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visits member for 3 years, 7 months
seen Jun 25 at 11:00

I'm an engineer with experience in applied cryptography, in particular in Smart Card systems.

Feel free to edit my answers to fix obvious errors, or improve them on expression (I'm not a native English speaker).


Mar
18
awarded  Nice Answer
Mar
18
revised Is using the concatenation of multiple hash algorithms more secure?
Slightly trim
Mar
18
revised Is using the concatenation of multiple hash algorithms more secure?
Stress that the second paragraph applies to password hashing
Mar
18
comment Is using the concatenation of multiple hash algorithms more secure?
@Patrick M: indeed, and that's what I'm saying in the second paragraph. I'll make it clearer that it applies to password hasing (even though the question has been edited to make it clear password hashing is not the focus).
Mar
18
revised Is using the concatenation of multiple hash algorithms more secure?
Fix it for good
Mar
17
comment Is using the concatenation of multiple hash algorithms more secure?
@Ismael Miguel: good suggestion, done.
Mar
17
revised Is using the concatenation of multiple hash algorithms more secure?
Integrate a convincing example proof in the answer, per suggestion in comment
Mar
17
revised Is using the concatenation of multiple hash algorithms more secure?
Fix a serious problem with the section on first-preimage resistance; give a short definition of each classic property.
Mar
17
comment Is using the concatenation of multiple hash algorithms more secure?
@Ismael Miguel: I did mean at least as secure in the first paragraph. As in: the concatenation of MD5 and (full) SHA-512 is at least as secure as (full) SHA-512, WRT collision-resistance (also second-preimage-resistance). Proof: hypothetical colliding messages for the 640-bit MD5||SHA-512 also collide for SHA-512, thus if SHA-512 is secure, then MD5||SHA-512 is secure.
Mar
17
awarded  Critic
Mar
17
revised Is using the concatenation of multiple hash algorithms more secure?
polish
Mar
17
revised Is using the concatenation of multiple hash algorithms more secure?
Comment about the example
Mar
17
comment Is using the concatenation of multiple hash algorithms more secure?
The "128 bit MD5 and 128 bit SHA512 will only be as collision-resistant as the weaker of the two" part of this answer is wrong. As an illustration, we can find new MD5 collisions at high rate, but there is no known collision for SHA512 truncated to 128 bits, thus no known collision for the 256-bit concatenation of MD5 and SHA512 truncated to 128 bits.
Mar
17
comment Is using the concatenation of multiple hash algorithms more secure?
This answer is oriented toward password hashes, and does not apply well to the question as it stands after edit.
Mar
17
revised Is using the concatenation of multiple hash algorithms more secure?
edited body
Mar
17
answered Is using the concatenation of multiple hash algorithms more secure?
Dec
10
awarded  Autobiographer
Nov
27
comment How is security of server's RSA private key is ensured?
@Herr K: On a server connected to using https, the key needs to be used to demonstrate the server's identity for each new connection. It is thus "live" somewhere, and no password-protection can help that. If the key is in the server's CPU+RAM, and the server is rooted, the key is in danger. As explained, the HSM slightly helps to mitigate that risk, for there is good assurance that the key won't leak from it.
Nov
27
revised How is security of server's RSA private key is ensured?
Polish
Nov
26
awarded  Yearling