Glossary · Measurement and evidence
hash-prefix lookup
A private way to look something up: instead of sending the domain it wants, a client sends the first few characters of the domain's hash and receives every entry whose hash starts the same way, then picks its own out locally. The service never learns which domain was asked about.
What hash-prefix lookup means
A private way to look something up: instead of sending the domain it wants, a client sends the first few characters of the domain's hash and receives every entry whose hash starts the same way, then picks its own out locally. The service never learns which domain was asked about. It can protect the client's interest from the service; it cannot hide the request from the network in between, which encryption handles.
What hash-prefix lookup can and cannot support
| It can support | It cannot support |
|---|---|
| A private way to look something up: instead of sending the domain it wants, a client sends the first few characters of the domain's hash and receives every entry whose hash starts the same way, then picks its own out locally. | The service never learns which domain was asked about. It can protect the client's interest from the service; it cannot hide the request from the network in between, which encryption handles. |
Terms this definition uses
Definitions that name hash-prefix lookup
Related terms in Measurement and evidence
The vocabulary for saying how strongly something is known.
signed verdict · k-anonymity · publication floor · data snapshot · evidence level · false positive · denominator note · percentile rank · population baseline · cohort asymmetry · self-audit invariant · unscored measurement · dated series · change receipt · regression · finding age · graded through a wall · self-audit · placeholder in record · fetcher disagreement · own-host loop · score version · row review · double-counted defect · cosmetic row · gated row · log file analysis · AI referral attribution · finding fingerprint · finding state · headroom · fix list · render gap · lab data · Lighthouse · RUM · LCP · CLS · INP · topicality · intent coverage · canary · citation rate · presence rate · answer stability
Questions about hash-prefix lookup
What is hash-prefix lookup?
A private way to look something up: instead of sending the domain it wants, a client sends the first few characters of the domain's hash and receives every entry whose hash starts the same way, then picks its own out locally. The service never learns which domain was asked about.
What does hash-prefix lookup not show or guarantee?
The service never learns which domain was asked about. It can protect the client's interest from the service; it cannot hide the request from the network in between, which encryption handles.
Which area of the glossary does hash-prefix lookup belong to?
Measurement and evidence: The vocabulary for saying how strongly something is known.
← signed verdict · k-anonymity →
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