Padding has two primary uses in cryptography, ensuring messages are the proper length necessary for certain ciphers (e.g., block ciphers) or to provide assurances not built into the core cipher (e.g., semantic security)
5
votes
3answers
935 views
In the SHA hash algorithm, why is the message always padded?
In the SHA hash algorithm the message is always padded, even if initially the correct length without padding; the padding is of the form "1" followed by the necessary number of 0s.
Why is it ...
6
votes
2answers
269 views
What is the key strength reduction encrypting only 160 bits of data using RSA1024 for signatures
I am attempting to determine the strength of an incorrectly implemented 1024 bit RSA signature scheme. The weakness in the implementation is that the padding data lacks random numbers. As a result, ...
2
votes
4answers
876 views
Why is padding used for RSA encryption given that it is not a block cipher?
In AES we use some padded bytes at end of message to fit 128/256
byte blocks. But as RSA is not a block cipher why is padding used?
Can the message size be any byte length (is the encrypting agent
...
2
votes
1answer
409 views
Is RSA of a random nonce with no padding safe?
Consider the following protocol: Bob has a private RSA key $B_{priv}$, and Alice knows the public key $B_{pub}$. Alice wants to send confidential messages to Bob (no integrity intended). To send a ...
0
votes
1answer
398 views
Removing Padded Value in Decrypted Message
How to remove padded value in Decrypted Message?
I am using AES Algorithm..
ex:
this is the decrypted message..
"abcdefghijklmn "
there is a 2 space in that decrypted message which is equivalent ...
2
votes
3answers
425 views
Hash function in PBKDF2
From this excellent answer I learned (correct me if I am wrong) that when writing a block cipher with say key size 128 bit, one has to pad the password given (variable size) so that it becomes exactly ...
4
votes
2answers
297 views
Does RSA padding have to be unpredictable if the payload is?
I'm trying to understand the precise requirements on padding when using RSA for encryption.
Suppose Alice uses RSA to encrypt a payload $M$ that cannot be guessed (say, a random nonce): Alice send ...
