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This commit is contained in:
Pascal Engélibert 2026-06-23 20:22:16 +02:00
commit abcb3137f1
6 changed files with 89 additions and 16 deletions
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85
content/blog/flash-filesystem-encryption/diagram.py
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@ -4,6 +4,8 @@ GNU AGPL v3, CopyLeft 2025 Pascal Engélibert [(why copyleft?)](https://txmn.tk/
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, version 3 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.
This program's output may be licensed as you wish, no obligation to credit and provide a link to the source code, even if it's always better ;)
"""
import math
@ -53,23 +55,24 @@ SVG = """\
"""
class Block:
def __init__(self, svg, x, y, r):
def __init__(self, svg, x, y, rx, ry=None):
self.svg = svg
self.x = x
self.y = y
self.r = r
self.rx = rx
self.ry = ry if ry != None else rx
def to(self, block):
if self.x == block.x:
if self.y > block.y:
self.svg.t += arrow(self.x, self.y-self.r, block.x, block.y+block.r)
self.svg.t += arrow(self.x, self.y-self.ry, block.x, block.y+block.ry)
else:
self.svg.t += arrow(self.x, self.y+self.r, block.x, block.y-block.r)
self.svg.t += arrow(self.x, self.y+self.ry, block.x, block.y-block.ry)
elif self.y == block.y:
if self.x > block.x:
self.svg.t += arrow(self.x-self.r, self.y, block.x+block.r, block.y)
self.svg.t += arrow(self.x-self.rx, self.y, block.x+block.rx, block.y)
else:
self.svg.t += arrow(self.x+self.r, self.y, block.x-block.r, block.y)
self.svg.t += arrow(self.x+self.rx, self.y, block.x-block.rx, block.y)
XOR_R = 8
ENCRYPT_SIZE = 32
@ -126,12 +129,12 @@ class Svg:
"""
return Block(self, x, y, XOR_R)
def encrypt(self, x, y):
def encrypt(self, x, y, text="E"):
xl = x-ENCRYPT_SIZE//2
yt = y-ENCRYPT_SIZE//2
self.t += f"""\
<rect x="{xl}" y="{yt}" width="{ENCRYPT_SIZE}" height="{ENCRYPT_SIZE}"/>
<text class="t" x="{x}" y="{y}">E</text>
<text class="t" x="{x}" y="{y}">{text}</text>
"""
return Block(self, x, y, ENCRYPT_SIZE//2)
@ -164,7 +167,13 @@ class Svg:
tx_ = (tx+0.5)*cell_w+xl
ty_ = (ty+0.5)*cell_h+yt
self.t += f"""<text class="t" x="{tx_}" y="{ty_}">{t}</text>\n"""
return Block(self, x, y, ENCRYPT_SIZE//2)
for (x1, y1, x2, y2) in borders:
x1_ = x1*cell_w+xl
y1_ = y1*cell_h+yt
x2_ = x2*cell_w+xl
y2_ = y2*cell_h+yt
self.t += f"""<line x1="{x1_}" y1="{y1_}" x2="{x2_}" y2="{y2_}"/>\n"""
return Block(self, x, y, w//2, h//2)
def knot(self, x, y):
self.t += f"""\
@ -380,13 +389,58 @@ def chacha_encryption():
(0.5, 3, "count"),
(2.5, 3, "nonce"),
],
[])
P = s.text(16, 144, "P")
E = s.encrypt(64, 96)
X = s.xor(64, 144)
C = s.text(64, 180, "C")
[
(0, 1, 4, 1),
(0, 3, 4, 3),
(2, 3, 2, 4),
])
P = s.text(16, 160, "P")
E = s.encrypt(64, 112)
X = s.xor(64, 160)
C = s.text(64, 200, "C")
B.to(E)
E.to(X)
P.to(X)
X.to(C)
return SVG.format(body=s.t, title="ChaCha Encryption", w=372, h=192, **ARGS)
return SVG.format(body=s.t, title="ChaCha Encryption", w=128, h=224, **ARGS)
def chacha_xts():
s = Svg()
B = s.block(64, 96, 4, 4, [
(1.5, 0, "const"),
(1.5, 1.5, "K"),
(0.5, 3, "count"),
(2.5, 3, "nonce"),
],
[
(0, 1, 4, 1),
(0, 3, 4, 3),
(2, 3, 2, 4),
])
P = s.text(304, 16, "P")
X1 = s.xor(304, 56)
E1 = s.encrypt(304, 96, 'E<tspan dy="6">r</tspan>')
X2 = s.xor(304, 144)
C = s.text(304, 180, "C")
E2 = s.encrypt(176, 96)
J = s.text(240, 16, "j")
A = s.square(240, 96, '×α <tspan dy="-8">j</tspan>')
B.to(E2)
P.to(X1)
X1.to(E1)
E1.to(X2)
X2.to(C)
E2.to(A)
J.to(A)
s.t += arrow_path([(256,96), (272,96), (272,56), (296,56)])
s.t += arrow_path([(256,96), (272,96), (272,144), (296,144)])
return SVG.format(body=s.t, title="XTS", w=372, h=192, **ARGS)
def save(name, data):
f = open(f"{name}.svg", "w")
@ -399,3 +453,4 @@ if __name__ == "__main__":
save("cbc", cbc())
save("xts", xts())
save("../flash-filesystem-encryption-2/chacha-encryption", chacha_encryption())
save("../flash-filesystem-encryption-2/chacha-xts", chacha_xts())