Hello All
First, I am new to this great forum.
I have a challenge on my hand as follows. I am a long time libpq user but
have never used the BYTEA data type nor its related functions until now. I
have am writing an interface for a web based application written in C using
libmcrypt and, of course, libpq.
My problem seems to be proper preparation of encrypted data for insert into
a BYTEA column. For insertion, I properly process a file (byte-by-byte)
through mcrypt, then I use PQescapeByteaConn as (snippet) follows:
*while(readInputFile(file,buffer,sizeof(buffer),&bytes) == Success) {
mcrypt_generic(mfd,buffer,sizeof(buffer));
// buffer size == 1 byte dbuffer[i++] = *buffer; dbuffer[i] =
'\0'; // Time spent on string
sanity
}
close(inputFile);
sb = PQescapeByteaConn(dbconn,dbuffer,(size_t)strlen(dbuffer),&rl);
sprintf(query,"INSERT INTO crypto(uid,tdkey,ivkey,cdata,cfile)" //cdata is
a bytea column "VALUES('%s','%s','%s','%s','%s')", ebs->uid,ebs->crkey,ebs->crivs,sb,credf);
ebs->r=db_func_query(ebs->r,query,0,proc);
*
What I insert into the bytea column is \x748a590ffdb8dc748dd3fba...
Now sb returns these same bits consistently each time I run the same file
through mcrypt, using the same key/salt combo which I expect. However, I
cannot verify whether the the data inserted is what it should be since I
cannot decrypt. I've tried using PQunescapeBytea(data,&size) for the
decrypt preparation expecting pretty much the reverse of PQescapeByteaConn
but end up with garbage.
If anyone can lend me a good suggestion or example of properly preparing
binary data strings for pg insertion, i will be very much grateful.
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