dkforest

commit 7facfbd8054c54969d29aa8ea0cf9d93bfdaefae
parent e892dadfb1760893ed2ae8d007b68f33d9d57d8e
Author: n0tr1v <n0tr1v@protonmail.com>
Date:   Sun, 29 Jan 2023 17:48:27 -0800

python version of torsign

Diffstat:
A
cmd/torsign/torsign.py
 | 
125
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 125 insertions(+), 0 deletions(-)
diff --git a/cmd/torsign/torsign.py b/cmd/torsign/torsign.py
@@ -0,0 +1,124 @@
+import argparse
+import base64
+import hashlib
+import sys
+
+
+def load_tor_key_from_disk(key_bytes):
+    if key_bytes[:29] != b'== ed25519v1-secret: type0 ==':
+        raise "Tor key does not start with Tor header"
+    expanded_sk = key_bytes[32:]
+    if len(expanded_sk) != 64:
+        raise "Tor private key has the wrong length"
+    return expanded_sk
+
+
+def sign(priv_key, msg):
+    return signatureWithESK(msg, priv_key, publickeyFromESK(priv_key))
+
+
+def publickeyFromESK(h):
+    a = decodeint(h[:32])
+    A = scalarmult(B,a)
+    return encodepoint(A)
+
+
+def decodeint(s):
+    return sum(2**i * bit(s,i) for i in range(0,b))
+
+
+def scalarmult(P,e):
+    if e == 0: return [0,1]
+    Q = scalarmult(P,e//2)
+    Q = edwards(Q,Q)
+    if e & 1: Q = edwards(Q,P)
+    return Q
+
+
+def inv(x):
+    return expmod(x,q-2,q)
+
+
+def expmod(b,e,m):
+    if e == 0: return 1
+    t = expmod(b,e//2,m)**2 % m
+    if e & 1: t = (t*b) % m
+    return t
+
+
+q = 2**255 - 19
+d = -121665 * inv(121666)
+I = expmod(2,(q-1)//4,q)
+
+
+def xrecover(y):
+    xx = (y*y-1) * inv(d*y*y+1)
+    x = expmod(xx,(q+3)//8,q)
+    if (x*x - xx) % q != 0: x = (x*I) % q
+    if x % 2 != 0: x = q-x
+    return x
+
+
+b = 256
+l = 2**252 + 27742317777372353535851937790883648493
+By = 4 * inv(5)
+Bx = xrecover(By)
+B = [Bx % q,By % q]
+
+
+def encodepoint(P):
+    x = P[0]
+    y = P[1]
+    bits = [(y >> i) & 1 for i in range(b - 1)] + [x & 1]
+    return b''.join([bytes([sum([bits[i * 8 + j] << j for j in range(8)])]) for i in range(b//8)])
+
+
+
+def edwards(P,Q):
+    x1 = P[0]
+    y1 = P[1]
+    x2 = Q[0]
+    y2 = Q[1]
+    x3 = (x1*y2+x2*y1) * inv(1+d*x1*x2*y1*y2)
+    y3 = (y1*y2+x1*x2) * inv(1-d*x1*x2*y1*y2)
+    return [x3 % q,y3 % q]
+
+
+def H(m):
+    return hashlib.sha512(m).digest()
+
+
+def bit(h,i):
+    return (h[i//8] >> (i%8)) & 1
+
+
+def Hint(m):
+    h = H(m)
+    return sum(2**i * bit(h,i) for i in range(2*b))
+
+
+def encodeint(y):
+    bits = [(y >> i) & 1 for i in range(b)]
+    return b''.join([bytes([sum([bits[i * 8 + j] << j for j in range(8)])]) for i in range(b//8)])
+
+
+def signatureWithESK(m,h,pk):
+    a = decodeint(h[:32])
+    tohint = b''.join([bytes([h[i]]) for i in range(b//8,b//4)]) + m
+    r = Hint(tohint)
+    R = scalarmult(B,r)
+    S = (r + Hint(encodepoint(R) + pk + m) * a) % l
+    return encodepoint(R) + encodeint(S)
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument('cert')
+parser.add_argument('-s', '--secret', default="hs_ed25519_secret_key")
+args = parser.parse_args()
+
+certFileName = sys.argv[1]
+msg = open(args.cert, 'rb').read()
+pem_key_bytes = open(args.secret, 'rb').read()
+privkey = load_tor_key_from_disk(pem_key_bytes)
+msg_sig = sign(privkey, msg)
+print(base64.b64encode(msg_sig).decode())
+\ No newline at end of file