Squeezing

As explained in Real-World Cryptography

Squeezing is the sponge-construction phase in which output blocks are repeatedly read from the rate portion of the state.

Squeezing is the output phase of a sponge construction. After input is absorbed, the state is permuted and output blocks are read from its rate portion; the capacity remains untouched. section 2.5.2

A longer digest follows a simple repeating pattern:

• Permute the current state. section 2.5.2
• Read as much output as needed from the rate. section 2.5.2
• Repeat the permutation-and-read cycle for more output. section 2.5.2

Producing a longer digest

Once absorbing finishes, read one rate-sized block, permute the state again, and read the next block. Continue until the requested digest length is reached. section 2.5.2

Figure 2.16 To obtain a digest with the sponge construction, one iteratively permutes the state and retrieves as much rate (the upper part of the state) as needed.

Shows squeezing as repeated state permutations followed by retrieving successive portions of the rate. section 2.5.2

How Real-World Cryptography covers it

How deep it goes

Explains repeated permutation and rate reads, while omitting detailed padding treatment.

Examples

Uses a figure showing repeated permutation and retrieval of rate portions to obtain a digest.

What it assumes

Assumes familiarity with sponge state, rate, capacity, permutation, and the preceding absorbing phase.

What you can do after

Evaluate/understand how sponge constructions produce digests of the requested length.

How it connects

Connects squeezing to sponge construction, absorbing, rate, capacity, permutation, SHA-3, and hash functions.

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This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.