Unknown method problem

38° 53′ 42″ N, 77° 02′ 12″ W

February 11, 1923

My dear husband,

The BOI gave me encrypted secret messages.
I am in charge of deciphering them. I have one or two ideas,
but I would like to have your opinion. Unfortunately, the BOI
did not provide me any information,

With love, Elizabeth

NR001 0950Z KKPIN BDJDM AEWUS XWYSC YDWIT WVIFJ DGQYG ALAZK

YXPES BGNXL CYDBX HVNDJ HMRVE QGKWK OBBLR DYCSR ZFKNG FVMIM

TOTWW JDBOG EPGZW FAMVC LBGVY CTJGC FWAQQ YIIGY PCFWD WDCEA

QKWUT XRKRF YDWIT KKPIN

NR002 1010Z KKEIN DZIRS ZPCXL DGDYJ AQXWV EJGJU ZHQMB CYECT

MDFHK UWLNJ VBVRW EBMLF XDGHC IBMGH BCTPR SJSGW MUEHN WINGD

YWGNN KDJBP VBUDK YEBKG QZTSD XCYBH CMBRS BICVB YWYIU GYWFD

WICUB ZZWBU TLAAV XYOYU RSAPB HRGRO GYFHJ EMQUQ UEVJL XBDLP

CDLAE JKDDG HXMZZ KKEIN

NR003 1045Z KKZEN QUSCT DTNVD BAVRW XAXAL QGJAM YRUFE JQFVU

FNMDE LXSCB XORZC YYUQV CPGUC SQVVR JKQDU USPNO VYBRY QYIHL

OWQSV TUCDA GKLAA ERCDN WTYJG HDPRK VIAVH QAMXP OMZCO NNPSS

FLONQ ECUEK FGMMF GWHRK QNSCT COACG ETUSW KTGXX AQXHR EYZUI

AIGQS PYQVJ TLXVC NSPWH WYOXM KKZEN

NR004 1111Z KKHEV BBWHM PFAZV KDMWO PWTQA EOYJD WYWRE IQWOG

PRNSR WEQBD DQSET CDTWV UMOMN HGFGY SHLQV OBJVY GLKUV WREHY

YQUMN ZHFCT TKPAE LTMFK XAHOX IIVCU UMWCA IPAOZ JSQZC UCQSM

EQUHM YHRAR CNYUW QELHL FCVFR OUMCJ EYTSV FCNRS OZHGM PUEJW

LJRYY QUYDA IBSLI OBCRY YUTFQ AVBLB ODKYA XMACF PWWCE KTZCT

VMANL SSVXG VYHOO OKREC EYMQU SVWZM VSMOI WGWMW TNXXX KKHEV

NR005 1130Z KKGIN HKCZH AUNON BYJDT LCTTB WVSZO XAYHR OEZBJ

IHOUM QNOUE STTCY OGYBI YGRCG NZTBT GACTV GLDYI BPEGK FQHNF

BMGDD JUTLJ UEQIH SBRBU RDWEU XFMGH JJBAN WRGTG YSNGL LBLQD

BXMCT JHGMO USUTV IJDBB LFSFX FRVFD CLLJI ZLDUK YTWLK EIXHD

XBRYW DZZZZ KKGIN

NR006 1155Z KKGEV NGUPK JOCVK DMAAO YKYZU EETBB XCYVU KOEHV

RGENC XMTEZ CDLTS CODEA BLYIH FEPFQ MOOXS UQIHY GNXBW SMOYX

RGPGU MEVFO DBJDY KUXYI CLICY SUGHN VRYOB FSWTC GTWCC CWPFF

CWHGY GYSHX JVAMA YATAM VSAHB KUODW YOAKA YLTHN IJKYA UJOFR

DXQYH ZYSUV HQFNW BEUCD NUTBW IWKQM ZEFJM BQCNG WHRCY DDMVS

AMAKZ KKGEV

NR007 1212Z KKRIV XPYYH BYMQH SDNYU KZBUJ CTADU NHEQA NSQSR

RWIGY MAMHU XOBFG WTVQJ YQWDK GJWOI YOKNT RHHBE IWBBP PDHKW

UUKRT YPDUD VOYCK FWZLQ XBCAB YXNLF STIEB WHRBX DLJEO VXGIT

HCSXJ MQHYO KLKRU FFUWN QFXZG RKCBG LGBUL GBYWR MKJLL WYYBI

CTWRC AHGBG TPBNU IACEZ OUCWZ JRQWN GQJDL OLCFJ GMKZG SMUWW

LGLHB WVFQM SZICG GYUJU BEVND VQJIS FWTNG QSLBE HDFBK UBGGT

BUYST BWAQQ JLITL CCFJR UDDLL EDMEZ HSWHK TJXGY KKRIV

NR008 1222Z KKQEN JBWON VOJZX RBWMG FISFU GVCUW OOEYO RFCGG

GYYYV FSVGI TLLSU XWHTM WPHEL BAYFY FAAWJ MVPZY NOUHU MOQSR

QOXYB JJOAX FPOVZ ANXSC BQSNZ AHEYI BWMG KKQEN

NR009 1235Z KKAIN MKBZY GUTDW EUXMZ OCEWA EBWUS XWCEE QYZOS

BHGWL MOCTK YUECY ZJPWC LNXTB RBORU PWIDZ ZAGCT AGKFW AQQYM

IJZUR CRFNG FVMNU JUIYR JBKYX FKSZU HXZPZ LBWAN RBOUD WKUEN

MPDDW DJBBU ZJUAM ADCLP YTWZZ KKAIN

NR010 1255Z KKXIN QTMGW AKFYH DSHVR ABRGK DVMOC NKRJU NUUYK

JKFKH GAVDY LPSAM NOJSM EWRCY HCPSD NOHQD JJXJU TLCFT EWZSI

SMGBF SDRHQ ONNUI PLZOF GQJFG BNYHK CBTHX XFUCJ IGBJC LWJII

SFYNR PSEQI FBEOT HJKAC XODJN FECBA GTSLW ZRBEO THJYP IWVGT

BKZBO GXLQI FHLNV IJLJF ZQWXG TWZFF FQRLS TGCLV DZLYJ ALTOR

RYTWB KNUUT NWLPA BWYTC DMUEX UTVBK ZNYJI ILYLB XHAWD XWTAQ

CQDJZ KKXIN