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For example, encryption using an oversimplified three-round cipher can be written as = ((())), where C is the ciphertext and P is the plaintext. Typically, rounds R 1 , R 2 , . . . {\displaystyle R_{1},R_{2},...} are implemented using the same function, parameterized by the round constant and, for block ciphers , the round key from the key ...
The Microsoft Windows platform specific Cryptographic Application Programming Interface (also known variously as CryptoAPI, Microsoft Cryptography API, MS-CAPI or simply CAPI) is an application programming interface included with Microsoft Windows operating systems that provides services to enable developers to secure Windows-based applications using cryptography.
Gpcode.AK, an early June 2008 computer virus for Microsoft Windows, which takes documents hostage for ransom by obscuring them with RC4 and RSA-1024 encryption; PDF; Skype (in modified form) [67] Where a protocol is marked with "(optionally)", RC4 is one of multiple ciphers the system can be configured to use.
Figure 1. One MD5 operation. MD5 consists of 64 of these operations, grouped in four rounds of 16 operations. F is a nonlinear function; one function is used in each round. M i denotes a 32-bit block of the message input, and K i denotes a 32-bit constant, different for each operation. <<< s denotes a left bit rotation by s places; s varies for ...
The Advanced Encryption Standard uses a key schedule to expand a short key into a number of separate round keys. The three AES variants have a different number of rounds. Each variant requires a separate 128-bit round key for each round plus one more. [note 1] The key schedule produces the needed round keys from the initial key.
The protocol exists in two versions, MS-CHAPv1 (defined in RFC 2433) and MS-CHAPv2 (defined in RFC 2759).MS-CHAPv2 was introduced with pptp3-fix that was included in Windows NT 4.0 SP4 and was added to Windows 98 in the "Windows 98 Dial-Up Networking Security Upgrade Release" [1] and Windows 95 in the "Dial Up Networking 1.3 Performance & Security Update for MS Windows 95" upgrade.
The round function is used for both key expansion and encryption/decryption. The key expansion process transforms the 64-bit data key and 256-bit key expansion key into a 256-bit execution key, consisting of 4 pairs of 32-bit numbers K R 0 , K L 0 , . . .
The encryption process consists of updating the state with four round functions over 10 rounds. The four round functions are SubBytes (SB), ShiftColumns (SC), MixRows (MR) and AddRoundKey (AK). During each round the new state is computed as S = A K ∘ M R ∘ S C ∘ S B ( S ) {\displaystyle S=AK\circ MR\circ SC\circ SB(S)} .