Base64 java string with . decode in c#

Question

I have the following string from the client - which is encoded and signed by a certificate based off of a java based SSO 3rd party component

"eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE0NTIwNTE4NTEsImlhdCI6MTQ1MjA1MTc5MSwiaXNzIjoiaHR0cHM6Ly9vYXV0aC9hcGkvb3BlbmlkL3YxL3Rva2VuIiwiYXVkIjoiZWE2NjExNjctYTRiMC00ZDQ4LWIwZTEtNWRjOTMwMzk5MDgzIiwic3ViIjoiMWQ1ZmIwYjctN2NjMy00MjRkLTg1M2QtMWE5YWNjMzg2YTM5IiwiYXRfaGFzaCI6IkF6dnktNUJoR2NBN0E2UjJqMkEwYWciLCJjX2hhc2giOiJ5dzF0NnpNcVlTbE5ITTNCQmJyemVnIn0.R6x1Hz23eaHr8H2uZSwqRa5MUYTibGl8ymSmh-t7Giep1JaQYVMoAKRonj7dWYnqrg7owEI6rgoYiHGKotiD-TKhNPGCaE3MCVCw0gtLZJ1lLq5b8ZMfInlBTcwgXVvK54ENJ04jYR04pIR6Lxb4vyk1MHEc_vHWBMtJKoQrPhFsOZh99Tq-L5aKEmUA-ygnK4ai_GCeI7Yy4aS6Al4Oa1O3E5DPQMTzd-ZZ_suM-3biHblPa-9oxrPfrwhMDyrYTpAr4yhvYHSVcXotul9AHdIkF7kDDIYo9ABQ6UJgOChGgfEPVZ3iOerPHoy8hSrkl5jgFW3w1to6k5DWBbHs9Q"

For java to c# base64 conversions, I know that the '-' needs to be replaced with '+' and '_' needs to be replaced with '/', plus the additional padding if required using '=' at the end of the string to make it the correct length for decoding -

the decoding can be done at : http://ostermiller.org/calc/encode.html and http://www.motobit.com/util/base64-decoder-encoder.asp?charset=utf-8&acharset=

using UTF-8 Encoding

Decoded String:

{"alg":"RS256","typ":"JWT"}{"exp":1452051851,"iat":1452051791,"iss":"https://oauth/api/openid/v1/token","aud":"ea661167-a4b0-4d48-b0e1-5dc930399083","sub":"1d5fb0b7-7cc3-424d-853d-1a9acc386a39","at_hash":"Azvy-5BhGcA7A6R2j2A0ag","c_hash":"yw1t6zMqYSlNHM3BBbrzeg"}�G�m�hz�k�K
�k�a8�_2�)����z�Ii2�
F���՘�����#�ࡈ��-�4ʄ��   �70%B�H--�u���o�L|��70�uo+�4�8��t����[������r���I*�+>l9�}�:�墄�@2�r�j!�x��ˆ��    x9�N�NC=��Y��7n!۔����~�!0<�a:@������U����}wH�^�2��C�    ����=Vw���<z2���^c�U��[h�NCXǳ�

From the decoded as can be seen - I need to extract the "sub" value - the rest can stay as garbage as it doesn't need to be decoded

Problem: the problem is the encoded string has a "." in it. What do i replace the "." with in C# ? I have tried replacing it with + and / which are the only 2 other no character values but it ruins the encoding and I can't get "sub"

Suggestions on what to do with the "." in the encoded base64 ?

shmosel · Accepted Answer · 2016-01-06 06:34:32Z

4

The . is not part of the base 64 encoding, it's just a separator between discrete encoded items.

eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9

decodes to

{"alg":"RS256","typ":"JWT"}

and

eyJleHAiOjE0NTIwNTE4NTEsImlhdCI6MTQ1MjA1MTc5MSwiaXNzIjoiaHR0cHM6Ly9vYXV0aC9hcGkvb3BlbmlkL3YxL3Rva2VuIiwiYXVkIjoiZWE2NjExNjctYTRiMC00ZDQ4LWIwZTEtNWRjOTMwMzk5MDgzIiwic3ViIjoiMWQ1ZmIwYjctN2NjMy00MjRkLTg1M2QtMWE5YWNjMzg2YTM5IiwiYXRfaGFzaCI6IkF6dnktNUJoR2NBN0E2UjJqMkEwYWciLCJjX2hhc2giOiJ5dzF0NnpNcVlTbE5ITTNCQmJyemVnIn0

decodes to

{"exp":1452051851,"iat":1452051791,"iss":"https://oauth/api/openid/v1/token","aud":"ea661167-a4b0-4d48-b0e1-5dc930399083","sub":"1d5fb0b7-7cc3-424d-853d-1a9acc386a39","at_hash":"Azvy-5BhGcA7A6R2j2A0ag","c_hash":"yw1t6zMqYSlNHM3BBbrzeg"}

answered Jan 6, 2016 at 6:34

shmosel

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1 Comment

Danish Over a year ago

Wow, thanks! - it worked, I should have tested that before

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