> For the complete documentation index, see [llms.txt](https://www.ctfrecipes.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://www.ctfrecipes.com/cryptography/general-knowledge/padding.md).

# Padding

Padding is a technique used in cryptography to ensure that messages or data are a fixed length, even if the original message or data is shorter than that length.

This is often necessary when using block ciphers like [AES](/cryptography/symmetric-cryptography/aes.md), which require input data to be a fixed size. Padding involves adding extra bits or bytes to the end of the message or data so that it meets the required length.

The most common padding schemes is PKCS#7 which add bytes containing the number of padding bytes to the end of the message.

Padding is important for maintaining the security and integrity of encrypted messages, as it helps prevent attackers from gaining information about the length of the original message or data.


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