# Tag Info

Accepted

### Largest integer factored by Shor's algorithm?

wondering what the largest integer is which they were able to factor with a small quantum computer This answer starts with two classes of factorization efforts: stunts and adiabatic quantum computing ...

### What is the maximum size of the plaintext message for RSA OAEP?

The input length of OAEP is directly specified in the standard: ...
• 87.1k
Accepted

### Argon2 output length and parameter storage?

You need to consider the weakest link property: a security system is never stronger than its weakest link. Since Argon2 is a password-based function, the weak link here is going to be the strength of ...
• 14.1k
Accepted

### 1 Billion Bit Encryption?

Examining his claims about "Thundercloud": You can use it with "any existing software, operating system, or device" (a massive amount of effort---by whom?) Has its "own cryptographic language that is ...
• 6,689

### What size should the HMAC key be with SHA-256?

The only rule for the key is that it should at least contain 256 bits of randomness. If the key is smaller you may not get the full security of HMAC-SHA-256. The full security of HMAC is basically ...
• 87.1k

### What is the minimum and maximum value of an RSA private exponent?

In summary: Modern practice is to fix a small public exponent $e$ such as $e=2^{(2^4)}+1=65537$, then choose a public modulus $N$ of $\text{nlen}$ bits (the key size) with large random prime factors ...
• 128k

### What is the history of recommended RSA key sizes?

512 bits (rounded down from the 664 bits or 200 digits in the patent) was recommended from its conception in 1974 and throughout the 1980s. Indeed, 463 bits was considered sufficient in the mid-1990s ...
Accepted

### What is the maximum key size for a 128 bit AES?

Despite similarities, it is really important to understand that passwords and cryptographic keys should not be carelessly conflated. Some important contrasts: Passwords are normally selected by ...
• 14.1k
Accepted

### Password entropy much lower than entropy of encryption keys. Why is this acceptable?

I know that humans would find it impossible to maintain a 128 bit password -- however, I wonder if there is some technical reason why a 52 bit password would not be as weak as a 52-bit encryption key ...
• 31.5k

### Is there any benefit from using SHA-512 over SHA-256 when AES just truncates it anyway?

SHA-512 has both a larger internal state and a higher number of rounds than SHA-256 - which means that it provides a higher bit strength. Somewhat surprisingly it may also outperform SHA-256, as it ...
• 87.1k

### Brute-forcing Symmetric Keys

No, it doesn't help. It doesn't hurt either; as long as you don't repeat keys, the probability of success is always the same. That is, if there are $2^n$ possible keys, and you test $\lambda$ of ...
• 135k
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• 9,869