# Re: make one symmetric key of two symmetric keys

*From*: "Ulf Reiman" <ulf.reiman@xxxxxxxxx>*Date*: 23 Feb 2006 07:00:52 -0800

No, no superencryption, a wonder how do combine two symmetric keys to

one, assume two 128 bits key K1 and K2, is it safe to do K3=K2 (XOR)

K1, or is it more safe to do K3 =H(K1) + H(K2), if 2 hashes equals 128

bits. Another question is, assume that K1 is broken by some adversary,

is it them safe to do K3=K2 (XOR) K1, or does the broken K1 give to

mush information about K3. Is it then safer to do K3 =H (K1) + H (K2)?

If hashing is better can you give me a appropriate hash function.

Regards

Ulf Reiman

Ludovic Joly skrev:

Sounds like you want to achieve superencryption some way. If so just

google this term. It's well documented and you'll find lots of useful

and interesting resources.

Kind regards

Ludovic Joly

.

**Follow-Ups**:**Re: make one symmetric key of two symmetric keys***From:*Ludovic Joly

**References**:**make one symmetric key of two symmetric keys***From:*Ulf Reiman

**Re: make one symmetric key of two symmetric keys***From:*Eric Lalitte

**Re: make one symmetric key of two symmetric keys***From:*Ulf Reiman

**Re: make one symmetric key of two symmetric keys***From:*Ludovic Joly

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