(This is a snapshot of my old weblog. New posts and selected republished essays can be found at raganwald.com.)
Saturday, June 14, 2008
Today's public key is { :n => 46, :e => 5 }
And the secret message is: [11, 38, 13, 0, 24, 36, 16, 26, 36, 18, 24, 36, 1, 16, 21, 11, 17, 13, 0, 24]
def rsa_encrypt(message, public_key)
n = public_key[:n]
e = public_key[:e]
n_arr = message.downcase.scan(/[a-z]| /).map { |character|
"abcdefghijklmnopqrstuvwxyz ".index(character)
}
n_arr.map { |m|
(m ** e).modulo n
}
end
def rsa_decrypt(ciphertext, private_key)
n = private_key[:n]
d = private_key[:d]
n_arr = ciphertext.map { |c|
(c ** d).modulo n
}
n_arr.map { |n| "abcdefghijklmnopqrstuvwxyz "[n,1] }.join('')
endAnd the secret message is: [11, 38, 13, 0, 24, 36, 16, 26, 36, 18, 24, 36, 1, 16, 21, 11, 17, 13, 0, 24]
Comments on “Today's public key is { :n => 46, :e => 5 }”:
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I was going try to and write a brute force breaker, but then I thought if :e is 5, :d is probably pretty low too.
Happy Birthday!
Happy Birthday!
What a coincidence! I was trying to remember how to compute d before going out to my b-day lunch :-)
phi = (p - 1) * (q - 1)
d * e = 1 + k * phi
Happy birthday!
phi = (p - 1) * (q - 1)
d * e = 1 + k * phi
Happy birthday!
That's actually a substitution cipher generated in an obfuscated fashion. But happy birthday!
(and, unfortunately, the decription program was written in python, "for i in xrange(26): print chr(ord('a') + i), (i ** 5) % 46")
(and, unfortunately, the decription program was written in python, "for i in xrange(26): print chr(ord('a') + i), (i ** 5) % 46")
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