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'''bcrypt''' merupakan fungsi hashing kata sandi yang dirancang oleh dua orang peneliti keamanan komputer [https://www.provos.org/ Niels Provos] dan David Mazières, cipher [[Blowfish (penyandian)|Blowfish]] adalah dasar pembuatan bcrypt, dan disajikan di USENIX pada tahun 1999.
Fungsi bcrypt merupakan
▲'''bcrypt''' merupakan fungsi hashing kata sandi yang dirancang oleh dua orang peneliti keamanan komputer [https://www.provos.org/ Niels Provos] dan David Mazières, cipher [[Blowfish (penyandian)|Blowfish]] adalah dasar pembuatan bcrypt, dan disajikan di USENIX pada tahun 1999. <ref name="provos">{{Cite journal|last=Provos|first=Niels|last2=Mazières, David|last3=Talan Jason Sutton 2012|year=1999|title=A Future-Adaptable Password Scheme|url=http://www.usenix.org/events/usenix99/provos/provos_html/node1.html|journal=Proceedings of 1999 USENIX Annual Technical Conference|pages=81–92}}</ref> bcrypt dapat melindungi dari serangan [[Tabel pelangi|rainbow table]] dengan mengunakan [[Salt (kriptografi)|salt]], selain itu, bcrypt adalah fungsi adaptif: seiring waktu, jumlah iterasi dapat ditingkatkan untuk membuatnya lebih lambat, sehingga tetap aman terhadap serangan pencarian brute-force bahkan dengan meningkatnya daya komputasi.
bcrypt dapat diimplementasikan pada bahasa pemrograman PHP, Python, JavaScript, C, C ++, C #, Go,
▲Fungsi bcrypt merupakan algoritma hash password dasar untuk [[OpenBSD]] <ref name="original">{{Cite web|url=//cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/crypt/bcrypt.c|title=Commit of first work to repo|date=13 Feb 1997}}</ref> dan sistem lain termasuk beberapa [[distribusi Linux]] seperti SUSE Linux . <ref>{{Cite web|url=https://www.suse.com/support/security/advisories/2011_35_blowfish.html|title=SUSE Security Announcement: (SUSE-SA:2011:035)|date=23 August 2011|archive-url=https://web.archive.org/web/20160304094921/https://www.suse.com/support/security/advisories/2011_35_blowfish.html|archive-date=4 March 2016|dead-url=yes|access-date=20 August 2015|quote=SUSE's crypt() implementation supports the blowfish password hashing function (id $2a) and system logins by default also use this method.}}</ref>
== Algortima ==
<span data-segmentid="94" class="cx-segment">Algoritme bcrypt adalah hasil dari enkripsi teks ''"OrpheanBeholderScryDoubt"'' 64 kali menggunakan [[Blowfish (penyandian)|Blowfish]] .</span> <span data-segmentid="96" class="cx-segment">Dalam bcrypt fungsi biasa key setup pada Blowfish digantikan dengan fungsi expensive key setup (EksBlowfishSetup)</span>
'''Function''' bcrypt
'''Input:'''
cost: Number (4..31) log<sub>2</sub>(Iterations). e.g. 12 ==> 2<sup>12</sup> = 4,096 iterations
salt: array of Bytes (16 bytes) random salt
password: array of Bytes (1..72 bytes) UTF-8 encoded password
'''Output:'''
hash: array of Bytes (24 bytes)
//Initialize Blowfish state with expensive key setup algorithm
''state'' <- EksBlowfishSetup(''cost'', ''salt'', ''password'')
//Repeatedly encrypt the text "OrpheanBeholderScryDoubt" 64 times
''ctext'' <- ''"OrpheanBeholderScryDoubt"'' //24 bytes ==> three 64-bit blocks
'''repeat''' (64)
''ctext'' EncryptECB(''state'', ''ctext'') //encrypt using standard Blowfish in ECB mode
//24-byte <- ''ctext'' is resulting password hash
'''return''' Concatenate(''cost'', ''salt'', ''ctext'')
=== Expensive key setup ===
Algoritme bcrypt sangat bergantung pada algoritme key setup "Eksblowfish", berikut algoritmanya:
'''Function''' EksBlowfishSetup
'''Input:'''
cost: Number (4..31) log<sub>2</sub>(Iterations). e.g. 12 ==> 2<sup>12</sup> = 4,096 iterations
salt: array of Bytes (16 bytes) random salt
password: array of Bytes (1..72 bytes) UTF-8 encoded password
'''Output:'''
state: opaque BlowFish state structure
''state'' <- InitialState()
''state'' <- ExpandKey(''state'', ''salt'', ''password'')
'''repeat''' (2<sup>''cost''</sup>)
''state'' <- ExpandKey(state, 0, password)
''state'' <- ExpandKey(state, 0, salt)
'''return''' ''state''
=== Expand key ===
Berikut algoritme fungsi ExpandKey
'''Function''' ExpandKey(''state'', ''salt'', ''password'')
'''Input:'''
state: Opaque BlowFish state structure Internally contains P-array and S-box entries
salt: array of Bytes (16 bytes) random salt
password: array of Bytes (1..72 bytes) UTF-8 encoded password
'''Output:'''
state: opaque BlowFish state structure
//Mix password into the internal P-array of ''state''
'''for''' ''n'' <- 1 '''to''' 18 '''do'''
P<sub>n</sub> <- P<sub>n</sub> xor ''password''[32(n-1)..32n-1] //treat the password as cyclic
//Encrypt state using the lower 8 bytes of salt, and store the 8 byte result in P<sub>1</sub>|P<sub>2</sub>
''block'' <- Encrypt(''state'', ''salt''[0..63])
P<sub>1</sub> <- ''block''[0..31] //lower 32-bits
P<sub>2</sub> <- ''block''[32..63] //upper 32-bits
//Continue encrypting state with salt, and storing results in remaining P-array
'''for''' ''n'' <- 2 '''to''' 9 '''do'''
''block'' <- Encrypt(''state'', ''block'' '''xor''' ''salt''[64(n-1)..64n-1]) //encrypt using the current key schedule and treat the salt as cyclic
P<sub>2n-1</sub> <- ''block''[0..31] //lower 32-bits
P<sub>2n</sub> <- ''block''[32..63] //upper 32-bits
//Mix encrypted state into the internal S-boxes of ''state''
'''for''' ''i'' <- 1 '''to''' 4 '''do'''
'''for''' ''n'' <- 0 '''to''' 127 '''do'''
''block'' <- Encrypt(''state'', ''block'' '''xor''' ''salt''[64(n-1)..64n-1]) //as above
S<sub>i</sub>[2n] <- ''block''[0..31] //lower 32-bits
S<sub>i</sub>[2n+1] <- ''block''[32..63] //upper 32-bits
'''return''' ''state''
▲bcrypt dapat diimplementasikan pada bahasa pemrograman PHP, Python, JavaScript, C, C ++, C #, Go, <ref>{{Cite web|url=https://godoc.org/golang.org/x/crypto/bcrypt|title=Package bcrypt|website=godoc.org}}</ref> Java, <ref>{{Cite web|url=http://www.mindrot.org/projects/jBCrypt/|title=jBCrypt - strong password hashing for Java|website=www.mindrot.org|language=en|access-date=2017-03-11}}</ref> <ref>{{Cite web|url=https://github.com/patrickfav/bcrypt|title=bcrypt - A Java standalone implementation of the bcrypt password hash function|website=github.com|language=en|access-date=2018-07-19}}</ref> Elixir, <ref>{{Cite web|url=https://github.com/riverrun/bcrypt_elixir|title=Bcrypt Elixir: Bcrypt password hashing algorithm for Elixir.|last=Whitlock|first=David|website=GitHub|publisher=riverrun}}</ref> Perl, <ref>{{Cite web|url=https://github.com/pyca/bcrypt/|title=bcrypt: Modern password hashing for your software and your servers|last=Stufft|first=Donald|publisher=}}</ref> Ruby dan bahasa lain
== Referensi ==
{{reflist}}
{{Hash kriptografi}}
[[Kategori:Perangkat lunak kriptografi]]
[[Kategori:Kriptografi]]
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