Edit - Cryptography Stack Exchange

You are not logged in. Your edit will be placed in a queue until it is peer reviewed.

We welcome edits that make the post easier to understand and more valuable for readers. Because community members review edits, please try to make the post substantially better than how you found it, for example, by fixing grammar or adding additional resources and hyperlinks.

Required fields*

Rev

Required fields*

best padding scheme for RSA

So i came across three padding scheme for RSA: PKCS1, PSS and OAEP. My intention here is to encrypt a file using AES key. then, encrypt the AES key with the RSA key and save the encrypted AES key along with the encrypted file. My question is which one of the padding schemes above best suits my purpose. Needless to say security is top priority for me and using compromised algorithm is off the table. Thanks in advance

Answer*

[PKCS#1][1] contains 4 padding schemes, of which only 2 are suitable for encryption, but only of small data blocks (like up to hundred bytes): the modern [RSAES-OAEP][2], and the obsolete [RSAES-PKCS1-v1_5][3] (which drawbacks include being harder to guard against decryption oracle attacks on the padding). PSS, aka [RSASSA-PSS][4], is strictly for signature.

For comfortable security, [AES-GCM-SIV][5] with a random 256-bit key encrypted per RSA-4096 using RSAES-OAEP with SHA-512 and MGF1 using SHA-512, would tick all the boxes (on crypto algorithm choices, ignoring implementation isssues) except resistance to hypothetical quantum computers usable for cryptanalysis. The modern baseline would be RSA-2048 using RSAES-OAEP with SHA-256 and MGF1 using SHA-256.

[1]: http://mpqs.free.fr/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp_EMC_Corporation_Public-Key_Cryptography_Standards_(PKCS).pdf
  [2]: http://mpqs.free.fr/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp_EMC_Corporation_Public-Key_Cryptography_Standards_(PKCS).pdf#page=16
  [3]: http://mpqs.free.fr/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp_EMC_Corporation_Public-Key_Cryptography_Standards_(PKCS).pdf#page=23
  [4]: http://mpqs.free.fr/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp_EMC_Corporation_Public-Key_Cryptography_Standards_(PKCS).pdf#page=27
  [5]: https://www.rfc-editor.org/rfc/rfc8452

Edit Summary*

Cancel

Add a comment |

Correct minor typos or mistakes
Clarify meaning without changing it
Add related resources or links
Always respect the author’s intent
Don’t use edits to reply to the author

create code fences with backticks ` or tildes ~
```
like so
```
add language identifier to highlight code
```python
def function(foo):
print(foo)
```
put returns between paragraphs
for linebreak add 2 spaces at end
_italic_ or **bold**
quote by placing > at start of line
to make links (use https whenever possible)

<https://example.com>

[example](https://example.com)

<a href="https://example.com">example</a>
MathJax equations $\sin^2 \theta$

formatting help »
answering help »

MathJax help »