I need a regex for android signature hash which is used in azure in a field presented on picture.
I used something like that:
"^(?=.{28}$)(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$"
It's matching words base64-encoded with 28 characters words but it will also match e.g. platformAndroidSignatureHash which azure decline (presented on a picture).
WORKING EXAMPLE:
get familiar with base64 encoding, especially read about padding, but in short: your "faked" String should probably ends with = or ==. you can't use regexp in here, as you should do some bitwise math, as every base64 digit needs 6 bits, in the meanwhile common usage (e.g. printing on screen) would use 8 bits per digit. you have to calculate/respect this padding. more info in THIS topic (read ALL answers and comments, accepted one isn't reliable!)
It matches platformAndroidSignatureHash because the last part with the equals signs is optional.
You could rewrite the pattern as
^(?=.{28}$)(?:[A-Za-z0-9+/]{4})+[A-Za-z0-9+/]{2,3}==?$
The pattern matches;
^ Start of string(?=.{28}$) Positive lookahead, assert 28 characters(?:[A-Za-z0-9+/]{4})+ Repeat 1+ times 4 chars of the listed in the character class[A-Za-z0-9+/]{2,3} Repeat 2-3 times matching one of the listed chars==? Match either = or ==$ End of string