>From: owner-openssl-us...@openssl.org On Behalf Of Peter Parker
>Sent: Tuesday, 20 November, 2012 20:59
>Subject: This is one for the Pros
Not really. This is pretty basic.
>I've been trying to generate a public/private key pair after
>generating the certificates, but OpenSSL keeps giving me an error.
>The commands and the error are below. Thanks.
No you're not; you're generating a CA keypair and cert (directly),
then an application keypair, then an application cert (via CSR).
Which is the (well, a) correct sequence, for one entity.
>Commands
>#openssl req -new -x509 -extensions v3_ca -days 365 -keyout caKey.pem
>-passout pass:test -out caCert.crt -batch
>#openssl genrsa -out application.pem -passout pass:test -des3 1028
1028 is an unusual size for an RSA key; most folks use power-of-2
based values like 1024 1536 2048. 1024 is presently rather marginal
for security; for example, NIST has it deprecated since the end of
2010, and prohibited after the end of 2013, for US government use.
>#openssl req -new -key application.pem -passin pass:test -out
application.csr -batch
A second req -new -batch generates a CSR with the same DN ...
>#openssl x509 -req -days 365 -in application.csr -CA caCert.crt
-CAcreateserial
>-CAkey caKey.pem -passin:test -out test-key.pem -extensions ssl_cert
... thus this creates a CA-signed cert which appears to be self-signed,
and will not chain correctly with OpenSSL. If the ssl_cert section of your
config file (which doesn't exist in the distro file) includes AKI, other
software that chains primarily by AKI may work, but this is still incorrect.
This puts the cert in a file named test-key.pem, which is a misleading name.
>#openssl rsa -in test-key.pem -passin pass:test -out pub-key.pem -outform
PEM -pubout
And therefore this command, which is not the last one, fails because
you told it to read the privatekey from a file which is a certificate.
application.pem is your privatekey.
>#openssl rsautl -encrypt -inkey pub-key.pem -pubin -in testfile.txt -out
eFile.ssl
>Error
>"unable to load Private Key" (I receive this after the last command)
Not last.
>The key thing that I am trying to do is to encrypt some files with the key
>that I generate. I do however want to use the public and private keys that
>I get out of the PEM file using the x509 (or the ca utilities).
If (any of) your files are larger than about 100 bytes (for 1024-bit RSA)
you can't use raw RSA; even if they aren't, you can't interoperate with
properly designed software that doesn't use raw RSA. The conventional
approach is to encrypt the "bulk" data symmetrically with a nonce key (DEK)
and PK (RSA) encrypt that DEK; there are numerous schemes that do this,
but the one that OpenSSL supports directly is PKCS7/CMS/SMIME. (CMS is an
updated Internet version of PKCS7, and SMIME is a simple wrapping of CMS.)
You can generate and use RSA keys without using certificates (and without
using the req x509 ca utilities) IF you have a way to "distribute" them
correctly -- that is, to make sure the "enveloper" always uses a correct
publickey for the recipient and not a forged, tampered, or obsolete one.
(And similarly the verifier for a signer.) Most standard schemes do use
X.509 certs for this purpose, because they are also standard.
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