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Diffstat (limited to 'testing/web-platform/tests/fledge/tentative/resources/ed25519.py')
-rw-r--r-- | testing/web-platform/tests/fledge/tentative/resources/ed25519.py | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/testing/web-platform/tests/fledge/tentative/resources/ed25519.py b/testing/web-platform/tests/fledge/tentative/resources/ed25519.py new file mode 100644 index 0000000000..53e548ab8e --- /dev/null +++ b/testing/web-platform/tests/fledge/tentative/resources/ed25519.py @@ -0,0 +1,289 @@ +# ed25519.py - Optimized version of the reference implementation of Ed25519 +# +# Written in 2011? by Daniel J. Bernstein <djb@cr.yp.to> +# 2013 by Donald Stufft <donald@stufft.io> +# 2013 by Alex Gaynor <alex.gaynor@gmail.com> +# 2013 by Greg Price <price@mit.edu> +# +# To the extent possible under law, the author(s) have dedicated all copyright +# and related and neighboring rights to this software to the public domain +# worldwide. This software is distributed without any warranty. +# +# You should have received a copy of the CC0 Public Domain Dedication along +# with this software. If not, see +# <http://creativecommons.org/publicdomain/zero/1.0/>. +# +# Downloaded from https://raw.githubusercontent.com/pyca/ed25519/main/ed25519.py +# on April 1, 2024. + +""" +NB: This code is not safe for use with secret keys or secret data. +The only safe use of this code is for verifying signatures on public messages. + +Functions for computing the public key of a secret key and for signing +a message are included, namely publickey_unsafe and signature_unsafe, +for testing purposes only. + +The root of the problem is that Python's long-integer arithmetic is +not designed for use in cryptography. Specifically, it may take more +or less time to execute an operation depending on the values of the +inputs, and its memory access patterns may also depend on the inputs. +This opens it to timing and cache side-channel attacks which can +disclose data to an attacker. We rely on Python's long-integer +arithmetic, so we cannot handle secrets without risking their disclosure. +""" + +import hashlib + + +__version__ = "1.0.dev0" + + +b = 256 +q = 2**255 - 19 +l = 2**252 + 27742317777372353535851937790883648493 + + +def H(m): + return hashlib.sha512(m).digest() + + +def pow2(x, p): + """== pow(x, 2**p, q)""" + while p > 0: + x = x * x % q + p -= 1 + return x + + +def inv(z): + r"""$= z^{-1} \mod q$, for z != 0""" + # Adapted from curve25519_athlon.c in djb's Curve25519. + z2 = z * z % q # 2 + z9 = pow2(z2, 2) * z % q # 9 + z11 = z9 * z2 % q # 11 + z2_5_0 = (z11 * z11) % q * z9 % q # 31 == 2^5 - 2^0 + z2_10_0 = pow2(z2_5_0, 5) * z2_5_0 % q # 2^10 - 2^0 + z2_20_0 = pow2(z2_10_0, 10) * z2_10_0 % q # ... + z2_40_0 = pow2(z2_20_0, 20) * z2_20_0 % q + z2_50_0 = pow2(z2_40_0, 10) * z2_10_0 % q + z2_100_0 = pow2(z2_50_0, 50) * z2_50_0 % q + z2_200_0 = pow2(z2_100_0, 100) * z2_100_0 % q + z2_250_0 = pow2(z2_200_0, 50) * z2_50_0 % q # 2^250 - 2^0 + return pow2(z2_250_0, 5) * z11 % q # 2^255 - 2^5 + 11 = q - 2 + + +d = -121665 * inv(121666) % q +I = pow(2, (q - 1) // 4, q) + + +def xrecover(y): + xx = (y * y - 1) * inv(d * y * y + 1) + x = pow(xx, (q + 3) // 8, q) + + if (x * x - xx) % q != 0: + x = (x * I) % q + + if x % 2 != 0: + x = q - x + + return x + + +By = 4 * inv(5) +Bx = xrecover(By) +B = (Bx % q, By % q, 1, (Bx * By) % q) +ident = (0, 1, 1, 0) + + +def edwards_add(P, Q): + # This is formula sequence 'addition-add-2008-hwcd-3' from + # http://www.hyperelliptic.org/EFD/g1p/auto-twisted-extended-1.html + (x1, y1, z1, t1) = P + (x2, y2, z2, t2) = Q + + a = (y1 - x1) * (y2 - x2) % q + b = (y1 + x1) * (y2 + x2) % q + c = t1 * 2 * d * t2 % q + dd = z1 * 2 * z2 % q + e = b - a + f = dd - c + g = dd + c + h = b + a + x3 = e * f + y3 = g * h + t3 = e * h + z3 = f * g + + return (x3 % q, y3 % q, z3 % q, t3 % q) + + +def edwards_double(P): + # This is formula sequence 'dbl-2008-hwcd' from + # http://www.hyperelliptic.org/EFD/g1p/auto-twisted-extended-1.html + (x1, y1, z1, t1) = P + + a = x1 * x1 % q + b = y1 * y1 % q + c = 2 * z1 * z1 % q + # dd = -a + e = ((x1 + y1) * (x1 + y1) - a - b) % q + g = -a + b # dd + b + f = g - c + h = -a - b # dd - b + x3 = e * f + y3 = g * h + t3 = e * h + z3 = f * g + + return (x3 % q, y3 % q, z3 % q, t3 % q) + + +def scalarmult(P, e): + if e == 0: + return ident + Q = scalarmult(P, e // 2) + Q = edwards_double(Q) + if e & 1: + Q = edwards_add(Q, P) + return Q + + +# Bpow[i] == scalarmult(B, 2**i) +Bpow = [] + + +def make_Bpow(): + P = B + for i in range(253): + Bpow.append(P) + P = edwards_double(P) + + +make_Bpow() + + +def scalarmult_B(e): + """ + Implements scalarmult(B, e) more efficiently. + """ + # scalarmult(B, l) is the identity + e = e % l + P = ident + for i in range(253): + if e & 1: + P = edwards_add(P, Bpow[i]) + e = e // 2 + assert e == 0, e + return P + + +def encodeint(y): + bits = [(y >> i) & 1 for i in range(b)] + return bytes( + [sum([bits[i * 8 + j] << j for j in range(8)]) for i in range(b // 8)] + ) + + +def encodepoint(P): + (x, y, z, t) = P + zi = inv(z) + x = (x * zi) % q + y = (y * zi) % q + bits = [(y >> i) & 1 for i in range(b - 1)] + [x & 1] + return bytes( + [sum([bits[i * 8 + j] << j for j in range(8)]) for i in range(b // 8)] + ) + + +def bit(h, i): + return (h[i // 8] >> (i % 8)) & 1 + + +def publickey_unsafe(sk): + """ + Not safe to use with secret keys or secret data. + + See module docstring. This function should be used for testing only. + """ + h = H(sk) + a = 2 ** (b - 2) + sum(2**i * bit(h, i) for i in range(3, b - 2)) + A = scalarmult_B(a) + return encodepoint(A) + + +def Hint(m): + h = H(m) + return sum(2**i * bit(h, i) for i in range(2 * b)) + + +def signature_unsafe(m, sk, pk): + """ + Not safe to use with secret keys or secret data. + + See module docstring. This function should be used for testing only. + """ + h = H(sk) + a = 2 ** (b - 2) + sum(2**i * bit(h, i) for i in range(3, b - 2)) + r = Hint(bytes([h[j] for j in range(b // 8, b // 4)]) + m) + R = scalarmult_B(r) + S = (r + Hint(encodepoint(R) + pk + m) * a) % l + return encodepoint(R) + encodeint(S) + + +def isoncurve(P): + (x, y, z, t) = P + return ( + z % q != 0 + and x * y % q == z * t % q + and (y * y - x * x - z * z - d * t * t) % q == 0 + ) + + +def decodeint(s): + return sum(2**i * bit(s, i) for i in range(0, b)) + + +def decodepoint(s): + y = sum(2**i * bit(s, i) for i in range(0, b - 1)) + x = xrecover(y) + if x & 1 != bit(s, b - 1): + x = q - x + P = (x, y, 1, (x * y) % q) + if not isoncurve(P): + raise ValueError("decoding point that is not on curve") + return P + + +class SignatureMismatch(Exception): + pass + + +def checkvalid(s, m, pk): + """ + Not safe to use when any argument is secret. + + See module docstring. This function should be used only for + verifying public signatures of public messages. + """ + if len(s) != b // 4: + raise ValueError("signature length is wrong") + + if len(pk) != b // 8: + raise ValueError("public-key length is wrong") + + R = decodepoint(s[: b // 8]) + A = decodepoint(pk) + S = decodeint(s[b // 8 : b // 4]) + h = Hint(encodepoint(R) + pk + m) + + (x1, y1, z1, t1) = P = scalarmult_B(S) + (x2, y2, z2, t2) = Q = edwards_add(R, scalarmult(A, h)) + + if ( + not isoncurve(P) + or not isoncurve(Q) + or (x1 * z2 - x2 * z1) % q != 0 + or (y1 * z2 - y2 * z1) % q != 0 + ): + raise SignatureMismatch("signature does not pass verification") |