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Diffstat (limited to 'lib/srp/util.rb')
-rw-r--r-- | lib/srp/util.rb | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/lib/srp/util.rb b/lib/srp/util.rb new file mode 100644 index 0000000..6792105 --- /dev/null +++ b/lib/srp/util.rb @@ -0,0 +1,53 @@ +require 'digest' +require 'openssl' + +module SRP + module Util + + # constants both sides know + PRIME_N = <<-EOS.split.join.hex # 1024 bits modulus (N) +eeaf0ab9adb38dd69c33f80afa8fc5e86072618775ff3c0b9ea2314c9c25657 +6d674df7496ea81d3383b4813d692c6e0e0d5d8e250b98be48e495c1d6089da +d15dc7d7b46154d6b6ce8ef4ad69b15d4982559b297bcf1885c529f566660e5 +7ec68edbc3c05726cc02fd4cbf4976eaa9afd5138fe8376435b9fc61d2fc0eb +06e3 + EOS + GENERATOR = 2 # g + + # a^n (mod m) + def modpow(a, n, m) + r = 1 + while true + r = r * a % m if n[0] == 1 + n >>= 1 + return r if n == 0 + a = a * a % m + end + end + + def sha1_hex(h) + Digest::SHA1.hexdigest([h].pack('H*')) + end + + def sha1_str(s) + Digest::SHA1.hexdigest(s) + end + + def bigrand(bytes) + OpenSSL::Random.random_bytes(bytes).unpack("H*")[0] + end + + def multiplier + n = PRIME_N + g = GENERATOR + nhex = '%x' % [n] + nlen = nhex.length + (nhex.length.odd? ? 1 : 0 ) + ghex = '%x' % [g] + hashin = '0' * (nlen - nhex.length) + nhex \ + + '0' * (nlen - ghex.length) + ghex + sha1_hex(hashin).hex % n + end + end + +end + |