DERGen.py

# OpenSSL "asn1parse -genconf" compatible DER configuration (RFC3447) generator
# Using a bunch of public domain functions because they just work(TM)
# -- SmilingWolf

# Extended Euclidean Algorithm
def xgcd(b, a):
    x0, x1, y0, y1 = 1, 0, 0, 1
    while a != 0:
        q, b, a = b // a, a, b % a
        x0, x1 = x1, x0 - q * x1
        y0, y1 = y1, y0 - q * y1
    return  b, x0, y0

# Least common multiple
def lcm(a, b):
    return a * b / xgcd(a, b)[0]

# Modular inverse
def modinv(a, m):
    g, x, y = xgcd(a, m)
    if g != 1:
        raise Exception('modular inverse does not exist')
    else:
        return x % m

E = 65537
P = 398075086424064937397125500550386491199064362342526708406385189575946388957261768583317
Q = 472772146107435302536223071973048224632914695302097116459852171130520711256363590397527

N = P * Q
PQlambda = lcm(P - 1, Q - 1)
D = modinv(E, PQlambda)
exp1 = D % (P - 1)
exp2 = D % (Q - 1)
coeff = modinv(Q, P)

print('asn1=SEQUENCE:private_key')
print('[private_key]')
print('version=INTEGER:0')
print('n=INTEGER:%d' % N)
print('e=INTEGER:%d' % E)
print('d=INTEGER:%d' % D)
print('p=INTEGER:%d' % P)
print('q=INTEGER:%d' % Q)
print('exp1=INTEGER:%d' % exp1)
print('exp2=INTEGER:%d' % exp2)
print('coeff=INTEGER:%d' % coeff)