Key-recovery attack

A key-recovery attack is an adversary's attempt to recover the cryptographic key of an encryption scheme.:52 Historically, cryptanalysis of block ciphers has focused on key-recovery, but security against these sorts of attacks is a very weak guarantee since it may not be necessary to recover the key to obtain partial information about the message or decrypt message entirely.:52 Modern cryptography uses more robust notions of security. Recently, indistinguishability under adaptive chosen-ciphertext attack (IND-CCA2 security) has become the 'golden standard' of security.:566 The most obvious key-recovery attack is the exhaustive key-search attack. But modern ciphers often have a key space of size 2 128 {displaystyle 2^{128}} or greater, making such attacks infeasible with current technology. A key-recovery attack is an adversary's attempt to recover the cryptographic key of an encryption scheme.:52 Historically, cryptanalysis of block ciphers has focused on key-recovery, but security against these sorts of attacks is a very weak guarantee since it may not be necessary to recover the key to obtain partial information about the message or decrypt message entirely.:52 Modern cryptography uses more robust notions of security. Recently, indistinguishability under adaptive chosen-ciphertext attack (IND-CCA2 security) has become the 'golden standard' of security.:566 The most obvious key-recovery attack is the exhaustive key-search attack. But modern ciphers often have a key space of size 2 128 {displaystyle 2^{128}} or greater, making such attacks infeasible with current technology.