Apr 21
Finish up encryption :
Tools:
- http://www.openssl.org/ - command line & system crypto swiss army knife
- http://www.gnupg.org/ - personal communication key management and crypto
- https - encrypted web browsing (i.e. going online to your bank)
- ssh - secure shell (remote encrypted login)
cryptographic hash
Desired properties: short, unique file id; cannot match given key with another file.
$ md5 <file>
MD5 (<file>) = 78f85b414b3a686a9a8932b32156d024 # 32 hex (4bit) chars
$ openssl md5 <file>
$ openssl sha1 <file>
SHA1(jim_mt_mansfield.jpg)= 3d6d3cb68e47590c8a4c779ed802e3e6c6750c4f
40 hex (4 bit) chars
symmetric key
Discuss general idea, "cipher block chain", key length, do an example with openssl.
asymmetric public/private key
RSA, as discussed
Trust: how do you know the public key is correct?
cryptanalysis
How do you attack these things?
- cipher text only
- known plaintext
- chosen plaintext
- side channel attacks
- timing
- traffic analysis
- social engineering
