An exciting day for Symbian developers, you no longer need to rely on OpenSSL for all your crypto needs (at least for 9.1+...) because the Symbian crypto library headers and libs are at long last published...
Get them here: http://developer.symbian.com/forum/ann.jspa?annID=14
The crypto library adds asymmetric ciphers RSA, DSA and DH and symmetric ciphers AES, 3DES, DES, RC4, RC2 to the already published hash library.
In addition, you get a trimmed down version of the big integer library including support for generating large primes, various sorts of block cipher padding, and PBE.
No PKCS decoders or unified keystore published yet, we can but hope.