c2t is collection of two DOS utilities, c2t1 and c2t2, developed by Jørgen Ibsen (a.k.a. Jibz). Each converts a COM file to one whose bytes all belong to a certain set of ASCII characters, and which still has the same functionality. c2t1 has a smaller decoder, while c2t2 usually produces smaller files.
See Executable envelopes#Transfer-encoded executables for some similar utilities.
c2t1-encoded files always start with the same 58 bytes, which can be found in the source code. The first 16 are ASCII "
c2t2-encoded files always start with the same 112 bytes, which can be found in the source code. The first 16 are ASCII "