Topic: Cross Compiling wolfSSL Embedded SSL for uCLinux
2006-09-26 14:42:41 MDT
I'm cross-compiling yassl for a uClinux system.
I built wput against it's static library and brought it in.
I can't get it to establish a connection yet.
By adding some debug statements I found out that the key exchange was failing in
ret = RsaPublicEncrypt(ssl->preMasterSecret, SECRET_LEN, encSecret,
sizeof(encSecret), &key, &ssl->rng);
This happened because
key->n was larger than sizeof(encSecret)
key->n - 128
sizof(encSecret) - 96
As these numbers just so happen to be the byte length of the common 1024 and 768 bit keys respectively, I figured that wolfssl was probably just not providing enough memory for keys > 768 bits.
Hacking things around, I changed SECRET_LEN to 64 to bump it up to 1024 bits.
This allowed the key exchange to pass but causes a mac error, so I'm figuring there's another number or table in there that needs to change alongside of SECRET_LEN.
Am I on the right track?
Is there an established way to add support for larger keys?
Am I completely off?
2006-09-26 15:26:09 MDT
SECRET_LEN needs to stay at 48, per the standard. The bug is the length of encSecret, it shouldn't depend on SECRET_LEN. I just increased it to 256 to handle up to 2048 bit RSA. Thanks for the report.
2006-09-26 17:00:21 MDT
Thank you sir.
That little tip got my app working.
More testing is required but it certainly makes for a better nights sleep.