Re: [cryptopp-users] Re: Base 64 URL Decoding Wtih Base64Decoder?

[Henry Chan]

Yeah, I did try to set the 3rd parameter to false to suppress the exception.

Tho, I am having trouble to get the correct hashed string (I didn't paste
that part of the code, which depends on the decoded string); and I wonder
it has something to do with my usage of Base64Decoder, and the exception
caught my attention...

Yes, I guess I will just copy and paste the class if nothing else I can
find.

Thanks for your input :)

On Wed, Apr 4, 2018 at 2:48 PM, Jeffrey Walton  wrote:

>
>
> On Tuesday, April 3, 2018 at 11:46:00 PM UTC-4, hc12...@gmail.com wrote:
>>
>> Hi,
>>
>> I noticed that Base64URLDecoder exists but unfortunately, I am stuck with
>> 5.6.2, which doesn't have it.
>>
>
> It can be available in all versions of the library. Just copy/paste it
> from the existing sources :)
>
>
>> So I followed the recommendation on https://www.cryptopp.com/wiki/
>> Base64Decoder (Changing Alphabets section):
>>
>> // my code snippet
>> std::string decoded_key;
>>
>> const byte ALPHABET[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabc
>> defghijklmnopqrstuvwxyz0123456789-_";
>> int lookup[256];
>> CryptoPP::Base64Decoder::InitializeDecodingLookupArray(lookup,
>> ALPHABET, 64, false);
>>
>> try
>> {
>> CryptoPP::Base64Decoder* pDecoder = new
>> CryptoPP::Base64Decoder();
>> pDecoder->IsolatedInitialize(C
>> ryptoPP::MakeParameters(CryptoPP::Name::DecodingLookupArray(),(const int
>> *)lookup));
>> pDecoder->Attach(new CryptoPP::StringSink(decoded_key));
>> // Decode the key since it is base64url encoded
>> CryptoPP::StringSource src(key, true, pDecoder);
>>
>>
>> But then I got an exception:
>> AlgorithmParametersBase: parameter "DecodingLookupArray" not used
>>
>
> Not sure why you are catching the exception but...
>
> You can add false as a thid parameter to avoid the exception:
>
> MakeParameters(Name::DecodingLookupArray(),(const int *)lookup),
> false);
>
> I'm not sure what trouble you might encounter afterwards, like failure to
> change the alphabet or changing the alphabet for all decoders.
>
> In the end, I recommend the copy/paste method to get it.
>
> Jeff
>
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[cryptopp-users] Re: Base 64 URL Decoding Wtih Base64Decoder?

[Jeffrey Walton]

On Tuesday, April 3, 2018 at 11:46:00 PM UTC-4, hc12...@gmail.com wrote:
>
> Hi,
>
> I noticed that Base64URLDecoder exists but unfortunately, I am stuck with 
> 5.6.2, which doesn't have it.
>

It can be available in all versions of the library. Just copy/paste it from 
the existing sources :)
 

> So I followed the recommendation on 
> https://www.cryptopp.com/wiki/Base64Decoder (Changing Alphabets section):
>
> // my code snippet
> std::string decoded_key;
>
> const byte ALPHABET[] = 
> "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
> int lookup[256];
> CryptoPP::Base64Decoder::InitializeDecodingLookupArray(lookup, 
> ALPHABET, 64, false);
>
> try
> {
> CryptoPP::Base64Decoder* pDecoder = new 
> CryptoPP::Base64Decoder();
> 
> pDecoder->IsolatedInitialize(CryptoPP::MakeParameters(CryptoPP::Name::DecodingLookupArray(),(const
>  
> int *)lookup));
> pDecoder->Attach(new CryptoPP::StringSink(decoded_key));
> // Decode the key since it is base64url encoded
> CryptoPP::StringSource src(key, true, pDecoder);
>
>
> But then I got an exception:
> AlgorithmParametersBase: parameter "DecodingLookupArray" not used
>

Not sure why you are catching the exception but...

You can add false as a thid parameter to avoid the exception:

MakeParameters(Name::DecodingLookupArray(),(const int *)lookup), false);

I'm not sure what trouble you might encounter afterwards, like failure to 
change the alphabet or changing the alphabet for all decoders.

In the end, I recommend the copy/paste method to get it.

Jeff

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