On Tue, Aug 03, 1999 at 12:07:54PM +0200, Alberto Velo wrote:

> now I'd like to do a simple application, which gets an ascii input file and
> creates an encrypted (DES) output file.
> 
> I am able to do this with ssleay:
> ssleay.exe enc -des -in input.txt -out output.txt -e -a -k mypassword
> 
> I believe the des functions des_enc_read() or des_fcrypt() should be useful
> for me, [...]

They are not.  As noted in crypto/des/enc_read.c,

 *  -  The data format used by des_enc_write() and des_enc_read()
 *     has a cryptographic weakness: When asked to write more
 *     than MAXWRITE bytes, des_enc_write will split the data
 *     into several chunks that are all encrypted
 *     using the same IV.  So don't use these functions unless you
 *     are sure you know what you do (in which case you might
 *     not want to use them anyway).

And des_fcrypt is an implementation of the standard Unix password
encryption algorithm, which is just one way.  Also, DES keys are too
short to be really secure -- for "openssl enc", you could use, say,
-des_ede instead of -des.  (-des_ede is two-key Triple-DES).
Look at its implementation (apps/enc.c) to see what applications can
do to use the ciphers.
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