Cryptography Stack Exchange by Kiwix

Q&A for software developers, mathematicians and others interested in cryptography

Most popular questions

360 Should we MAC-then-encrypt or encrypt-then-MAC? 2011-07-19T21:39:56.770

189 How much would it cost in U.S. dollars to brute force a 256 bit key in a year? 2011-11-08T10:51:55.030

170 What are the differences between a digital signature, a MAC and a hash? 2012-12-10T12:16:02.220

165 Time Capsule cryptography? 2011-06-22T17:47:53.637

153 Why is elliptic curve cryptography not widely used, compared to RSA? 2011-11-15T06:19:31.803

153 Why is writing your own encryption discouraged? 2017-01-25T18:19:44.737

148 Should we trust the NIST-recommended ECC parameters? 2013-09-09T03:07:52.923

135 Why can't we reverse hashes? 2017-04-06T16:25:11.253

119 What is the main difference between a key, an IV and a nonce? 2012-10-05T08:20:27.690

113 Should we sign-then-encrypt, or encrypt-then-sign? 2012-11-22T16:55:00.610

112 Can you help me understand what a cryptographic "salt" is? 2012-01-30T14:01:52.930

111 How big an RSA key is considered secure today? 2012-03-03T02:51:20.540

102 How should I calculate the entropy of a password? 2011-08-11T06:03:30.270

95 What is the new attack on SHA-1 "SHAttered" and how does it work? 2017-02-23T13:40:35.063

94 Are there two known strings which have the same MD5 hash value? 2011-12-11T08:57:56.650

93 If WhatsApp cannot read our message, how can the media forwarding happen in an instant? 2018-04-18T06:13:27.647

92 Taking advantage of one-time pad key reuse? 2011-07-13T03:24:02.727

90 How is CipherCloud doing homomorphic encryption? 2012-08-25T15:09:14.477

87 Has SHA256 been broken by Treadwell Stanton DuPont? 2019-09-11T14:55:47.953

84 Guarding against cryptanalytic breakthroughs: combining multiple hash functions 2011-07-29T15:52:46.960

84 Is modern encryption needlessly complicated? 2011-09-02T03:16:42.643

83 Is AES-256 weaker than 192 and 128 bit versions? 2012-10-19T22:02:16.503

82 How can I generate large prime numbers for RSA? 2011-07-13T10:10:49.897

81 What is the difference between PKCS#5 padding and PKCS#7 padding 2013-07-04T21:18:51.007

80 In end-to-end encryption, doesn't the server need to be trusted? 2017-12-19T14:30:35.733

79 Why doesn't SSH use TLS? 2018-06-24T12:28:51.913

77 How secure is AES-256? 2012-04-01T16:15:54.610

75 What are the practical differences between 256-bit, 192-bit, and 128-bit AES encryption? 2011-07-12T19:44:46.490

75 Should I use ECB or CBC encryption mode for my block cipher? 2011-07-21T13:19:43.667

74 Layman's explanation of encryption backdoors 2016-02-17T12:11:17.360

73 What is the "Random Oracle Model" and why is it controversial? 2011-09-30T15:38:37.803

73 What is the difference between CBC and GCM mode? 2012-04-08T23:20:36.817

73 How come Public key cryptography wasn't discovered earlier? 2018-05-25T09:03:12.587

73 Who verifies the trust of certificate authorities? 2019-12-05T07:38:45.673

72 How do I explain zero knowledge proof to my 7 year old cousin? 2018-03-21T07:23:29.283

71 How does RSA signature verification work? 2013-08-21T11:47:16.693

68 How does one attack a two-time pad (i.e. one time pad with key reuse)? 2012-03-31T22:29:02.540

67 How are primes generated for RSA? 2012-03-01T12:54:31.007

65 How can I use asymmetric encryption, such as RSA, to encrypt an arbitrary length of plaintext? 2011-07-12T19:27:47.580

64 Why does the FBI ask Apple for help to decrypt an iPhone? 2016-02-18T11:38:29.543

61 Technical feasibility of decrypting https by replacing the computer's PRNG 2013-07-14T02:39:37.367

61 Why does my SSH private key still work after changing some bytes in the file? 2016-01-09T19:15:55.613

60 Can you explain Bleichenbacher's CCA attack on PKCS#1 v1.5? 2014-01-02T14:24:59.990

59 What are the advantages of TOTP over HOTP? 2012-03-29T23:34:53.963

59 Impacts of not using RSA exponent of 65537 2012-07-01T04:25:02.167

59 What is safer: ZipCrypto or AES-256? 2012-09-13T13:55:27.977

59 SHA512 faster than SHA256? 2015-06-16T20:16:32.677

59 Signal vs Telegram in terms of protocols? 2015-12-20T21:53:23.500

59 Soft question: Examples where lack of mathematical rigour cause security breaches? 2019-06-03T13:35:22.390

55 What makes a hash function good for password hashing? 2011-07-12T19:59:44.993

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