Three codes could be found in the MUTUAL MISTRUST post on the Investigate Ingress blog.
[1] 1321011419ZD161620L14210420d18031723
[2] 6gay5ovhhc6i7t
[3] mg4a.edwgflhdvgvg
Code #1
Observations
Try to split to find a recognizable range
Code #2
Observations
Passcode format is there, remember to apply the same method to the keyword
Code #3
Observations
That “.” is a huge hint