Intercepted Channel

You've been sniffing traffic between Alice and Bob
Sadly for them, they picked their prime a little small.
p = 15487151
g = 5
A = 3618127
B = 6816269
The shared secret was converted to bytes
(big-endian) and used as a repeating XOR keystream over the
plaintext flag.
ciphertext (hex):
ebb4b6d8b2aadaa78cfc80b4ccf7facbb4fcdcf590c4f6a8f7f7bcf7a8ff
dc99b698b3bdf7a0bd99f5a1cc99b899b2a7f7f3a29caaa3f7b6bd99abfc
dbbb