3,156 reputation
618
bio website ripple.com
location Northern California
age 44
visits member for 2 years, 8 months
seen Mar 15 at 23:00

I am Chief Cryptographer at Ripple Labs (formerly OpenCoin) and one of the architects of the Ripple payment system.


Aug
23
comment Taking advantage of one-time pad key reuse?
For example, every zero in the output indicates a matching byte in the two inputs.
Aug
23
comment How can I use asymmetric encryption, such as RSA, to encrypt an arbitrary length of plaintext?
RSA is a primitive. It needs to be assembled into a system to be useful. The short answer -- pick any encryption system that is known to be secure, uses the RSA primitives, and that provides the characteristics you want (for example, supporting long blocks of plaintext). Length is not the only reason the RSA primitives are generally unsuitable for direct use.
Aug
23
comment Looking for cryptographic secure hash algorithm(s) that produces identical root hash for differently sliced hash list
You can populate the tree any way you want. So long as the final tree is the same in all cases, the hashed output will be the same. This generally solves the real problem people have when they ask the question asked here. Skein has a specific mode for this.
Aug
23
comment Is digest=HASH(HASH(a)+HASH(b)) equivalent to publishing two digests?
If at all possible, you really want the algorithm to have the characteristic that collisions are only possible if two different inputs hash to the same output of the hash function. If there is any possible way to do it this way, do it that way.
Aug
22
answered Is the number of creatable torrents limited?
Aug
20
comment How can SSL secure a two-way communication with only one key-pair?
If you think about it, if you have secure one-way communication, you have secure two-way communication (assuming you have a two-way communication channel at all). If I have a secure path to you, I can make up a random key, send it to you over that path, and then you can use that to encrypt messages to me, giving you a secure path to me.
Aug
18
answered Is public-key cryptography the only option in this scenario?
Aug
14
answered How can SSL secure a two-way communication with only one key-pair?
Aug
14
answered Why does PBKDF2 xor the iterations of the hash function together?
Aug
14
comment Is HTTPS secure if someone snoops the initial handshake?
If that were true, HTTPS would utterly fail to do the one thing it is specifically intended to do. So of course it's not true.
Aug
14
awarded  Supporter
Aug
14
awarded  Editor
Aug
14
revised Is calculating a hash code for a large file in parallel less secure than doing it sequentially?
added 1 characters in body
Aug
13
awarded  Teacher
Aug
13
answered Is calculating a hash code for a large file in parallel less secure than doing it sequentially?