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Constant compare #282

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Merged
tenderlove merged 2 commits into from
Oct 29, 2024
Merged

Constant compare #282

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9597533
Use a constant-time secure comparison for passwords
Aug 6, 2015
a7a868e
Lets not allocate anything
tenderlove Oct 29, 2024
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9 changes: 8 additions & 1 deletion lib/bcrypt/password.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,14 @@ def initialize(raw_hash)
#
# secret == @password # => probably False, because the secret is not a BCrypt::Password instance.
def ==(secret)
super(BCrypt::Engine.hash_secret(secret, @salt))
hash = BCrypt::Engine.hash_secret(secret, @salt)

return false if hash.strip.empty? || strip.empty? || hash.bytesize != bytesize

# Constant time comparison so they can't tell the length.
res = 0
bytesize.times { |i| res |= getbyte(i) ^ hash.getbyte(i) }
res == 0
end
alias_method :is_password?, :==

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