I devised this cipher independently, but I have no idea whether it's easy or hard because I have little knowledge of cryptography. The algorithm is simple but not trivial.
AYVEKCI0 3D3 1UDTY1NWBYFJFUJDLQOFQIDWZ0UQMVWKLUCO3GWXWO
Note that both 0s and Os are present.
Here are symbols you might think are possible in this cipher, but are not: 456789
Here is a symbol you wouldn't know is possible from the given code: ?
FYW?HIJUHZ0LPENNS0SZBF?N3DUZTECJMJVTMY03HDPJWH2Q0NZIE31SNUV YOBK MRKTBFFASDXBKLKR?FAL3PWO30IIBM HKGO PCSHD1PDYZPUIQVHHVIZYB BTHHP M IPEX2R L3Z?FAL3YH?120QD 3D3KOVTU?V2B2IBVEV 23XDSHMYUJQSV?SDMJH UNYJJUJVATFE TCX0D3KOVPY? WFSIF2LFADUYJG22S1?SWAUFEIF?ORKDNYLUX NC2MLFPN1AMBY3VG?R2LMRD1BKMJVOBXGVTN OVHIR0JBZLJSXTAXZ2XEJYJITJY AEFYCCR12REYJMOAIH2ITSC3SLVC01YMVIOFMZNNMGHEWQHLAGIOTM1QSHA1AYVE KCI0 3D3 1UDTY1NWBYFJFUJDLQOFQIDWZ0UROTVKXKG32HLPM CZDS3NRHGVCF? O2?D2IS0GPLM0KEYYSDZIYSUL3UHOGJ3GJ0KSJ?BYUFSHFNLVAL1DEKEULGPL1YH B1 XMQLKLDSL1FLKNWF3YEGXOSO1XJTX FT VOTYNZ2WDQFMH0W3L VMVVDUHFO0 MRDMCJLKWNJ?G2GG?JWLUXT3LWZTGYGB 1D 0XII3T1MQSHA1AYVEKCI0 3D3 1U DTY1NWBYFJFUJDLQOFQIDWZ0UROTVKXKG32HKWO2DVSTM MRIMQKH3O?N22YSYNQ UNUIGUD2 DE0JUHIPUAZTHMUI2PVG03QUFUYUAFU N1QG3TOYEUDW GFVMXNOXQO AFVSAV2BZ02W1NCZ3QSB 1?JCSULEQO3ETXE2IU2UYQCJQMQON31AURE32ESO3BV 0F DV TGO3P3O
Everything has been generated by computer instead of by hand, so there should be no more errors. So sorry for it being messed up at first!
2014/12/8 - More clues:
Characters are processed in groups of five.
The plaintext contains every letter of the alphabet except Q.
? immediately precedes A.
The fact of 32 possible characters requires that characters be processed in groups of 5: 2^5 characters in the alphabet, 5 characters per group.