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27 lines
798 B
Ruby
27 lines
798 B
Ruby
require 'digest'
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module ActiveSupport
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module SecurityUtils
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# Constant time string comparison.
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#
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# The values compared should be of fixed length, such as strings
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# that have already been processed by HMAC. This should not be used
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# on variable length plaintext strings because it could leak length info
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# via timing attacks.
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def secure_compare(a, b)
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return false unless a.bytesize == b.bytesize
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l = a.unpack "C#{a.bytesize}"
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res = 0
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b.each_byte { |byte| res |= byte ^ l.shift }
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res == 0
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end
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module_function :secure_compare
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def variable_size_secure_compare(a, b) # :nodoc:
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secure_compare(::Digest::SHA256.hexdigest(a), ::Digest::SHA256.hexdigest(b))
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end
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module_function :variable_size_secure_compare
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end
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end
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