Specifications of the front hub:
Brand: Shimano
Model: DH-1N70 6V-1.5W Dynamo
Color: Silver
Number of spoke holes: 32GTS
Type of brake: Rim brake
Type of axle: Drop axle
Axle included: Yes, quick release
Type of bearings: Ball bearings
Average weight (GR): 427
Intended use: MTB - Tour

Data for spoke length calculations using the Sapim spoke size calculator:
Total length of the hub (MM): 100
Non-gear side (MM): 20
Gear side (MM): 20
Hub diameter non-gear side (MM): 57
Hub diameter gear side (MM): 57

Link to spoke calculator: www.sapim.be/spoke-calculator