use scrypt

[tianxiaoliang]

Follow this checklist to help us incorporate your contribution quickly and easily:

• Make sure there is a JIRA issue filed for the change (usually before you start working on it). Trivial changes like typos do not require a JIRA issue. Your pull request should address just this issue, without pulling in other changes.
• Each commit in the pull request should have a meaningful subject line and body.
• Format the pull request title like [SCB-XXX] Fixes bug in ApproximateQuantiles, where you replace SCB-XXX with the appropriate JIRA issue.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Run go build go test go fmt go vet to make sure basic checks pass. A more thorough check will be performed on your pull request automatically.
• If this contribution is large, please file an Apache Individual Contributor License Agreement.
• Never comment source code, delete it.
• UT should has "context, subject, expected result" result as test case name, when you call t.Run().

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