Why is there a limited set of OpenSSL engine algorithms chosen in crypto.c (code below)?
log_engine("RSA", ENGINE_get_default_RSA()); log_engine("DH", ENGINE_get_default_DH()); log_engine("RAND", ENGINE_get_default_RAND()); log_engine("SHA1", ENGINE_get_digest_engine(NID_sha1)); log_engine("3DES", ENGINE_get_cipher_engine(NID_des_ede3_ecb)); log_engine("AES", ENGINE_get_cipher_engine(NID_aes_128_ecb));
Crypto hardware may be able to support various modes/key sizes and I would have thought one would want to support the algorithms allowed in TLS from the tor spec (MUST support SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA and SHOULD TLS_DHE_RSA_WITH_AES_128_CBC_SHA).
Also, I was a bit surprised to see ECB mode. Is it true that ECB, when used as a stream generator, is equal to CTR mode? ECB mode is not mentioned in the spec and after some digging, I found a reference to it [1] for encrypting at most one block length of data in the header.
To rephrase the opening question, it appears, by my limited review, that there is support for only a subset of the algorithms that Tor uses; what are the implications of increasing this support?
Thanks,
Josh
[1] https://lists.torproject.org/pipermail/tor-commits/2012-July/044878.html
p.s. My motivation for this question is that I'm trying to optimize the performance of the TI AM335X for use on the BeagleBone Black. While it can't compete with high end servers, it appears to hold its own behind a home network. Unfortunately, the processor doesn't support any asymmetric algorithms, which would help in circuit creation, but it does support various flavors of AES as well as SHA1.