An toan bao mat
TANG Tdc TRUV UAN CO SA DO UEU niA TREN GAG DIGN UU THUE NGOAI
HO KIM GIAU NGUYEN HIEU MINH*
sy PHAT TRI^N NHANH CHONG CUA DIEN TOAN DAM MAY DA DAN DEN XUAT HIEN DICH VU THUE
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NGOAI CO SO DO Lieu VA DO LA GIAI PHAP TH|£T YEU D^ GIAM CHI PHI CHO CHU SO HUU DU LIEU.
DE' DAM BAO DO LIEU DUOC AN TOAN, CHU SO HUU DU LlEU THUONG MA HOA DU LIEU TRUOC KHI LUU TRU LEN DAM MAY TUY NHIEN, VlEC MA HOA TRUOC KHI LUU TRO SE TANC THOI GIAN XU LY MA/CIAI MA KHI TRUY VAN CO SO DU LIEU. VI VAY VAN DE TANC TOO BO TRUY VAN TREN DU LlEU
DA MA HOA LA RAT CAN THIET. TRONG &Al BAO NAY CHUNG TOI D§ XUAT M O T GIAI PHAP D^ NANC
CAO TOG DO TRUY VAN TREN DO LIEU MA SU DUNG TINH TOAN SONG SONG. CAC K^T QUA THUC NGHIEM CHUNG MINH HIEU QUA CUA GIAI PHAP DE XUAT
I. Gidi THIEU CHUNG
Tren the gidi, de quan ly thdng tin eua minh, hau het eae td chOe, doanh nghiep deu luu trO dO lieu dudi dang co sd dO lieu (CSDL). Dieu nay giup ngudi ehu sd hOu dO lieu (Data Owner - DO) de dang truy xuat thdng tin va ed the ehla se cho nhieu ngudi dung. Cd hai hinh thOc lUu trOCSDL la luu trO trong ndi bd td ehOc (in house database) va lUu trO true tuyen.
Vdi hinh thOe luu trO ndi bd, DO quan ly eo sd do lieu tren may ehu cua minh, khdng chia se qua mang Internet. Nhu vay, DO phai ed he thdng may ehu gdm: may tinh, he dieu hanh, he quan trj CSDL va nhan vien van hanh he thdng.
Khi nhu cau luu trO va xO ly dO lieu tang ddi hdi DO phai tdn ehi phi eho nang cap phan eOng, cap nhap ban quyen phan mem, phat trien dpi ngu nhan vien,...
Vdi hinh thOe lOu trOtrOe tuyen, DO dat may ehu
eua minh d mdi trudng mang va quan ly nd. NhOvay, ngoai chi phi nho lOu trO ndi bd, DO tdn them ehi phi thue may ehu, ddng thdi bao ve may ehu khdi cac nguy eo tan edng tren Internet.
Ngay nay, khi dien toan dam may phat trien manh me thi eae td ehOc, doanh nghiep ed them mot phOdng an tiep can mdi trong viee quan ly, khai thac CSDL, dd la djeh vu thue ngoai CSDL (Outsourced Database Service - ODBS) [1].
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Hinh 1. Mo hinh thue ngodi CSDL flJ
5 g CflNG NGH| Thdng tin vS Truyen thong j 11/2016 • Hpc vien Ky thuat Qudn 51/
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Provider - DSP) quan ly va duy tri hoat ddng CSDL cua minh. DO khai thae ed sd dO lieu thdng qua eae phoong thOc do DSP eung cap. Theo phuong an nay, DO se giam dupe ehi phi trong viee dau t u tai nguyen va nhan edng de quan ly, duy tri CSDL.
Trong nhieu trUdng hpp, CSDL ehOa nhieu dO lieu nhay cam, DO khdng mudn nhOng ngOdi khdng cap phep dope truy cap. Tuy nhien, ludn ludn ed nhOng cupc tan cdng, ed gang lay hoac pha hoai CSDL bat hpp phap. VI vay, DO can phai ed chien lOpc bao ve CSDL eua minh. Theo sd lieu eua Sach Trang ve Cdng nghe thdng tin va Truyen thdng (CNTT-TT) Viet Nam 2014, ea nude ed tren 100.000 djch vu edng true tuyen [2]. Hau het cac don vj nay deu dang lUu trO vdi khdi lOpng CSDL rat Idn va ed rat nhieu dO lieu quan trpng (thdng tin ngan hang, bi mat quan sU, an ninh qude phdng,...). Theo eae danh gia, phan Idn CSDL tai eae don vi nay deu dupe quan ly theo md hinh CSDL truyen thdng (in-house database) va mac du eae dOn vj deu quan tam den van de bao dam an toan eho CSDL nhU dung firewall, chdng ma doe, phan quyen truy cap,... nhUng trong thUe te, khi do lieu bj rd ri thi nguy eo Id Ipt thdng tin la khdng the tranh khdi (do thdng tin la ban rd). De dam bao dupe tinh bi mat eua dO lieu, cae nha nghien eOu dUa ra giai phap ma hoa dO lieu trudc khi dua len
lieu, anh hodng rat nhieu den hieu nang eua CSDL.
Viee lOa chpn co che ma hda dam bao tinh bi mat va hieu nang tinh toan la can thiet.
Oe tang tde truy van tren dO lieu ma, ehung tdi de xuat giai phap tinh toan song song. Q.Zhang va edng sO de xuat cdng cu Qseheduler [3] de truy van song song tren he thdng CSDL. Tuy nhien, giai phap nay thue hien tren CSDL rd va thue hien song song eae eau truy van eung lue truy xuat den CSDL.
Ying-Fu Huang eiJng dUa ra phUOng phap truy van song song tren dO lieu rd [4] va thue hien cae phep giao, ndi, sap xep, nhdm,... cua eae bang dO lieu.
Samraddhi Shastri dOa ra giai phap tang tde tren do lieu ma [5], tuy nhien, phuong phap nay thUe hien truy van song song tim kiem nhj phan tren dO lieu ma.
Trong pham vi bai bao nay, nhdm tae gia trlnh bay phoong phap tinh toan song song tren dO lieu ma khi truy van. Do ket qua truy van la ban ma nen de do lieu tra ve la ban rd thi may ehu DO phai giai ma tOng ban ghi CSDL. Neu sd lupng ban ghi Idn thi thdi gian tra ve ket qua truy van kha lau. Giai phap dope de xuat da giam dang ke thdi gian thue thi de giai ma cac ban ghi khi truy van eo sd dO lieu ed sd lopng ban ghi Idn.
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@ Ii. MOT SO GONG TRJNH UEN QUAN
Rat nhieu nha nghien cOu da cdng bd cae cdng trinh ve phOPng phap truy van dO lieu ma, trong dd ed the chia ra lam ba hodng chinh: 1). DiJng sieu dO lieu (metadata) hoac eau true cay (XML) lOu trO cae thdng tin phu trp de hd trp truy van tren dO lieu ma [6, 7]; 2). Dung may chu trung gian de ehuyen ddi cau truy van [8, 9]; 3). Truy van trOe tiep tren dO lieu ma (phOPng phap nay chi hd trp mdt sd dang truy van) [10-13].
Haeigumus va cdng sO eua minh da de xuat mdt giai phap thue hien truy van tren CSDL da dugc ma hoa [6]. Y tudng eua giai phap nay la dung chuong trlnh bien ddi truy van (Query Translator) de ehuyen ddi cau truy van dang rd cua ngUdi dung sang truy van dang ma. Cac dO lieu dupe ma hda trUde khi luu trO d may ehiJ eua SP. Ngoai ra, dO lieu cd them thdng tin phu trp (metadata), la eae ehi muc cho phep thue hien truy van CSDL tai may ehu eua SP ma khdng can phai giai ma. DO dung metadata de ehuyen ddi eae truy van eua Client thanh cac truy van thich hpp de thue thi tren may ehu, va Client se nhan dupe ket qua sau khi thue hien truy van dUpc tra ve tO may ehu eua SR DOa tren cae thdng tin phu trp da dope luu trO, truy van se dugc chia thanh hai phan: (1) Cac truy van d ph ia may chu (Server Site) ve
eae do lieu da dope ma hda, truy van nay dope thUc hien tai may chu eCia SP, (2) Cae truy van phia ngudi dung (Client Site), truy van nay dugc thOe hien tren may eua Client, thdng qua may cua DO va ket qua truy van sau khi dope Ipc se tra ve tO DO eho Client Tuy nhien, phoong phap nay ed nhOng nhope diem la tang ehi phi lou trO, va ehi phi de tinh toan lai sau hoat ddng cap nhat eo sd dO lieu. Cac truy van gdp (SUM, COUNT, AVERAGE...) khdng thOc hien dope
R. Brinkman dOa ra mdt phoong phap tim kiem tren dO lieu ma bang each so cac the dO lieu trong XML da dope ma hoa vdi dO lieu tren djeh vu thue ngoai [7]. Vdi phOOng phap nay, dO lieu dope chia thanh nhieu khdi va ma hoa eae khdi nay trOde khi dOa len server. DO lOu trO cac thdng tin ve ma hoa de thuc hien giai ma d qua trinh truy van ket qua.
Khi tim kiem, ehudi dO lieu can tim se dUpc ma hoa va chuyen den cho server de so sanh vdi cac the va xae djnh ra vj tri eua doan dO lieu ma hda dd. Glal doan nhan dO lieu, ket qua ma hda se dUpe giai ma doa theo eae thdng tin ma hda dope ghi nhan tai giai doan lOu trO. PhOOng phap nay chi dap Ong cac cau truy van tim kiem so trung eae the dO lieu trong XML ma khdng xO ly den ndi dung dO lieu ben trong the dd.
A. Popa va edng sotrinh bay mdt md hinh ma hoa va each thOc thOe thi truy van tren CSDL ma bang each sO dung mdt may ehu lam trung gian gpi la CryptDB proxy [8]. CryptDB proxy lOu trO khoa bi mat, lope dd CSDL, va eae Idp ma hoa hien tai eiJa mdi cdt. May chu CSDL lOu trO mdt lOpe dd an danh (ten bang va ten cdt dope thay the bang djnh danh), do lieu ngUdi dung dupe ma hda, va mdt sd bang phu trp dupe sO dung bdi CryptDB. CryptDB eung eung cap cho eae may ehu vdi mdt sd ehOe nang ngudi dung djnh nghia (UDF) cho phep eae may ehii tinh toan tren dO lieu ma vdi mdt sd phep toan nhat djnh.
Diem manh eua CryptDB la cho phep eae may ehu tinh toan tren dO lieu ma hda ma khdng can giai ma va cho ket qua eOng la gia trj ma hda. CryptDB la he thdng trung gian ed the eung cap bao mat hieu suat cao cho cae Ong dung trOe tuyen tren DBMS.
5 2 CONG NGHt Th6ng tin vi Truyen thong 111/2016
bat ky thay ddi ben trong cua may ehu DBMS va ket qua dope giai ma bdi cac user dang tin cay. Nd ed the lam viec vdi hau het cac he thdng co sd dO lieu SQL vdi chi phi rat it. De dat dope dieu nay, CryptDB to ddng thay ddi kieu ma hda dua tren khdi lopng edng viec truy van de lOa chpn nhanh chdng va dam bao du eae thao tae tren dO lieu.
CryptDB eo ban giai quyet dope van de hd trp tat ca eae loai truy van SQL tren CSDL ma hoa va dam bao tinh rieng to eua dO lieu. Ddng thdi, CryptDB ed thdi gian thOe hien vdi chi phi thap. Tuy nhien, CryptDB can mdt proxy hoan toan tin cay, nhOng day la nPi ma ketan cdng Ipi dung. Neu ketan cdng xam nhap dugc CryptDB, ehung ed the giai ma cac ban ghi CSDL, lay dugc toan bd thdng tin dO lieu. Nhu vay, van de bao mat proxy can dupe xem xet. Mat khae, CryptDB ehua hd trp het tat ea eae eau truy van dO lieu.
iii. TiNH TOAN SONG SONG KHI TRUV UAH CSDL MA
A. Mo hinh lUu triii cd sd duT lieu ma
Chu CSDL se ma hoa CSDL trUde khi luu trO d CSDL thue ngoai (Outsourced Database). De biet dugc eau true eua CSDL khi tinh toan, tai may ehu cua DO se luu trO eae ehi mue dO lieu trong mdt tap tin XML de tham ehieu den eau true bang dO lieu dOOc ma hda.
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H7mh 2. Mo hinh luu trd CSDL md
Nho vay, thay vi ten bang, ten trudng la ban rd thi DO dung ham bam de ma gia trj dd thanh ban ma.
Trong trOdng hpp nay, ngUdi tan edng va ngay ea SP
cae the nay, ehung ta ed the tao ra mdt eau true do lieu, cd the truy xuat trOc tiep hoac xay dong thanh cay tim kiem. XML dugc hd trp tren hau het cac ngdn ngO lap trinh hien nay vdi cac bd parser nho SAX, DOM hoac STAX. Cau true eua XML la dang text nen tap tin XML ed dung lOpng nhd, thdi gian truy cap nhanh. Mdi lan truy van CSDL, thay vl dung ham bam de tinh toan ten trOdng, ten bang de truy van thi may ehu DO ehi can tham ehieu ten trOdng trong tap tin XML, do dd rut ngan thdi gian rat nhieu neu thOc thi ham bam mat ma.
Vi du; Cho CSDL cd bang Nhanvien(Manv, Hoten, Ngaysinh, Gioitinh, Diachi) thi tap tin XML bieu dien nho Hinh 3:
< ? X H 1 version=°l,0' encoding='in'F-8'' standalone="no"?>
<tables>
<Mhanvien na»e=""9416Wf7e6cab8b4446ad3aa6c9cf2e5">
<Han V >U>12f8f<ft>SKeebe5a65f219f6bcKa6</Kan v>
<Hoten>cd5e78aee213699bcc»6739fa7<B2«</Hoten>
<Ngay5ir-r>eU2dS6af4be494c73c85ie788eSc6fS</Ugaysinh>
<Gioitln^>bbec2b7ea36985e3&S^&27ebc86eiec</Gioitinh>
<D2 a c h i > f 4 f ^ 3 d i e d 8 3 f 286d29See318a4ac79e</Diach i >
</Hhanvien>
</tables>
Hinh 3. Cau true tap tin XML
Khi do, bang Nhanvien se c6 cau true theo anh x a 1 - l :
Nhanvien Manv Hoten Ngaysinh Gioilinli Diadi i
941694f7e6cab8b4446ad3aa6c9cf205 bbl 2f8fdb8f600b05a65f219f6bc65a6 c45e78a08213699bcc296739fa7d32f9 0O42d56af4b0494c73c851078068c6f5 bbec2b7ea369850368a5 627ebc8601 ec f4f503dlOd83£286d298eO318a4ac796
Nhu vay, khi lOu trO CSDL tren server, thay vl luu trOten bang la Nhanvien thi DO lOu trOten bang la:
941694f7e6eab8b4446ad3aa6e9cf205.
B. Truy van cC sd duf lieu ma
Khi mudn thao tae tren dO lieu, ngudi diJng gOi yeu eau len may chu va dupe tra ve dO lieu rd. Mdt each tiep can khi truy van CSDL ma hda la tai toan bd CSDL ve may ehu DO, sau dd giai ma tOng ban ghi rdi thOc
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hien truy van. Tuy nhien phOdng phap nay tdn nhieu tai nguyen va thdi gian tinh toan. Mdt each tiep can khae la truy van eae dO lieu ed lien quan, sau dd giai ma cac ban ghi va thOe hien cae tinh toan tren ban ghi dd. Trong qua trinh truy van tren dO lieu ma phai dope tham ehieu qua bang XML de dam bao eae ban ghi tra ve la dung dan.
Cae loai truy van nho SELECT, INSERT, UPDATE, DELETE deu ed the thOe hien true tiep tren dO lieu ma, trong khi eae eau truy van gdp (truy van Idng nhau) thi can thue hien eae phep bien ddi, viet lai eau truy van. Trong pham vi bai bao nay, nhdm tae gia thOe hien eae truy van INSERT, UPDATE, DELETE;
truy van SELECT vdi cae phep toan nhO SUM, AVERAGE, MAX, MIN...
Vi du; ngudi diJng mudn cap nhap lai dja chi mdi eua nhan vien ed ma la '01'.
Cau truy van rd se la: UPDATE Nhanvien SET Diachi
= <dja chi mdi> WHERE Manv='01'.
Cau truy van tren dO lieu ma la; UPDATE t SET f5
= Ene(<dja ehi mdi>, key) WHERE f l = Ene('0T, key).
Trong dd t la dO lieu truy xuat trong file XML tOOng Ong vdi the Nhanvien, f l tuong Ong the Manv, f5 tuong Ong the dja ehi, Enc(data, key) la mdt ham ma hoa vdi khoa key dupe xac djnh trudc.
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N M p « M y ^ UPDATE 1 SETS=Enc:(«fi i$u m d ^ . km/) WHERE n=EBcnn-. ksy)O ^ d p i g
Hinh 4. Mo hinh truy vdn dOlieu
C. Tinh toan song song
Tinh toan song song la mdt qua trlnh tinh toan trong dd nhieu phep tinh dUgc thUc hien ddng thdi, hoat ddng tren nguyen tae la nhOng van de Idn deu ed the chia thanh nhieu phan nhd hon, sau dd dupe giai quyet tUPng tranh. Cd nhieu hinh thOe khae nhau eua tinh toan song song: song song cap bit, song song cap lenh, song song dO lieu va song song tae vu. Tinh toan song song dupe sO dung chu yeu
5 4 CONG NGHt Thong tin va TruySn thong 111/2016
trong ITnh vOc tinh toan hieu nang cao. NhOng nam gan day, hinh thOe tinh toan nay dope quan tam nhieu hon, do nhOng han che vat ly ngan chan viec tang hieu nang tinh toan chi bang each tang tan sd.
Vi viec tieu hao dien nang (dan den sinh nhiet) ti^
may tinh da trd thanh mdt mdi lo ngai, tfnh toan song song da trd thanh md hinh thdng trj trong linh vOc kien true may tinh, phan Idn la dOdi dang bd xCr ly da nhan.
Hinh 5. Tinh todn tuan td
Hinh 6. Tinh todn song song Cac may tinh song song cd the dugc phan loai tijy theo cap dp hd trp song song cua phan cOng, vdi nhOng chiee may tinh da nhan va da xO ly cd bd phan da xO ly trong mdt may don le, trong khi cum may tinh, xO ly song song hang loat, va dien toan lodi sO dung nhieu may tinh de xO ly eCmg mdt edng viec NhOng kien true may tinh song song ehuyen dung thinh thoang eung sOdung eae bd xO ly truyen thdng, nham tang tdc dp cho nhOng edng viee dae trung.
D. Oe xuat thuat toan tfnh toan song song khi truy van cdsddCt lieu ma
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Hinh 7. Mo hinh tinh todn song song
va viet lai eau truy van dO lieu. Sau dd, edng viec thOe hien la giai ma cac ban ghi ket qua.Trong qua trlnh giai ma eae ban ghi CSDL, neu tien hanh giai ma tuan t o vdi sd lopng ban ghi Idn thi thdi gian thOe hien kha lau. De giam thdi gian xO ly, DO ed the eho phep thOc hien viee giai ma eae ban ghi song song tren CPU hoac GPU.
Gia sO khi ngOdi diJng mudn hien thj danh sach nhan vien, hoac xO ly tinh toan tren ban rd eua dO lieu tra ve thi ngodi dung phai giai ma tOng ban ghi eua dO lieu.
Lue nay, chung ta chia nhd tap ket qua D thanh nhieu tap con va giai ma song song tren tOng tap eon (cd the ket hpp xO ly tinh toan) thi se giam dang ke thdi gian xO ly. Phoong phap xO ly song song nay ed the ap dung eho cae phep toan gdp tren SQL, eae ham SUM, AVERAGE...
Oataset 0 //Main function
D <- EssUJelSELECT f 1, f2 fn FROM t) 0 = DlwD2 w... wDn
Thread T l = new IhcefldlFl) Thread T2 = ne w Ih[ejKliF2) Thread Tn = new HjcSfldlF") R«-teMn,T2,...,Tn) Return R
//Function Fl Foreach record r in 01 r:<- Decrypt(r) Rl *- Caculate in r' Return Rl //Function F2 Foreach record r in 02 C^ Oecnfpt(r) R2 <- Caculate in f Return R2 //Function £ii Foreach record r in Dn t ^ Decryptfr) Rn *- Caculate in r"
Return Rn
la do lieu truy xuat trong file XML tOOng Ong vdi the Nhanvien, f l , f2,..., fn tOong Ong vdi eae trOdng dO lieu. Ket qua truy van tra ve la tap hpp D chOa cae ban ghi ma. Khi sd lOdng ban ghi Idn (vai trieu ban ghi), thdi gian tfnh toan la tdng thdi gian giai ma tuan t o eae ban ghi. Khi ehla nhd tap D thanh cae tap eon D l , D2,..., Dn va giai ma eae tap con nay thi thdi gian la max(TDl,TD2,...,TDn), vdiTDj la thdi gian giai ma eua tap j . Nho vay, thdi gian tinh toan giam dang ke, dieu nay ehua dupe de cap trong eae edng trlnh nghien eOu khae trUde day.
E. Ket qua thifc nghiem
De danh gia md hinh tinh toan song song khi truy van CSDL ma hoa da de xuat, ehung tdi thUc hien thO nghiem tren may tinh Core 13-1,5 GHz, 4 Gb bd nhd, choong trlnh truy van CSDL dope thOc hien vdi cae thuat toan truy xuat tuan tu, truy xuat song song 2 ludng, song song 4 ludng sO dung ngdn ngO lap trlnh C#, Visual studio 2013. Thuat toan ma hoa dOlieu la AES. He quan trj CSDL SQL Server 2012. Bang ghi ed 5 trudng dO lieu. Thdi gian thOc hien thuat toan dope tinh bang miligiay (ms).
Tnjy xu^ cO li$u ma ho6
- * — S a i g soig 2 hidng - S a i g 5 a n g 4 h j ^
Hinh 8. Thd nghiem truy vdn song song vdi 2036 bdn ghi CSDL
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-*-Songsong2luing - -Saigsong4lu6ng
2 3 4 SA lin ovc hien
Hinh 9. Thd nghiem truy vdn song song vdi 5045 bdn ghi CSDL
Tiuy xu4t dO i $ u m a hod
Tuan IV Song song 2 luAng Song song 4 luAng
2 3 4 S6Unlhucni»n
Hinh lO.Thd nghiem truy vdn song song vdi 11.000 bdn ghi CSDL
Cae ket qua thuc nghiem (Hinh 8,9,10) eho thay, khi sd lupng ban ghi eua CSDL it, thi thdi gian tinh toan tuan tuva song song ehenh lech nhau khdng nhieu. Tinh toan song song thUe sU cd y nghia khi sd lopng ban ghi Idn. Viee phan chia sd lOpng phep toan song song cUng can tinh toan, mae du chia nhieu ludng song song mang lai ket qua tdt hon, nhung trong mdt sd trUdng hpp, khi eae phep toan d mdt sd ludng thue hien xong thi se cd dp tre, lue dd se khdng ed su khae biet ve thdi gian, tham ehi se cham hon khi xO ly it ludng.
IU. KET LUAN
Viec dam bao tinh bao mat eiJa dO lieu thudng dupe giai quyet bang each ma hoa dO lieu trOdc khi lOu trOtren may ehu. Bai toan dat ra la giai quyet tdc dp xO ly khi truy van dO lieu do. Trong bai bao nay, ehung tdi de xuat giai phap tinh toan song song tren dO lieu ma. Tuy nhien, de cai thien dope tde dp khi truy van edn can nhieu giai phap hd trp, trong
dd, thuat toan ma hoa eCing la mdt yeu td lam cham qua trinh tinh toan tren dO lieu ma. Do do, can phai lua chpn eae phOPng phap ma hoa lam sao de tdi uu nhat ve tde dp xO ly. Xu hodng dung thuat toan ma hoa ddi xOng thi xO ly ma hoa - giai ma nhanh nhOng khdng tinh toan dope tren dO lieu ma. Nhu vay tdn nhieu ehi phi neu ngUdi dung mudn tinh toan. May ehu bat budc phai giai ma de dupe ban rd, tinh toan tren ban rd, rdi ma hoa lai ket qua gOi ve eho ngOdi dung. Neu dung thuat toan ma hoa ddng eau (homomorphie) thi hd trd tinh toan tren dO lieu ma nhung bu lai tdn chi phi trong viec ma hoa va giai ma. Xu hOdng dung hdn hpp cae thuat toan ma hoa, phan chia trOdng hpp truy van toong Ong vdi do lieu ma phu hpp la mdt xu hodng hien tai. ©
Tai lieu tham khao:
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5 g CflNG NGHt Thong tin vi Truyen thong 111/2016
