Re: EVP_KDF-SSHKDF man page error?

[Kory Hamzeh <kory@xxxxxxxxxxxx>]

Thanks, Paul. I noticed the type values matched the RFC, but thought maybe it should be a string if that was the case.

I did find another issue:

 if (EVP_KDF_derive(kctx, out, &outlen, params) <= 0)




The actual value of ‘outlen’ should be passed, not the address.

Kory

On Mar 25, 2022, at 4:01 PM, pauli@xxxxxxxxxxx wrote:

It is correct, the KDF is expecting the characters 'A' through 'F' here.  This is what is specified in the RFC: https://datatracker.ietf.org/doc/html/rfc4253#section-7.2

That line of code ought to have cast to (char *) or type defined simply as char, but it is essentially correct.


Pauli

On 26/3/22 5:11 am, Kory Hamzeh wrote:

Hi All,

If you look at the example SSH KDF code here:

https://www.openssl.org/docs/manmaster/man7/EVP_KDF-SSHKDF.html

Specifically, these lines:

 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_SSHKDF_TYPE,
                                         &type, sizeof(type));
 The variable ‘type’ is defined as a “const char”, so an 8 bit integer. The compiler spits out a warning on that line. Is the example code correct?

 I wonder if it should be calling OSSL_PARAM_construct_int() and ‘type’ changed to ‘int’?

Thanks,
Kory