From the OED...
The form intrust, though preferred in many recent Dicts., is now rare in actual use.
1. trans. To invest with a trust; to confide a task, an object of care to (a person, etc.); to commission or employ in a manner implying confidence. a. Const. to with inf., �for (a purpose), in (a business); also simply. Obs. or arch. exc. in Law.
a 1602 Carew Cornwall 82b, They+ were wont to be entrusted, for the Subsidiary Cohort, or band of supply. 1646 Sir T. Browne Pseud. Ep. iii. xi. 130 The Griffin+doth+well make out the properties of a Guardian, or any person entrusted. 1665 G. Havers P. della Valle's Trav. E. India 31 The last Advertisements+argue that the King still entrusts him. 1666 Pepys Diary (1879) IV. 108 The report we received from those entrusted in the fleete to inform us. 1691 in W. Perry Hist. Coll. Amer. Col. Ch. (1860) I. va. 4 The Archbishop of Canterbury+was wholly entrusted by the King and Court for all Ecclesiastical affairs. 1759 Robertson Hist. Scot. I. ii. 112 The clergy were entrusted because they alone were properly qualified for the trust. 1836 J. Grant Random Recoll. Ho. Lords xiii. 290 Earl Grey+entrusted his son-in-law in the execution of so important a task. 1885 Law Rep. Q. Bench Div. XIV. 202 The Attorney General only+was entrusted by the constitution to sue for the King.
b 1649 Milton Eikon. Wks. 1738 I. 387 The Governor besought humbly to be excus'd, till he could send notice to the Parlament who had intrusted him. a1674 Clarendon Hist. Reb. (1704) III. xii. 254 Sr Benjamin Wright; who was intrusted by them to sollicite at Madrid for their Pass.
From the dates of the quotes it would appear that this argument has been going on for some time.
There appear to be quite a few words with the in-/en- dual spelling. One thing that struck my fancy when looking up this word was the word, entuite. I was a given a roundtuit once at work, but I never thought that there would be an entuite.
