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4 votes
Accepted

Message Authentication Code Padding Overview

CMAC is built from a block cipher, so at the lowest level it can only support messages whose length is an exact multiple of the blocklength. Thus, it must use a padding method to encode the input into ...
Mikero's user avatar
  • 13.4k
4 votes

Message Authentication Code Padding Overview

CBC-MAC is codified by ISO/IECĀ 9797-1:2011 (free preview at IEC), which has 4 padding methods. If $m$ is the data length in bits and $n$ the block size in bits: Padding Method 1: pad with $(-m)\bmod ...
fgrieu's user avatar
  • 142k
3 votes

Weird padding in Crypto.Util.Padding.pad() function in python

In the event that the plaintext is a multiple of the blocksize, PKCS#7 padding specifies that an additional block be added. For 128-bit blocksize, this block is all ...
Daniel S's user avatar
  • 23.9k
2 votes
Accepted

Necessity of all three MD-Compliant padding conditions

This is necessary since we want the padding at the end for performance reasons. We don't place it in the beginning or the middle since we may not have the means to process all the data. The end is the ...
kelalaka's user avatar
  • 48.7k
2 votes

How to handle padding when encrypting a value smaller than the block size

I want to encrypt numeric identifiers into ciphertexts that are deterministic and not too long. I am considering AES-128 in ECB mode to encrypt 64-bit integers. You are not considering ECB mode as ...
Maarten Bodewes's user avatar
  • 92.9k
2 votes

Is Bypassing Padding Verification in RSA-PSS Dangerous?

RSA based signature schemes generally fail badly when padding isn't verified. When the verifier checks the padding, each (salt,message) pair generates a single ...
Richard Thiessen's user avatar
1 vote

How to handle padding when encrypting a value smaller than the block size

Here is one possibility (using only a single blockcipher call) that would work and provide both confidentiality and integrity under the following conditions: The inputs are of fixed-size: 64 bits An ...
Marc Ilunga's user avatar
  • 3,258
1 vote
Accepted

Regarding: Pseudorandomness, Pseudorandomgenerators and Padding

I can give little comments about each of the three evoqued points: Padding and PRGs: One of the (main) points of using PRGs is to turn around the Shannon's famous "restriction": the key ...
canary's user avatar
  • 124
1 vote
Accepted

How to get the rest of 10 bytes (from total 32 bytes plaintext) of plaintext from a 48 byte ciphertext using AES-128 when knowing 22B of plaintext?

The IV is often placed in front of the ciphertext. If you CBC-decrypt with the wrong IV then the first 16 bytes of random bytes is produced, followed by the actual plaintext. With CBC the previous ...
Maarten Bodewes's user avatar
  • 92.9k
1 vote

CTF - AES Padding Oracle

I wonder if u solve this problem or not, I can obtain my script to u, just replace some minor part to make sure this script can work properly to solve your problem. If you'd like to know how this ...
sbk6401's user avatar
  • 11

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