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Cryptographic hash functions by design cannot be collision-free since they operate on arbitrary-sized input to fixed-sized outputs sizes $$H:\{0,1\}^* \to \{0,1\}^b$$ where $b$ is the $H$'s output si …

If we assume that 1 and 2 are true then HMAC-SHA-512 is a better choice. For the time comparison, as stated Paul Uzsak, if there is no specific time relevant problem around ~50% faster shouldn't be c …

The other answers did not mention the Length-Extension attacks on the Merkle–Damgård construction. Length extension is given a hash value $h$; $$h = \operatorname{SHA-256}(\text{IV},\text{secret_key}\ …

It is the byte padding of SHA-512 encoded as the big-endian, simply add bit 1, that is the last 0x80 in the begging part fill zeros then add the size in the 128-bit big-endian in the end. 0x18 is 24 …

Hash functions operate on blocks like SHA-256 has 512-bit input block. In SHA-256, your data $m$ is divided into 512-bits blocks $m_1,\ldots,m_n$ where each entered into the hash function. The final b …

$2^{64-1}$ bits that make 2.30584301 exabytes *. If you are not restricted to SHA256, then use SHA512 that allows files to have size at most $2^{128}-1$, or use SHA3 that has no limit. The NIST must u …

Stream cipher from hash functions: possible For any cryptographically strong pseudo-random function (PRF) the CTR mode of encryption can be defined. You can build such a PRF from a hash function. On …

The truncated versions of SHA2 are introduced in 2005 and in the Cryptographic hash Workshop, in 2005, Kelsey listed the reasons as; Interoperability and security reasons Need drop-in replacement for …

AES-128 (2000) has been around for 20 years and there is no attack faster than brute-force, except the multi-target that affects all block ciphers and hash algorithms. As you can see, an algorithm can …

First of all, the output sizes of SHA2 are 224, 256, 384 or 512-bit and of SHA3 are 224,256, 384, 512-bit. Normally, hash functions are accepting arbitrary length inputs and producing fixed-length o …

Could is also be possible to generate $H(\text{message}[1..n-1])$ from $H(\text{message}[1..n])$ if I know the last byte? No, the length extension attacks are not working exactly like that. Let see …

The $\operatorname{SHA-224}$ is defined in the exact same manner as $\operatorname{SHA-256}$ with different initial values and the digest is obtained truncating the hash value, FIPS PUB 180-4 Page 23. …