Information and Network Security: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
International Data Encryption Algorithm • IDEA. Designed for software implementation • Encryption and Decryption are identical as in DES [KPS Fig 3-18]
International Data Encryption Algorithm (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
• International Data Encryption 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.
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.
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.
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.
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
Encryption • The process consists 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: Structure of the first round
Encryption • At the end 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
Decryption • The computational process 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
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.
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
• The fundamental criteria 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
Assignment • Explain the working and application of International Data Encryption Algorithm IDEA.

Information and network security 29 international data encryption algorithm

  • 1.
    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
  • 2.
    International Data EncryptionAlgorithm • IDEA. Designed for software implementation • Encryption and Decryption are identical as in DES [KPS Fig 3-18]
  • 3.
    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
  • 4.
    • 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.
  • 5.
    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.
  • 6.
    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.
  • 7.
    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.
  • 8.
    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
  • 9.
    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
  • 10.
    Encryption: Structure ofthe first round
  • 11.
    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
  • 12.
    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
  • 13.
    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.
  • 14.
    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
  • 15.
    • 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
  • 16.
    Assignment • Explain theworking and application of International Data Encryption Algorithm IDEA.