &ciphertext[out_len],
>> &out_len); //Finish any remaining encryption and throw a pad on
>> tmp_len += out_len;
>> printf("Encrypted: %s\n", ciphertext);
>> printf("Encrypted size: %d\n", tmp_len);
>>
>> //Reset memory for Decryption
>> // memset(plaintext,0,sizeof(plaintext));
>> in_len = tmp_len;
>> out_len = tmp_len = 0;
>>
>> //decrypt
>> EVP_DecryptInit(&ctx, EVP_bf_cfb(), (unsigned char *)mykey, (unsigned
>> char *)iv);
>> EVP_DecryptUpdate(&ctx, (unsigned char *)plaintextz, &out_len,
>> (unsigned char *)ciphertext, strlen(ciphertext));
>> tmp_len += out_len;
>> EVP_DecryptFinal(&ctx, (unsigned char *)&plaintextz[out_len],
>> &out_len);
>> tmp_len += out_len;
>>
>> //Zero out the pad
>> memset(&plaintext[tmp_len],0,(int)(sizeof(plaintext)) - tmp_len);
>>
>> printf("Decrypted : %s\n", plaintextz);
>> printf("Decrypted size: %d\n", tmp_len);
>>
>> printf("Block Size: %d\n",EVP_CIPHER_CTX_block_size(&ctx));
>>
>> return 0;
>> }
>>
>>
>>
>> This is the output:
>>
>> [root@localhost test]# ./a.out
>> No encrypt: {aaX{aaX57 : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa57
>> : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa{aaX57
>> : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa
>> No encrypt size: 267
>> Encrypted: �A-�� W =?:�$�i �_�8:�F�wo#�5 � @D�mo��-I ���F�Q�J�#��F�0b�
>> ;�`� C䦱�~6�)ހ�YG �ed�Ӕ�Z%�9!mdvϋ���\���QB��}�N ����@_�W�F�e"�
>> Encrypted size: 267
>> Decrypted : {aaX{aaX57 : {223 :
>> 2323}}{}{}{}{}{}{3535:42424}242424242242424243r23r23r23r23r23r23r3r{}pppa57
>> : {223 : 2323}}{}{}{}{}{}{3535:4242
>> Decrypted size: 131
>> Block Size: 1
>>
>> As youy see the decrypted size number is less that the original.
>> Any idea where is the problem?
>>
>>
>
>
