https://tools.ietf.org/html/rfc4086

java.security.SecureRandom part of Java Cryptographic Architecture

SecureRandom.getInstance("SHA1PRNG");

参考资料

[1]. http://stackoverflow.com/questions/13923247/does-the-sha1prng-algorithm-for-securerandom-use-dev-random-for-entropy
[2]. http://es.wikipedia.org/wiki/SHA1PRNG
[3]. Secure Password Storage - http://goo.gl/Spvzs
[4]. https://www-fourier.ujf-grenoble.fr/JC2/exposes/ruhault.pdf