Re: [racket-dev] hex decoding?

[David Vanderson]

Sorry it took so long, but I've submitted a pull request to make this 
function public in file/sha1:


https://github.com/plt/racket/pull/426

Let me know if I screwed up, it's my first pull request.

Thanks,
Dave

On 06/11/2013 05:11 PM, Robby Findler wrote:

Yes, I think file/sha1 is the right place.

Thanks!

Robby


On Tue, Jun 11, 2013 at 3:26 PM, David Vanderson 
mailto:david.vander...@gmail.com>> wrote:


Thank you Stephen and Tony for your examples.  I found the
following private function in db/private/mysql/connection.rkt:

(define (hex-string->bytes s)
  (define (hex-digit->int c)
(let ([c (char->integer c)])
  (cond [(<= (char->integer #\0) c (char->integer #\9))
 (- c (char->integer #\0))]
[(<= (char->integer #\a) c (char->integer #\f))
 (+ 10 (- c (char->integer #\a)))]
[(<= (char->integer #\A) c (char->integer #\F))
 (+ 10 (- c (char->integer #\A)))])))
  (unless (and (string? s) (even? (string-length s))
   (regexp-match? #rx"[0-9a-zA-Z]*" s))
(raise-type-error 'hex-string->bytes
  "string containing an even number of
hexadecimal digits" s))
  (let* ([c (quotient (string-length s) 2)]
 [b (make-bytes c)])
(for ([i (in-range c)])
  (let ([high (hex-digit->int (string-ref s (+ i i)))]
[low  (hex-digit->int (string-ref s (+ i i 1)))])
(bytes-set! b i (+ (arithmetic-shift high 4) low
b))


Can this function be exported?  I'm willing to make a patch with
docs and tests - is file/sha1 the right place?


Thanks,
Dave

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Re: [racket-dev] hex decoding?

[Robby Findler]

Yes, I think file/sha1 is the right place.

Thanks!

Robby


On Tue, Jun 11, 2013 at 3:26 PM, David Vanderson
wrote:

> Thank you Stephen and Tony for your examples.  I found the following
> private function in db/private/mysql/connection.**rkt:
>
> (define (hex-string->bytes s)
>   (define (hex-digit->int c)
> (let ([c (char->integer c)])
>   (cond [(<= (char->integer #\0) c (char->integer #\9))
>  (- c (char->integer #\0))]
> [(<= (char->integer #\a) c (char->integer #\f))
>  (+ 10 (- c (char->integer #\a)))]
> [(<= (char->integer #\A) c (char->integer #\F))
>  (+ 10 (- c (char->integer #\A)))])))
>   (unless (and (string? s) (even? (string-length s))
>(regexp-match? #rx"[0-9a-zA-Z]*" s))
> (raise-type-error 'hex-string->bytes
>   "string containing an even number of hexadecimal
> digits" s))
>   (let* ([c (quotient (string-length s) 2)]
>  [b (make-bytes c)])
> (for ([i (in-range c)])
>   (let ([high (hex-digit->int (string-ref s (+ i i)))]
> [low  (hex-digit->int (string-ref s (+ i i 1)))])
> (bytes-set! b i (+ (arithmetic-shift high 4) low
> b))
>
>
> Can this function be exported?  I'm willing to make a patch with docs and
> tests - is file/sha1 the right place?
>
>
> Thanks,
> Dave
>
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>  http://lists.racket-lang.org/**dev 
>
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Re: [racket-dev] hex decoding?

[Matthias Felleisen]

Sorry all I am saying the creator of db/private/mysql/connection.rkt didn't 
anticipate your needs and kept the function private. 

If you want to submit a pull request to move this function to db or db/base 
(including an appropriate provide), please do so. 




On Jun 11, 2013, at 4:41 PM, David Vanderson wrote:

> On 06/11/2013 04:33 PM, Matthias Felleisen wrote:
>> 
>>  db/private/mysql/connection.rkt does not export the function, otherwise you 
>> could.
> I don't understand this.  I'd like to make the function available to users 
> somewhere - are you saying that's bad?
>> 
>> 
>> On Jun 11, 2013, at 4:26 PM, David Vanderson wrote:
>> 
>>> Thank you Stephen and Tony for your examples.  I found the following 
>>> private function in db/private/mysql/connection.rkt:
>>> 
>>> (define (hex-string->bytes s)
>>>  (define (hex-digit->int c)
>>>(let ([c (char->integer c)])
>>>  (cond [(<= (char->integer #\0) c (char->integer #\9))
>>> (- c (char->integer #\0))]
>>>[(<= (char->integer #\a) c (char->integer #\f))
>>> (+ 10 (- c (char->integer #\a)))]
>>>[(<= (char->integer #\A) c (char->integer #\F))
>>> (+ 10 (- c (char->integer #\A)))])))
>>>  (unless (and (string? s) (even? (string-length s))
>>>   (regexp-match? #rx"[0-9a-zA-Z]*" s))
>>>(raise-type-error 'hex-string->bytes
>>>  "string containing an even number of hexadecimal 
>>> digits" s))
>>>  (let* ([c (quotient (string-length s) 2)]
>>> [b (make-bytes c)])
>>>(for ([i (in-range c)])
>>>  (let ([high (hex-digit->int (string-ref s (+ i i)))]
>>>[low  (hex-digit->int (string-ref s (+ i i 1)))])
>>>(bytes-set! b i (+ (arithmetic-shift high 4) low
>>>b))
>>> 
>>> 
>>> Can this function be exported?  I'm willing to make a patch with docs and 
>>> tests - is file/sha1 the right place?
>>> 
>>> Thanks,
>>> Dave
>>> 
>>> _
>>> Racket Developers list:
>>> http://lists.racket-lang.org/dev
>> 
> 


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Re: [racket-dev] hex decoding?

[David Vanderson]

On 06/11/2013 04:33 PM, Matthias Felleisen wrote:


  db/private/mysql/connection.rkt does not export the function, otherwise you 
could.
I don't understand this.  I'd like to make the function available to 
users somewhere - are you saying that's bad?



On Jun 11, 2013, at 4:26 PM, David Vanderson wrote:


Thank you Stephen and Tony for your examples.  I found the following private 
function in db/private/mysql/connection.rkt:

(define (hex-string->bytes s)
  (define (hex-digit->int c)
(let ([c (char->integer c)])
  (cond [(<= (char->integer #\0) c (char->integer #\9))
 (- c (char->integer #\0))]
[(<= (char->integer #\a) c (char->integer #\f))
 (+ 10 (- c (char->integer #\a)))]
[(<= (char->integer #\A) c (char->integer #\F))
 (+ 10 (- c (char->integer #\A)))])))
  (unless (and (string? s) (even? (string-length s))
   (regexp-match? #rx"[0-9a-zA-Z]*" s))
(raise-type-error 'hex-string->bytes
  "string containing an even number of hexadecimal digits" 
s))
  (let* ([c (quotient (string-length s) 2)]
 [b (make-bytes c)])
(for ([i (in-range c)])
  (let ([high (hex-digit->int (string-ref s (+ i i)))]
[low  (hex-digit->int (string-ref s (+ i i 1)))])
(bytes-set! b i (+ (arithmetic-shift high 4) low
b))


Can this function be exported?  I'm willing to make a patch with docs and tests 
- is file/sha1 the right place?

Thanks,
Dave

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Re: [racket-dev] hex decoding?

[Matthias Felleisen]

 db/private/mysql/connection.rkt does not export the function, otherwise you 
could. 


On Jun 11, 2013, at 4:26 PM, David Vanderson wrote:

> Thank you Stephen and Tony for your examples.  I found the following private 
> function in db/private/mysql/connection.rkt:
> 
> (define (hex-string->bytes s)
>  (define (hex-digit->int c)
>(let ([c (char->integer c)])
>  (cond [(<= (char->integer #\0) c (char->integer #\9))
> (- c (char->integer #\0))]
>[(<= (char->integer #\a) c (char->integer #\f))
> (+ 10 (- c (char->integer #\a)))]
>[(<= (char->integer #\A) c (char->integer #\F))
> (+ 10 (- c (char->integer #\A)))])))
>  (unless (and (string? s) (even? (string-length s))
>   (regexp-match? #rx"[0-9a-zA-Z]*" s))
>(raise-type-error 'hex-string->bytes
>  "string containing an even number of hexadecimal digits" 
> s))
>  (let* ([c (quotient (string-length s) 2)]
> [b (make-bytes c)])
>(for ([i (in-range c)])
>  (let ([high (hex-digit->int (string-ref s (+ i i)))]
>[low  (hex-digit->int (string-ref s (+ i i 1)))])
>(bytes-set! b i (+ (arithmetic-shift high 4) low
>b))
> 
> 
> Can this function be exported?  I'm willing to make a patch with docs and 
> tests - is file/sha1 the right place?
> 
> Thanks,
> Dave
> 
> _
> Racket Developers list:
> http://lists.racket-lang.org/dev


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Re: [racket-dev] hex decoding?

[David Vanderson]

Thank you Stephen and Tony for your examples.  I found the following 
private function in db/private/mysql/connection.rkt:


(define (hex-string->bytes s)
  (define (hex-digit->int c)
(let ([c (char->integer c)])
  (cond [(<= (char->integer #\0) c (char->integer #\9))
 (- c (char->integer #\0))]
[(<= (char->integer #\a) c (char->integer #\f))
 (+ 10 (- c (char->integer #\a)))]
[(<= (char->integer #\A) c (char->integer #\F))
 (+ 10 (- c (char->integer #\A)))])))
  (unless (and (string? s) (even? (string-length s))
   (regexp-match? #rx"[0-9a-zA-Z]*" s))
(raise-type-error 'hex-string->bytes
  "string containing an even number of hexadecimal 
digits" s))

  (let* ([c (quotient (string-length s) 2)]
 [b (make-bytes c)])
(for ([i (in-range c)])
  (let ([high (hex-digit->int (string-ref s (+ i i)))]
[low  (hex-digit->int (string-ref s (+ i i 1)))])
(bytes-set! b i (+ (arithmetic-shift high 4) low
b))


Can this function be exported?  I'm willing to make a patch with docs 
and tests - is file/sha1 the right place?


Thanks,
Dave

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 Racket Developers list:
 http://lists.racket-lang.org/dev

Re: [racket-dev] hex decoding?

[Tony Garnock-Jones]

Here's the one I've been using in racl (https://github.com/tonyg/racl,
raco pkg install racl). It ignores non-hex characters but is less
efficient than Stephen's version. Um, and it expects *bytes* as input,
not strings. I'm not sure why, actually.


(define (hex-string->bytes . strs)
  (define cleaned (bytes->string/utf-8
   (regexp-replace* #rx"[^0-9a-fA-F]+"
(apply bytes-append strs)
"")))
  (define count (/ (string-length cleaned) 2))
  (define bs (make-bytes count 0))
  (for ((i (in-range count)))
(bytes-set! bs i (string->number
  (substring cleaned (* i 2) (+ 2 (* i 2))) 16)))
  bs)



On 2013-06-09 8:14 PM, Stephen Chang wrote:
> There doesn't appear to be a library function for going the reverse
> direction but here's one way to write it up:
> 
> #lang racket
> 
> (define ASCII-ZERO (char->integer #\0))
> 
> ;; [0-9A-Fa-f] -> Number from 0 to 15
> (define (hex-char->number c)
>   (if (char-numeric? c)
>   (- (char->integer c) ASCII-ZERO)
>   (match c
> [(or #\a #\A) 10]
> [(or #\b #\B) 11]
> [(or #\c #\C) 12]
> [(or #\d #\D) 13]
> [(or #\e #\E) 14]
> [(or #\f #\F) 15]
> [_ (error 'hex-char->number "invalid hex char: ~a\n" c)])))
> 
> (define (hex-string->bytes str) (list->bytes (hex-string->bytelist str)))
> (define (hex-string->bytelist str)
>   (with-input-from-string
>str
>(thunk
> (let loop ()
>   (define c1 (read-char))
>   (define c2 (read-char))
>   (cond [(eof-object? c1) null]
> [(eof-object? c2) (list (hex-char->number c1))]
> [else (cons (+ (* (hex-char->number c1) 16)
>(hex-char->number c2))
> (loop))])
> 
> (require file/sha1)
> (hex-string->bytes (bytes->hex-string #"turtles"))
> 
> 
> Welcome to DrRacket, version 5.3.4.6 [3m].
> Language: racket [custom].
> #"turtles"
>>
> 
> On Sun, Jun 9, 2013 at 6:30 PM, David Vanderson
>  wrote:
>> I'm doing some cryptography exercises that involve a lot of hex
>> encoding/decoding.  I see there's a bytes->hex-string function in file/sha1
>> and openssl/sha1, but I can't find a decode function.
>>
>> Is a hex decode function in the distribution?
>>
>> Thanks,
>> Dave
>> _
>>  Racket Developers list:
>>  http://lists.racket-lang.org/dev
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>   http://lists.racket-lang.org/dev
> 
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Re: [racket-dev] hex decoding?

[Stephen Chang]

There doesn't appear to be a library function for going the reverse
direction but here's one way to write it up:

#lang racket

(define ASCII-ZERO (char->integer #\0))

;; [0-9A-Fa-f] -> Number from 0 to 15
(define (hex-char->number c)
  (if (char-numeric? c)
  (- (char->integer c) ASCII-ZERO)
  (match c
[(or #\a #\A) 10]
[(or #\b #\B) 11]
[(or #\c #\C) 12]
[(or #\d #\D) 13]
[(or #\e #\E) 14]
[(or #\f #\F) 15]
[_ (error 'hex-char->number "invalid hex char: ~a\n" c)])))

(define (hex-string->bytes str) (list->bytes (hex-string->bytelist str)))
(define (hex-string->bytelist str)
  (with-input-from-string
   str
   (thunk
(let loop ()
  (define c1 (read-char))
  (define c2 (read-char))
  (cond [(eof-object? c1) null]
[(eof-object? c2) (list (hex-char->number c1))]
[else (cons (+ (* (hex-char->number c1) 16)
   (hex-char->number c2))
(loop))])

(require file/sha1)
(hex-string->bytes (bytes->hex-string #"turtles"))


Welcome to DrRacket, version 5.3.4.6 [3m].
Language: racket [custom].
#"turtles"
>

On Sun, Jun 9, 2013 at 6:30 PM, David Vanderson
 wrote:
> I'm doing some cryptography exercises that involve a lot of hex
> encoding/decoding.  I see there's a bytes->hex-string function in file/sha1
> and openssl/sha1, but I can't find a decode function.
>
> Is a hex decode function in the distribution?
>
> Thanks,
> Dave
> _
>  Racket Developers list:
>  http://lists.racket-lang.org/dev
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[racket-dev] hex decoding?

[David Vanderson]

I'm doing some cryptography exercises that involve a lot of hex 
encoding/decoding.  I see there's a bytes->hex-string function in 
file/sha1 and openssl/sha1, but I can't find a decode function.


Is a hex decode function in the distribution?

Thanks,
Dave
_
 Racket Developers list:
 http://lists.racket-lang.org/dev