[dart-misc] crypto chunked hash

[Istvan Soos]

Hi,

I find the crypto package a bit confusing wrt/ how to calculate sha1 hash
of a big file. Does the team have an example on how they suggest doing that?

Setting the result object on the startChunkedConversion() call is not
really intuitive, and as there seems to be a pending breaking change
anyway, I'd suggest a different route:

- Move sha1 and similar variables into functions that takes a List<int>
and return a hash. Similar to the current convert() method, they don't
store or manipulate internal state, they may not be on the class.
- Make the Sha1Hash class implement the Sink or even the
ByteConversionSink interface, and on closing, calculate the digest.

Best regards,
Istvan

['Kevin Moore' via Dart Misc]

See https://github.com/dart-lang/crypto/blob/master/example/hash.dart

This will make sure you don't load the entire file into memory. It streams
into the "hasher" and you get a result when you hit the end.

Let us know if you have other issues.

Post by Istvan Soos
Hi,
I find the crypto package a bit confusing wrt/ how to calculate sha1 hash
of a big file. Does the team have an example on how they suggest doing that?
Setting the result object on the startChunkedConversion() call is not
really intuitive, and as there seems to be a pending breaking change
- Move sha1 and similar variables into functions that takes a
List<int> and return a hash. Similar to the current convert() method, they
don't store or manipulate internal state, they may not be on the class.
- Make the Sha1Hash class implement the Sink or even the
ByteConversionSink interface, and on closing, calculate the digest.
Best regards,
Istvan

[Istvan Soos]

Thanks Kevin,

That is neat, it would be worth to put the bind part of that example
into the readme.

Thanks,
Istvan


On Thu, Sep 8, 2016 at 7:12 PM, 'Kevin Moore' via Dart Misc

Post by 'Kevin Moore' via Dart Misc
See https://github.com/dart-lang/crypto/blob/master/example/hash.dart
This will make sure you don't load the entire file into memory. It streams
into the "hasher" and you get a result when you hit the end.
Let us know if you have other issues.

Post by Istvan Soos
Hi,
I find the crypto package a bit confusing wrt/ how to calculate sha1 hash
of a big file. Does the team have an example on how they suggest doing that?
Setting the result object on the startChunkedConversion() call is not
really intuitive, and as there seems to be a pending breaking change anyway,
Move sha1 and similar variables into functions that takes a List<int> and
return a hash. Similar to the current convert() method, they don't store or
manipulate internal state, they may not be on the class.
Make the Sha1Hash class implement the Sink or even the ByteConversionSink
interface, and on closing, calculate the digest.
Best regards,
Istvan

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['Kevin Moore' via Dart Misc]

File an issue on the crypto repo – a great suggestion!

Post by Istvan Soos
Thanks Kevin,
That is neat, it would be worth to put the bind part of that example
into the readme.
Thanks,
Istvan
On Thu, Sep 8, 2016 at 7:12 PM, 'Kevin Moore' via Dart Misc

Post by 'Kevin Moore' via Dart Misc
See https://github.com/dart-lang/crypto/blob/master/example/hash.dart
This will make sure you don't load the entire file into memory. It

streams

Post by 'Kevin Moore' via Dart Misc
into the "hasher" and you get a result when you hit the end.
Let us know if you have other issues.

Post by Istvan Soos
Hi,
I find the crypto package a bit confusing wrt/ how to calculate sha1

hash

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
of a big file. Does the team have an example on how they suggest doing

that?

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
Setting the result object on the startChunkedConversion() call is not
really intuitive, and as there seems to be a pending breaking change

anyway,

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
Move sha1 and similar variables into functions that takes a List<int>

and

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
return a hash. Similar to the current convert() method, they don't

store or

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
manipulate internal state, they may not be on the class.
Make the Sha1Hash class implement the Sink or even the

ByteConversionSink

Post by 'Kevin Moore' via Dart Misc

Post by Istvan Soos
interface, and on closing, calculate the digest.
Best regards,
Istvan

--
For other discussions, see https://groups.google.com/a/dartlang.org/
For HOWTO questions, visit http://stackoverflow.com/tags/dart
To file a bug report or feature request, go to

http://www.dartbug.com/new

Post by 'Kevin Moore' via Dart Misc
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