I have a 128-bit Bignum that I need to pack into a binary string in
order to pass it to MD5.digest(). But there doesn’t appear to be a
format for Array#pack that would accommodate such a large number; the
biggest appears to be “L”, which is only a quarter the size I need.
What’s the best way to do this?
Dan
–
airboss@nodewarrior.org
www.nodewarrior.org
ignorami: n:
The art of folding problem users into representational shapes.
Hi,
I have a 128-bit Bignum that I need to pack into a binary string in
order to pass it to MD5.digest(). But there doesn’t appear to be a
format for Array#pack that would accommodate such a large number; the
biggest appears to be “L”, which is only a quarter the size I need.What’s the best way to do this?
Perhaps not as efficient as you expect:
a)
b = 128-bit bignum value
data =
4.times{|i|
data.unshift (b>>i*32)&0xffffffff
}
data.pack(“NNNN”)
b)
[sprintf(“%0128b”, b)].pack(“B*”)
matz.
In message “pack()ing Bignums” on 02/06/12, Dan Debertin airboss@nodewarrior.org writes:
Yukihiro Matsumoto writes:
Perhaps not as efficient as you expect:
a)
b = 128-bit bignum value
data =
4.times{|i|
data.unshift (b>>i*32)&0xffffffff
}
data.pack(“NNNN”)
This works:
data.unshift((b>>i*32)&0xffffffff)
Without the enclosing parens it tries to & the array, it appears.
b)
[sprintf(“%0128b”, b)].pack(“B*”)
Also works. Many thanks.
Dan
–
airboss@nodewarrior.org
www.nodewarrior.org
ignorami: n:
The art of folding problem users into representational shapes.
data.unshift (b>>i*32)&0xffffffff
[...]
data.unshift((b>>i*32)&0xffffffff)
Without the enclosing parens it tries to & the array, it appears.
This is a difference 1.6, 1.7
Guy Decoux
Hi,
In message “Re: pack()ing Bignums” on 02/06/12, ts decoux@moulon.inra.fr writes:
data.unshift (b>>i32)&0xffffffff
[…]
data.unshift((b>>i32)&0xffffffff)Without the enclosing parens it tries to & the array, it appears.
This is a difference 1.6, 1.7
Oops, 1.7 is too smart. I should have checked on 1.6 as well.
matz.