| delite |
11-19-2008 07:07 PM |
Hi,
I'm testing with openssl. Here's what i'm using with it.
Quote:
openssl bf-cbc -in test.txt -out test2.bin -pass pass:password
openssl bf-cbc -d -in test.bin -out test2.bin.txt -pass pass:password
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Then i've taken an example of symmetrical encryption from the book 'Network Security with OpenSSL' and made it into this. I've been playing with the 'EVP_BytesToKey()' function, of which I think i've got right. It encrypts and decrypts. However when I use the actual openssl program to decrypt it states: 'bad magic number'
Also I notice that the openssl variations output is 16 bytes bigger. From looking at a hex dump I see the string 'Salted__', but thats only 8 bytes. Is the next 8 used as an iv or something? Is it converted to hex? I'm almost assuming that this is internal to a BIO (from looking within enc.c)....
Any points towards the right direction greatly appreciated...
Code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>
#define ALG EVP_des_ede3_cbc()
int do_crypt(char *fin, char *fout, int do_encrypt, char *pw)
{
static const char magic[]="Salted__";
unsigned char iv[EVP_MAX_IV_LENGTH], key[EVP_MAX_KEY_LENGTH];
EVP_BytesToKey(ALG, EVP_md5(), magic, (unsigned char*)pw, strlen(pw), 1, key, iv);
FILE *in;
in = fopen(fin, "r");
FILE *out;
out = fopen(fout, "w");
unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
int inlen, outlen;
EVP_CIPHER_CTX ctx;
EVP_CIPHER_CTX_init(&ctx);
EVP_CipherInit_ex(&ctx, EVP_bf_cbc(), NULL, NULL, NULL, do_encrypt);
EVP_CIPHER_CTX_set_key_length(&ctx, 10);
EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
for(;;)
{
inlen = fread(inbuf, 1, 1024, in);
if(inlen <= 0) break;
if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
{
/* Error */
EVP_CIPHER_CTX_cleanup(&ctx);
return 0;
}
fwrite(outbuf, 1, outlen, out);
}
if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
{
/* Error */
EVP_CIPHER_CTX_cleanup(&ctx);
return 0;
}
fwrite(outbuf, 1, outlen, out);
EVP_CIPHER_CTX_cleanup(&ctx);
fclose(in);
fclose(out);
return 1;
}
int main (int argc, char *argv[])
{
int iret;
char *s;
s = (char*)malloc(8+1);
strcpy(s, (char*)"password");
iret = do_crypt("test.txt", "test.bin", 1, s);
iret = do_crypt("test.bin", "test.bin.txt", 0, s);
return 0;
}
My simple makefile for building within demos of src:
Code:
CC=cc
CFLAGS= -g -I../../include -Wall
LIBS= -L../.. ../../libssl.a ../../libcrypto.a -lcrypto -ldl -pthread
EXAMPLES=main
all: $(EXAMPLES)
main: main.o
$(CC) -o main main.o $(LIBS)
clean:
rm -f $(EXAMPLES) *.o
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