How is entropy and bits determined?

Discussion in 'Networking & Security' started by Gomar, May 9, 2011.

  1. Gomar

    Gomar Limp Gawd

    Messages:
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    Joined:
    Oct 25, 2007
    How is entropy and bits determined?

    if my password has 10 characters, then:
    95 ^ 10 - 59,873,693,923,837,894,000 [with symbols]
    62 ^ 10 - 839,299,365,868,340,200 [lower&upper case+numbers]
    26 ^ 10 - 141,167,095,653,376 [lower/upper case only]
    10 ^ 10 - 10,000,000,000 [numbers]

    Thus, even a 5 character pw is secure as the size of the pool of characters is very large.

    How does 2^128(bits) relate to this? 2 of what? 2 bits, 1 or 0?

    AMT pin has 4 digits. That is only 10^4 = 10000

    <t3 Q%f#8S
    Entropy: 48.3 bits
    close to
    G5riCf8A3s
    Entropy: 45.7 bits

    DRSVNBJXLR
    Entropy: 41 bits

    better and less to type than

    41264795296359061794
    Length: 20
    Entropy: 36.8 bits

    but finally:
    y~g1 bTehQ xPr4j1>)p9Z%u}
    Length: 25
    Strength: Very Strong
    Entropy: 130.4 bits
    Charset Size: 93 characters


    http://lastbit.com/pswcalc.asp
    pw length: 8
    Speed: 10m/sec
    # comps: 10
    Full ASCII
    up to 28 months [2.3years].

    Cool. Thus proving an 8 character pw is more than secure against anyone not hooking up 1000 PCs.