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| ===Strength of Authentication Mechanism===
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| In FIPS mode, the NSS cryptographic module imposes the following requirements on the password.
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| * The password must be at least '''seven''' characters long.
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| * The password must consist of characters from '''three or more character classes'''. We define five character classes: digits (0-9), ASCII lowercase letters, ASCII uppercase letters, ASCII non-alphanumeric characters (such as space and punctuation marks), and non-ASCII characters. If an ASCII uppercase letter is the first character of the password, the uppercase letter is not counted toward its character class. Similarly, if a digit is the last character of the password, the digit is not counted toward its character class.
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| To estimate the probability that a random guess of the password will succeed, we assume that
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| * the characters of the password are '''independent''' with each other, and
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| * the probability of guessing an individual character of the password is < '''1/10'''.
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| Since the password is >= 7 characters long, the probability that a random guess of the password will succeed is < (1/10)^7 = 1/10,000,000.
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| After each failed authentication attempt in FIPS mode, the NSS cryptographic module inserts a one-second delay before returning to the caller, allowing at most 60 authentication attempts during a one-minute period. Therefore, the probability of a successful random guess of the password during a one-minute period is < 60 * 1/10,000,000 = 0.6 * (1/100,000).
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