alice and bob authenticated encryption avalanche effect birthday problem block cipher bruce schneier brute force attack cbc-mac ccm mode cryptrec cwc mode cryptanalysis cryptographic hash function cryptographically secure pseudorandom number generator cryptography data authentication algorithm digital signature discrete logarithm eax mode faq haval hmac hash collision history of cryptography lm hash meet-in-the-middle attack message authentication code mihir bellare n-hash nessie nist hash function competition ocb mode postscript preimage attack probability theory public-key cryptography ripemd rsa security rainbow table sha hash functions snefru steganography stream cipher symmetric-key algorithm topics in cryptography umac upper and lower bounds