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1 vote

Could this method allow two people using weak cryptography to bootstrap their way to unbreakable cryptography (e.g. otp)

The fundamental issue: Alice does not only have access to weak encryption. Alice has access to oh-so totally unbreakable for ever encryption. But she does have to have £5 (the going rate for complete ...
Paul Uszak's user avatar
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0 votes

Why not flip random bits of the encrypted message for additional security? (hybrid system)

A variation of your idea called Key-Whitening was used by Ron Rivest (the R in RSA) to strengthen the DES by XORing an extra 64-bit key to the input and yet another extra 64-bit key to the output of ...
garfunkel's user avatar
0 votes

Symmetric encryption with compromised key but partially compromised message

Often the plaintext & therefore ciphertext message is larger than the key. Usually the amount of bits in the ciphertext message is as large as the plaintext message + possibly some overhead. For ...
Maarten Bodewes's user avatar
  • 93.2k
4 votes

Why is the ciphertext output 32 bytes long when i encrypt a 16 bytes long plaintext by using AES-128-CBC

CBC mode requires A nonce ( it was stated as IV for CBC but it is nonce - number used once); so that we can have probabilistic encryption, i.e. even if we have the same plaintext and ciphertext we ...
kelalaka's user avatar
  • 49k
4 votes
Accepted

Can the RSA public key be used for both encryption and decryption?

The standard convention in asymmetric cryptography (thus RSA), is that key generation generates a key pair comprising a public key and a private key, and unless otherwise stated the public key is ...
fgrieu's user avatar
  • 142k
2 votes

Time taken for a brute force attack on a key size of 64-bits

@MaartenBodewes's using the observation that "the key may be either on the lower half or higher half of the key space" to derive the average time is very clever. In my answer, I want to give ...
Guanyuming He's user avatar
2 votes
Accepted

Why not flip random bits of the encrypted message for additional security? (hybrid system)

Your proposal boils down to introducing a second key, and using it to perform a simple xor encryption. If you have so little confidence in the first algorithm that you would not use it as-is, you ...
bmm6o's user avatar
  • 1,102
1 vote

Why not flip random bits of the encrypted message for additional security? (hybrid system)

Before sending the message, person A flips all the bits whose indexes are in $s$. E.g. if $s={1,2,3}$ the bits number $1,2,3$ would be flipped. This is not secure. You might say that only half of the ...
Maarten Bodewes's user avatar
  • 93.2k
1 vote

Getting the slope of a public key given its x and y coordinates

Since you are talking about ECC and we are in a crypto stack exchange, I suppose you define your elliptic curve over a finite field, lets say $\mathbb{F}_q$. Here is a tool that lets you plot elliptic ...
Alex Them's user avatar
  • 322
1 vote

"Appendable" encryption scheme

This is a function of stream ciphers that are not plaintext aware - which is usually the case. These ciphers have a random access property which allows you to encrypt / decrypt any byte in the stream. ...
Maarten Bodewes's user avatar
  • 93.2k

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