Cryptography Stack Exchange by Kiwix

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

Most popular questions

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

165 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

53 Hashing or encrypting twice to increase security? 2011-09-25T06:56:17.897

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

53 Do these new insights into prime numbers affect encryption security? 2016-03-14T21:54:34.897

50 Is the software that uses PGP broken, or is it PGP itself? 2018-05-14T17:39:39.520

49 "SHA-256" vs "any 256 bits of SHA-512", which is more secure? 2012-07-06T05:03:41.510

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

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

48 One Encryption, Many Decryption Keys 2016-08-16T19:23:23.580

48 Timing attack and good coding practices 2016-11-21T06:52:41.787

48 How do hashes really ensure uniqueness? 2018-10-22T11:35:28.603

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