Tagged Questions

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1answer
95 views

Is there an efficient way to hide the encrypted plaintext length with a block cipher?

In block cipher modes of operation for encryption on input of a plaintext of $N$ blocks (We assume that the input size is always a multiple of the blockcipher mode: $N·16$ bytes) the size of the ...
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1answer
124 views

How is block cipher padding verified for consistancy?

Under what circumstances is a decryption routine able to tell that the padding of a message is invalid? If a cipher text block where to be randomly modified, what is the probability that the padding ...
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1answer
116 views

Why does .NET's ECB mode implementation append a constant block to my ciphertext?

Consider the following code and output: ...
4
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1answer
482 views

Padding methods for block ciphers - PKCS7 vs ANSI X.923

I was looking through block cipher padding methods, and found two good candidates: ANSI X.923 - pad with zeros, then a final byte for the padding length, e.g. ...
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1answer
379 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 ...
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1answer
2k views

How to choose a padding mode with AES

Depending on the framework you are using, there are various padding modes that can be used with AES encryption. For example, with .NET we can choose PKCS7, ISO10126, ANSIX923, Zeros or None. I ...