Information and network security 29 international data encryption algorithm
The International Data Encryption Algorithm (IDEA) is a block cipher that operates on 64-bit blocks using a 128-bit key to provide high-level security through complex transformations. It generates 52 16-bit key sub-blocks from a 128-bit key and employs a series of identical encryption rounds followed by an output transformation, making it suitable for various applications such as financial services and data encryption. IDEA is known for its robust security and efficiency in both hardware and software implementations.
Information and network security 29 international data encryption algorithm
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Information and NetworkSecurity:29 International Data Encryption Algorithm Prof Neeraj Bhargava Vaibhav Khanna Department of Computer Science School of Engineering and Systems Sciences Maharshi Dayanand Saraswati University Ajmer
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International Data EncryptionAlgorithm • IDEA. Designed for software implementation • Encryption and Decryption are identical as in DES [KPS Fig 3-18]
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International Data EncryptionAlgorithm (contd.) • 128-bit key is converted to 52 16-bit keys • Inverse of the encryption key is used for decryption in the reverse order • Has patent protection
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• International DataEncryption Algorithm is one of the ciphers which encrypt the text into an unreadable format and makes it secured in order to send it over to internet. • The IDEA encryption algorithm provides high level security not based keeping the algorithm a secret, but rather upon ignorance of the secret key.
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Concept of IDEA •IDEA operates on 64-bit blocks using a 128- bit key, and consists of a series of eight identical transformations (a round) and an • output transformation (the half-round). • IDEA derives much of its security by interleaving operations from different groups — modular addition and multiplication, and bitwise • eXclusive OR (XOR) — which are algebraically "incompatible" in some sense. • In more detail, these operators, which all deal with 16-bit quantities, are: • Bitwise eXclusive OR • Addition module 216 bit encryption • Multiplication module • After the eight rounds comes a final half round, for the output.
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Structure of IDEA •XOR is used for both subtraction and ad round function. • To work with 16 bit words (meaning four inputs instead of two for the 64 bit block size), IDEA uses the Lai-Massey scheme twice in parallel, with the two parallel round functions being interwoven with each other. • To ensure sufficient diffusion, two of the sub-blocks are swapped after each round.
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IDEA Key Generation •The 64-bit plaintext block is partitioned into four 16-bit sub-blocks, since all the algebraic operations used in the encryption process operate on 16-bit numbers. • Another process produces for each of the encryption rounds,six 16- bit key subblocks from the 128-bit key. • Since a further four 16-bit key-sub- blocks are required for the subsequent output transformation, a total of 52 (= 8 x 6 + 4) different 16-bit sub-blocks have to be generated from the 128-bit key.
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IDEA Key Generation •The 52 16-bit key sub-blocks which are generated from the 128-bit key are produced as follows: • First, the 128-bit key is partitioned into eight 16-bit sub-blocks which are then directly used as the first eight key subblocks. • The 128-bit key is then cyclically shifted to the left by 25 positions, after which the resulting 128-bit block is again partitioned into eight 16-bit sub-blocks to be directly used as the next eight key sub-blocks. • The cyclic shift procedure described above is repeated until all of the required 52 16-bit key sub blocks have been generated
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Encryption • The processconsists of eight identical encryption steps (known as encryption rounds) followed by an output transformation. • The structure of the first round is shown in detail in figure next • The first four 16-bit key sub-blocks are combined with two of the 16-bit plaintext blocks using addition modulo 216, and with the other two plaintext blocks using multiplication modulo 216
Encryption • At theend of the first encryption round four 16-bit values are produced which are used as input to the second encryption round • The process is repeated in each of the subsequent 7 encryption rounds • The four 16-bit values produced at the end of the 8th encryption round are combined with the last four of the 52 key sub-blocks using addition modulo 216 and multiplication modulo 216 + 1 to form the resulting four 16bit ciphertext blocks
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Decryption • The computationalprocess used for decryption of the cipher text is essentially the same as that used for encryption of the plaintext. • The only difference compared with encryption is that during decryption, different 16-bit key sub-blocks are generated. • More precisely, each of the 52 16-bit key sub- blocks used for decryption is the inverse of the key sub-block used during encryption in respect of the applied algebraic group operation. • Additionally, the key sub-blocks must be used in the reverse order during decryption in order to reverse the encryption process
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Applications of IDEA •Hundreds of IDEA-based security solutions available in many market areas, ranging from Financial Services, and Broadcasting to Government. • IDEA is the name of a proven, secure, and universally applicable block encryption algorithm, which permits effective protection of transmitted and stored data against unauthorized access by third parties. • The fundamental criteria for the development of IDEA were highest security requirements along with easy hardware and software implementation for fast execution.
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Applications of IDEA •The IDEA algorithm can easily be embedded in any encryption software. Data encryption can be used to protect data transmission and storage. Typical fields are: • Audio and video data for cable TV, pay TV, video conferencing, distance learning, business TV, VoIP • Sensitive financial and commercial data • Email via public networks • Transmission links via modem, router or • ATM link, GSM technology • Smart cards
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• The fundamentalcriteria for the development of IDEA were military strength for all security requirements and easy hardware and software implementation. • The algorithm is used worldwide in various banking and industry applications. • They predestine the algorithm for use in a great number of commercial applications
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Assignment • Explain theworking and application of International Data Encryption Algorithm IDEA.