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1d
comment Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?
Yes, I was primarily concerned about private key exposure at signing time, not bad RNG at key-generation time; if you've got bad RNG at key generation time, you're screwed eternally if you keep using that key.
1d
comment Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?
So, having a good RNG at key generation time is the main factor, and that is acceptable and true for almost all cryptographic operations. Since ED 25519 seems to not require a RNG at signature time (right?), its implementation isn't vulnerable to what I described, right?
1d
revised Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?
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1d
comment Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?
Perhaps a better question: are any elliptic curve algorithms not vulnerable to this problem?
1d
asked Is Curve25519 vulnerable to private key exposure in the case of a bad RNG?
Jun
21
awarded  Yearling
Jan
5
awarded  Popular Question
Aug
13
asked How does Diffie-Hellman key exchange work?
Jul
2
awarded  Curious
May
25
asked Why would splitting a password output be better than separate HMACs for encryption/authentication key derivation?
May
23
comment Encryption and HMAC key derivation
What advantages are gained by just splitting the output from scrypt in key derivation? Why is not using a HMAC as a PRNG a better option?
May
23
asked Encryption and HMAC key derivation
May
20
asked Common password derivation function for different encryption methods
Jun
23
accepted Implementing PKCS#7 Padding on a Stream of Unknown Length?
May
9
awarded  Scholar
May
9
accepted Does knowledge of original file size provide a cryptographic weakness?
May
9
comment Does knowledge of original file size provide a cryptographic weakness?
Right, and I need to be able to check passphrase validity really quickly without having to read through an entire file of 16GB in length ;)
May
9
comment Does knowledge of original file size provide a cryptographic weakness?
When I start receiving data, I'm not sure of its ultimate size. Therefore, I do a cumulative HMAC-SHA256 on each chunk just to be paranoid. It adds 16 bytes every $c$ bytes, where $c$ is the chunk size, so it's not the most efficient thing in the world, but it should work for my purposes.
May
9
asked Does knowledge of original file size provide a cryptographic weakness?
Feb
27
comment Deriving HMAC key and cipher key from passphrase?
$HMAC$ is basically the RFC-2104 implementation in Python.