QUESTION POSED ON: 19 June 2002
Would you please kindly confirm whether I have understood the following things right?
Triple DES supports 168-bit encryption with SHA-1 message authentication. Triple DES is the strongest cipher supported by SSL. Triple DES uses a key three times as long as the key for standard DES. Because the key size is so large, there are more possible keys than for any other cipher -- approximately 3.7 * 1050.
DES uses 56-bit keys -- only 56-bit keys. One can use smaller keys (by making sure only keys to 40 bit, for example, are generated. You cannot use keys larger than 56 bits. But, see below...
RC2 with 128-bit encryption and MD5 message authentication: Because the RC2
ciphers has 128-bit encryption, it is the second strongest next to triple DES, with 168-bit encryption. RC2 128-bit encryption permits approximately 3.4 * 1038 possible keys, making it very difficult to crack.
The larger the key space -- the set of all possible numbers from which to
pick a key -- the longer a brute-force attack would take, so the better.
Provided you use, e.g. The Microsoft(r) Strong Cryptographic Provider (MSCP)
and Microsoft(r) Enhanced Cryptographic Provider (MECP), what is meant by "two
key" vs. "three key" in the following context:
DES -- MSCP: 56 bits; MECP: 56 bits
Triple DES (two key) -- MSCP: 112 bits; MECP: 112 bits
Triple DES (three key) -- MSCP: 168 bits; MECP: 168 bits
And, how is two key vs. three key achieved?
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