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corroborate (v.)[corroborate 词源字典]: 1530s, "to give (legal) confirmation to," from Latin corroboratus, past participle of corroborare "to strengthen, invigorate," from com- "together" or "thoroughly" (see com-) + roborare "to make strong," from robur, robus "strength," (see robust).

Meaning "to strengthen by evidence, to confirm" is from 1706. Sometimes in early use the word also has its literal Latin sense, especially of medicines. Related: Corroborated; corroborating; corroborative.[corroborate etymology, corroborate origin, 英语词源]
credential (n.): "that which entitles to credit," 1756, probably a back-formation from credentials. Earlier in English as an adjective, "confirming, corroborating" (late 15c.). As a verb, "provide with credentials," by 1828 (implied in dredentialed).
token (n.): Old English tacen "sign, symbol, evidence" (related to verb tæcan "show, explain, teach"), from Proto-Germanic *taiknam (cognates: Old Saxon tekan, Old Norse teikn "zodiac sign, omen, token," Old Frisian tekan, Middle Dutch teken, Dutch teken, Old High German zeihhan, German zeichen, Gothic taikn "sign, token"), from PIE root *deik- "to show" (see teach).

Meaning "coin-like piece of stamped metal" is first recorded 1590s. Older sense of "evidence" is retained in by the same token (mid-15c.), originally "introducing a corroborating circumstance" [OED].