DES Modes of Operation. Federal Information Processing Standards Publication 81, December, 1980.  Home/Search   Document Not in Database   Summary   Related Articles   Check

..... that is equal to encrypt(23; Tom; 70K; Maple; 40) The second is encrypted to 1000000000011101. equal to encrypt(860; Mary; 60K; Main; 80) We treat the encryption function as a black box in our discussion. Any block cipher technique such as AES [1] RSA [11] Blow sh [12] DES [3] etc. can be used to encrypt the tuples. The second column corresponds to the index on the employee ids. For example, value for attribute eid in the rst tuple is 23, and its corresponding partition is [0; 200] Since this partition is identi ed to 2, we store the value 2 as the identi er ....

DES. Data Encryption Standard. FIPS PUB 46, Federal Information Processing Standards Publication, 1977.

....the row is accessed by the DBMS. We registered an encryption decryption edit routine for the tables. When a read write request arrives for a row in one of these tables, the edit routine invokes encryption decryption algorithm, which is implemented in hardware, for whole row. We used the DES [3] algorithm option for encryption hardware. 5.3. Encryption scheme alternatives We did not consider all possible combinations of different encryption approaches, namely; software and hardware level encryption, and different data granularity. We started with software encryption at field level. As ....

DES. Data encryption standard. FIPS PUB 46, Federal Information Processing Standards Publication, 1977.

....procedures are used to insure an unbroken chain of authenticated associations within the synchronization subnet to the primary servers. An authenticator, consisting of a key identifier and encrypted checksum, is computed using the DES encryption algorithm [9] and DES cipher block chaining method [10]. Some implementations incorporate special provisions to compensate for the delays inherent in the encryption computations. Careful consideration was given during design to factors affecting network overheads. Some of the present Internet time servers operate with over 100 peers and a few operate ....

DES Modes of Operation. Federal Information Processing Standards Publication 81. National Bu13 reau of Standards, U.S. Department of Commerce, December 1980.

....1 : b n . High Level Overview The encryption function DFC operates on 128 bit message blocks by means of a secret key K of arbitrary length, up to 256 bits. Encryption of arbitrary length messages is performed through standard modes of operation which are independent of the DFC design (see [2]) The secret key K is first turned into a 1024 R 0 R 1 R 9 R 8 RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe RF Phi r oe oe hhhhh h ( hhhhh h ( hhhhh h ( ....

DES Modes of Operation. Federal Information Processing Standard Publication 81, U. S. National Bureau of Standards, 1980.

....by means of a secret key K of arbitrary length, up to 256 bits. The corresponding decryption function is DFC Gamma1 K and operates on 128bit message blocks. Encryption of arbitrary length messages is performed through standard modes of operation which are independent of the DFC design (see [2]) The secret key K is first turned into a 1024 bit Expanded Key EK through an Expanding Function EF, i.e. EK = EF(K) As explained in Section 1.5, the EF function performs a 4 round Feistel scheme (see Feistel [8] The encryption itself performs a similar 8round Feistel scheme. Each round ....

....MHz 128 MB RAM with OSF1 V4.0 878. Compiled with DEC TM cc 5.6 071. 4 Extension and Uses 4.1 Different Modes The DFC algorithm is presented as a 128 bit message block cipher. It can be extended by standard ways in order to encrypt a message of arbitrary length, for instance, with the CBC mode [2]. 4.2 Encryption with 64 Bit Blocks Some applications do not need 128 bit message blocks, and 64 bit ones are enough. We can adapt the DFC algorithm in a straightforward way. We use a 8 round Feistel cipher with a new RF 0 function which acts on 32 bit strings with a 64 bit string parameter ....

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DES Modes of Operation. Federal Information Processing Standard Publication 81, U. S. National Bureau of Standards, 1980.

....of plaintext P i using key K. The corresponding decryption is written P i = K Gamma1 [C i ] The symbol Phi denotes bitwise exclusive OR. If a number is written with a subscript, that subscript denotes the base; unsubscripted numbers are in base 10. 2. 2 Cipher Block Chaining CBC encryption [NBS80] operates by encrypting the exclusive OR of each plaintext block and the previous ciphertext block: C i = K[P i Phi C i Gamma1 ] To encrypt the first plaintext block, C 0 is set to the initializaton vector (IV) IVs may be agreed upon in advance, transmitted encrypted, or transmitted in the ....

NBS. DES modes of operation, December 1980. Federal Information Processing Standards Publication 81.

....to show how much probable plaintext is available. We also show how traffic analysis is a powerful aid to the cryptanalyst. We conclude by outlining some likely changes to the underlying protocols that may strengthen them against these attacks. 1 Introduction DES, the Data Encryption Standard [NBS77], is a strong cipher that is hobbled by an overly short key. This criticism is not new [DH77] more recently, designs have been published for machines that can exhaustively search the key space in a short time for a comparatively modest investment [Wie94] Most such designs assume blocks of known ....

NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....prying eyes of the enemy. To emphasize that the same secret key is used by both the ecrypter and decrypter, secret key cryptosystems have also been called one key cryptosystems and symmetric cryptosystems. Perhaps the best example of secret key cryptosystems is the Data Encryption Standard (DES)[3, 4, 5]. In DES, the plaintext X, the cryptogram Y , and the key K are binary sequences with lengths M = 64; N = 64 and L = 56, respectively. All 2 64 possible values of X are, in general, allowed. In its so called electronic code book mode, successive 64 bit blocks of plaintext are enciphered using ....

DES modes of operation, National Bureau of Standards (U.S.), Federal Information Processing Standards Publication 81, National Technical Information Service, Springfield, VA, Dec. 1980.

....a 1,000,000 machine can search the entire 56 bit DES keyspace [Wie94] Since both our ESM and telnet process typical user to host session traffic, a character oriented cipher mode that can encrypt and decrypt each character as received is needed. Our choice is 8 bit Cipher Feedback (CFB) mode [NBS80]. CFB has the advantage of eventually resynching the cryptographic stream over a channel that occasionally inserts or deletes traffic. This turns out to be an important property in this application; even though telnet uses reliable TCP channels, its own protocol processing can drop characters ....

NBS. DES modes of operation, December 1980. Federal Information Processing Standards Publication 81.

....any transport mechanism. A session key hash, suitable for use as a challenge, is displayable on the local side and is available in the environment on the remote side. There is no other authentication or protection against an active attack. 4 Cryptographic considerations We use triple DES [NBS77] as our bulk encryption cipher; its 168 bit effective keyspace is well above the reach of exhaustive search. We opted for triple DES because we feel that standard DES is no longer secure against exhaustive search. Even today, it appears that a 1,000,000 machine can search the entire 56 bit DES ....

NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....key schedule is examined. Finally, implications on the security of MacGuffin are discussed. 1 Introduction The principles of block cipher design have been a focus of intense research in cryptography for the past two decades. The public unveiling of DES (the NBS Data Encryption Standard [1]) was a major landmark in the study of block ciphers, arousing interest in cryptography and cryptanalysis. By modifying a design element of DES and studying how this change affects security, researchers have gained insight into the exceptional strength of DES in particular and Feistel ciphers in ....

....examine the cryptographic strength of MacGuffin and to test that central hypothesis. 2 Description of MacGuffin and DES This section provides only a cursory introduction to DES and MacGuffin. A more comprehensive treatment can be found in many texts the original DES standard can be found in [1], while [4, 6, 7] provide more readable descriptions. MacGuffin is fully described and implemented in [5] For a general introduction to cryptography and block ciphers, the reader is referred to [4, 8, 6, 7, 9] 2.1 DES In any (balanced) Feistel network, the plaintext block is split up evenly ....

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NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....we design a statistical plaintext recognizer suitable for use in a ciphertext only key search machine. Software simulations indicate that this design gives a powerful attack on the encryption of low entropy data. 1 Introduction Ever since the Data Encryption Standard (DES) was announced [1], researchers have worried about its relatively short key size. Its cryptographic strength notwithstanding, 56 bits seemed vulnerable to exhaustive search. Diffie and Hellman quickly concluded that a highly parallel custom designed machine could indeed mount a successful brute force attack on DES ....

NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....b 1 : b n . High Level Overview The encryption function DFCK operates on 128 bit message blocks by means of a secret key K of arbitrary length, up to 256 bits. Encryption of arbitrarylength messages is performed through standard modes of operation which are independent of the DFC design (see [2]) The secret key K is first turned into a 1024 bit Expanded Key EK through an Expanding Function EF, i.e. EK = EF(K) The EF function performs a 4round Feistel scheme (see Feistel [5] The encryption itself performs a similar 8round Feistel scheme. Each round uses the Round Function RF. ....

DES Modes of Operation. Federal Information Processing Standard Publication 81, U. S. National Bureau of Standards, 1980.

....considerable buffering and be quite inefficient and prohibitively slow. For these reasons, the current implementation of bdes requires that k be a multiple of 8, so that an integral number of bytes will always be read from the file. Other than this change, this mode is implemented as described in [3]. A similar observation holds for the alternate CFB mode described in [3] Here, only the low 7 bits of each byte are significant, and hence the parameter k is an integer from 1 to 56 inclusive; bdes requires k to be a multiple of 7. The high order bit is retained for encryption and decryption, ....

....For these reasons, the current implementation of bdes requires that k be a multiple of 8, so that an integral number of bytes will always be read from the file. Other than this change, this mode is implemented as described in [3] A similar observation holds for the alternate CFB mode described in [3]. Here, only the low 7 bits of each byte are significant, and hence the parameter k is an integer from 1 to 56 inclusive; bdes requires k to be a multiple of 7. The high order bit is retained for encryption and decryption, but output (whether from encryption or decryption) always has the ....

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DES Modes of Operation, Federal Information Processing Standards Publication 81, National Bureau of Standards, U.S. Department of Commerce, Washington, DC (Dec. 1980).

....is to perform a self test between key searches and replace any faulty cards. There is no need to do testing during key searches. 5 8. Modes of DES Thus far we have concentrated on attacking DES when it is used in the electronic codebook (ECB) mode. However, there are other standard modes of DES [5]. All of the 64 bit modes can be attacked using the same machine design (this is demonstrated below) To support modes which produce less than 64 bits of ciphertext at a time requires modifications to the chip design. The modes of DES are shown in the following figure. In all cases a 56 bit key ....

"DES Modes of Operation", National Bureau of Standards (U.S.), Federal Information Processing Standards Publication (FIPS PUB) 81, National Technical Information Service, Springfield VA, 1981.

....to identify particular conversations; how this can be done is sketched in Section 6. We conclude with a discussion of possible defenses (Section 7) and a set of recommendations (Section 9) 2. Properties of Encryption Modes Our primary focus here is DES used in cipher block chaining mode (CBC) [26]. For this form of attack, stream ciphers are essentially equivalent to a CBC mode block ci 1 These RFCs are obsolete, but at press time have not yet been replaced by newer versions. pher where the initialization vector is known; this has some minor implications for the single packet attack. ....

....of plaintext P i using key K. The corresponding decryption is written P i = K Gamma1 [C i ] The symbol Phi denotes bitwise exclusive OR. If a number is written with a subscript, that subscript denotes the base; unsubscripted numbers are in base 10. 2.2. Cipher Block Chaining CBC encryption [26] operates by encrypting the exclusive OR of each plaintext block and the previous ciphertext block: C i = K[P i Phi C i Gamma1 ] To encrypt the first plaintext block, C 0 is set to the initialization vector (IV) IVs may be agreed upon in advance, transmitted encrypted, or transmitted in the ....

NBS. DES modes of operation, December 1980. Federal Information Processing Standards Publication 81.

....to show how much probable plaintext is available. We also show how traffic analysis is a powerful aid to the cryptanalyst. We conclude by outlining some likely changes to the underlying protocols that may strengthen them against these attacks. 1. Introduction DES, the Data Encryption Standard [25], is a strong cipher; however, its key length is too short to provide much security against a well financed attacker [14] More recently, designs have been published for machines that can exhaustively search the key space in a short time for a comparatively modest investment [34] Most such ....

NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....controlled, and effectively client only this is not an issue. A variety of cryptographic algorithms are defined [9, 8] for our prototype, we have implemented just one, an authentication only mechanism using MD5 [12] and a shared secret key. Future versions will likely include DES [11] and triple DES [7] 3 Implementation Details We implemented our IPSEC module as a Terminate and Stay Resident (TSR) module. Such programs are not deleted from main memory when they exit; instead, the memory area remains allocated and the contents undisturbed. The module is purely a packet ....

NBS. Data encryption standard, January 1977. Federal Information Processing Standards Publication 46.

....results from the encryption of plaintext P i using key K. The corresponding decryption is written P i = K Gamma1 [C i ] The symbol Phi denotes bitwise exclusiveOR. In showing transforms, the subscript K in ESPK denotes ESP encryption using key K . 2. 2 Cipher Block Chaining CBC encryption [NBS80] operates by encrypting the exclusive OR of each plaintext block and the previous ciphertext block: C i = K[P i Phi C i Gamma1 ] To encrypt the first plaintext block, C 0 is set to the initializaton vector (IV) IVs may be agreed upon in advance, transmitted encrypted, or transmitted in the ....

NBS. DES modes of operation, December 1980. Federal Information Processing Standards Publication 81.

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DES Modes of Operation. Federal Information Processing Standards Publication 81, December, 1980.

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"DES Modes of Operation", Federal Information Processing Standards Publication 81, National Institute of Standards and Technology, December 1980.

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DES Modes of Operation, Federal Information Processing Standards Publication 81, December 1980.

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"DES Modes of Operation", Federal Information Processing Standards Publication 81, National Institute of Standards and Technology, December 1980

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DES modes of operation, 1980. Federal Information Processing Standards Publication 81.

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DES Modes of Operation. Federal Information Processing Standard Publication 81, U. S. National Bureau of Standards, 1980.

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