> From: owner-openssl-us...@openssl.org On Behalf Of Panikulam Vivek
> Sent: Monday, 20 September, 2010 10:52
> I am using the below openssl command to encrypt a string using a
> public key and get a binary output (symm_key_string_enc.txt). Is this
> an example of assymetric encryption?
Yes, a simple one. Actual crypto schemes need to tie together
the recipient key identity in some form, the encrypted-DEK,
usually an IV, and the encrypted data under it. The encrypted key
*by itself* is not useful, and a mix-up of which keys to use
when is worse than useless. Besides SSL see e.g. CMS PGP SMIME.
> and is there a way to get the output in a text/ASCII format?
> openssl rsautl -encrypt -inkey pub_key.txt -pubin
> -in symm_key_string.txt -out symm_key_string_enc.txt
Directly in rsautl, -hexdump displays in a form good for humans
to read, but not particularly convenient for another program.
If you want the latter, base64 is the most common method
but far from the only one. You can put the binary in a file
as you did and then encode to base64 e.g.
openssl base64 -e -in symmkey_enc -out symmkey_enc_b64.txt
# or less mnemonically
openssl enc -a -e -in symmkey_enc -out symmkey_enc_b64.txt
There are lots of other tools that can display, or convert,
a binary file in various human-readable forms. Unix (and
quasi-Unix like cygwin) has 'od' standard, and there are
any number of 'progammer's editors' for many system types.
I think it's a poor idea to label files .txt if they aren't
(at least) readable chars, and I hope your symmetric keys
aren't; that would reduce your keyspace unnecessarily.
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