Blocks To Go …

Prof Bill Buchanan OBE
Nov 2 · 2 min read

With block encryption we take blocks of data and encrypt each block. DES, for example, uses a 64-bit block size (8 bytes) and AES uses a 128-bit block size (16 bytes). Often the data will not fill all of the blocks so we need to pack bytes into the data. We then encrypt, and then decrypt. After this we then unpad the padding bytes. Three common methods are:

  • PKCS7. This pads with the value which equals the number of padding bytes.

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Prof Bill Buchanan OBE

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Professor of Cryptography. Serial innovator. Believer in fairness, justice & freedom. EU Citizen. Auld Reekie native. Old World Breaker. New World Creator.

ASecuritySite: When Bob Met Alice

This publication brings together interesting articles related to cyber security.

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