How to decode Playfair when only a small part of key is available? What is the plain text for this message? Can someone explain how to recover the plain text for this message? Is there a program that I can download and execute on my PC to test possible keys in bulk to solve the following problem?
The cypher used is Playfair.
The partial key as a word is: ?A?D????BCG??KLNQ???V???Z
.
The partial key as a 5x5 table is:
? A ? D ?
? ? ? B C
G ? ? K L
N Q ? ? ?
V ? ? ? Z
Note that the symbol "?" indicates an unknown letter. The plain text is supposed to be in English or Portuguese. Only one of these following 3 texts is encoded by the Playfair cypher, but I don't know which.
TXT1
WL_SWVJDTA_GSFSSL_SKKGJAZVWVJ_GEMWHUG_FSFS_WSWTW_SSG_SHWGWID_F_WELAWKS-_SWFKWGFELN__OZSE.ESEV_SA,AFUEAW_DWID_WEYFGSEGSMK_VAWW_XUDSKMJV_J,AL,FI_LVF_MWSLN__GF__OZHFFL_FKK_GAWLSGFWX__WGJ_S_L_GWKJSE_MYHKGWSD_AKTF.WGLDFVASLL_FKWUA_FW_LMUGSKGAF_GAWH_LKLSGGGIGSL_GU_F_WLJMFXSFJ_WNNGUBF__YFWVWMS__F,SWJ_WA_K_GGLSFKWAVAA_SVFYJSGWJE_G_NLU_F_GLSWWLJJ,M_JAUEWWLMJLSSLXDGUVFSW_GSKEWAMFG_FAUSL_F_SSKVMLX__JKS_JNSNVVEYSDJHM_AGUEWSWWWLMFJ_AJLS__SGYFGWF_WES-_DWX
TXT2
SNPQUNBFMIENSKVNSXPQAZMEFONUGSNFRHOEKHBSQRQKRHUPXOUOTULAADZAMARNQEQUSCCORLPQLMTUDECUGXACQKCZKUSIDQOLVFRHEHUCULMIENSKVNKSQRTULAADUDQUHOKUDSERLGPAMACKOCTUQRUBPSZPQUSMQPULMIENSKVNPZPUQKAZAMKEXIMXNDAXACCNIUNEACMEFONUACUMPQUSSLUDQRTPUCAQKGDUIKTUCLGQEIPIZXKGKCDUHRQTMPMBDQSMQPGCAMRHPOXOTNRLOQABNLEPZPIEOFPUUKPISXSKMUDASKISWESKPSPQPTDQQCEHOKQOTUACAFPELMSKPSZAUPPESDPXACMECOROTVRLEHUCVNOUPQEAOQXIPQXBKGOCRHLDMQPSQKSXGSFMPEKMUCSMQCUPXDBPSXMEZPBWCDMPCAKSRETFACPOBDMPMBOHQTQBPOBCNTGSOUQOEDDNSMQPTPEPGKZPMCMAOEXMMLDUEHSIAOBUGSUDGKQOPYPQMLVNKSNXSXSMSPRNQEQUSCAFERSKREGKYDGSMEIZHEMDHRSKPSXHQKUCOEGSHKTPNTQBWDTPEROEOCLMAOBQUPMQSDCMGSHNQEQUSCRMMIQKCUDRSDMEIOCOMFHOHCPOGKYDGSUDIUSNPQUNBFMIENSKVNCAUORHRLNOPQTULAMEFOUCUDTUERGBMARSTCKSQOTPEHIPMHQKIXCAUORHRLSDMEQUMAUCUCBUMASGMUPQOKQUACMESVUPBUQMAUSLCABYMIDHPAHRBULMEHSNPQUNBFMIENUDMQMPMWCAEHXACHEOOVEGLMDQSMQTRHPOGKYD
TXT3
VBRCTB%RS1W2G_0CBKDAPQBG___GXGW,O_QCWEF2GQDGA9QG-NDRY__1U-BWCT__YRKKTYXCKBZAB_HJVG_BXY_YDUR_B39_0JS2QG-_AD__TGVKHBD__GCBDT__0KBJD_.BDYG_CD2R0Y1H_DYJGUKWJKKB,C_BHWOB_NCODXZKDG__ZB__S2_20BDECTYDDKCYY_HY5UDY_GKOT1W_CC2
_CKDPQ_0G%X9GDTKNJFJ_CC_V_TC_B_BâUKTGKXTBFAP5BK2G30T_,_-BDURGBB_DDH,N0YB_BYGBK8_A__0
SB-CD_S2J.T_CBUJU_W_UDJVBUKYDUTY€YTYCJXHC_AD0C_0K_
K2_EYGG_CCVWGBVB_K%VWCMDDG__CTOY1CNDSBYA30__WDBJC,QHYGYG_YKYN_BCKO™VUKC.X