Linked Questions

2 votes
1 answer

How many bits of symmetric security does RSA-3072 actually provide? [duplicate]

I know that the sizes are standardized to $1024$, $2048$ etc. but they actually provide different security than $128$, $256$... for example $\texttt{RSA-}2048$ is actually $112$ bits of security and $...
TheCuriousCrypter's user avatar
3 votes
2 answers

Why are recomended RSA key lengths so high? [duplicate]

I was checking for authoritative sources to back up my recommendation of a minimum RSA key length of 1024 and was shocked to find that NIST 800-56Br1 and FIPS 186-4 both recommend at least 2048 bits ...
JaimeCastells's user avatar
1 vote
1 answer

Equivalent RSA modulus for NIST P-192 and P-521 elliptic curves [duplicate]

At, I found the following table of ECC field size and the corresponding RSA modulus recommended by NIST. ECC Modulus RSA Prime Size 160 1024 224 2048 ...
satya's user avatar
  • 1,414
0 votes
0 answers

To get 128-bit security for RSA, the modulus should be 4096 bits. How was that determined? [duplicate]

My understanding of security level is that for a crypto scheme to have n-bit security means it would take $2^n$ operations to break it. For something like AES with a 128-bit key, it's straight-...
Bastien's user avatar
  • 511
132 votes
7 answers

How big an RSA key is considered secure today?

I think 1024 bit RSA keys were considered secure ~5 years ago, but I assume that's not true anymore. Can 2048 or 4096 keys still be relied upon, or have we gained too much computing power in the ...
Inaimathi's user avatar
  • 1,587
26 votes
2 answers

Why is it not possible to increase the size of RSA keys indefinitely?

According to this primer on elliptic curves by Ars Technica, when composite numbers get "too" big, they become easier to factorize with Quadratic Sieve and General Number Field Sieve. While this is ...
fast-reflexes's user avatar
10 votes
3 answers

1 Billion Bit Encryption?

So, browsing through YouTube, I stumbled on this video interview of John Draper (Captain Crunch), one of the first "hackers". He talks for about 3 minutes (until 27:48) about his home rolled ...
Tanner's user avatar
  • 111
16 votes
1 answer

How long does it take to crack RSA 1024 with a PC?

Using an Intel Core i5 CPU, how long does it take to crack RSA using a key size of 1024 bit (generated using a secure key pair generation function)? Suppose for instance that we have thousands of ...
R1w's user avatar
  • 1,960
13 votes
1 answer

How much stronger is RSA-2048 compared to RSA-1024?

How much stronger is RSA-2048 compared to RSA-1024? It is hard to imagine very big numbers. So what would be your way to explain the difference to someone who doesn't know much about cryptography?
user27296's user avatar
  • 131
16 votes
2 answers

How do I get the equivalent strength of an ECC key?

I know how to calculate the comparable symmetric strength of an RSA modulus: calculate the running time for a field sieve. This is how NIST gives approximate symmetric sizes for asymmetric algos in ...
mikemaccana's user avatar
13 votes
3 answers

What does "export grade" cryptography mean? And how is this related to the Logjam attack?

I am doing some research on the Logjam attack, and I need help in learning some terms that are new for me. What does "export grade" cryptography mean? And how is this related to the Logjam attack?
han's user avatar
  • 419
10 votes
2 answers

Why is the complexity of RSA-1024 80 bit and not 86 bit?

Why is the complexity of RSA-1024 80 bit and not 86.76611925028119 bit? Here is the complexity for the GNFS (pulled from the linked Wikipedia article): $$\exp\left( \left(\sqrt[3]{\frac{64}{...
user129789's user avatar
7 votes
1 answer

How Secure is gpg Command Using Symmetric AES-256 From Being Cracked

How secure is any data encrypted using the following command: gpg -o *encrypted_output_file_name* --symmetric --cipher-algo AES256 *file_to_be_encrypted* Can ...
Arjun's user avatar
  • 171
6 votes
2 answers

Difficulty of breaking RSA for a given key size

Is it true that breaking a 1024-bit RSA key is as difficult as breaking a 128 bit symmetric key (e.g. AES)? I know that breaking a RSA key is equivalent to factoring the modulus $N$. To factor it, you ...
Ashwin's user avatar
  • 303
4 votes
2 answers

Is it hypocritical to use AES-256 and RSA 2048 in the same application?

I see a common claim that AES-256 is the gold standard and is good future proofing, often in the same wind as "just use 2048-bit keys for RSA". Security documents seem to recommend both AES-256 and ...
Shruggie's user avatar
  • 237

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