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Diffstat (limited to 'libraries/Sha/readme.txt')

-rw-r--r-- | libraries/Sha/readme.txt | 39 |

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diff --git a/libraries/Sha/readme.txt b/libraries/Sha/readme.txt new file mode 100644 index 0000000..bf1dbd8 --- /dev/null +++ b/libraries/Sha/readme.txt @@ -0,0 +1,39 @@ +Cryptosuite - A cryptographic library for Arduino +Copyright (C) 2010 Peter Knight (Cathedrow) + +This program is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +This program is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with this program. If not, see <http://www.gnu.org/licenses/>. + + +SHA implements secure hash functions that can be used for cryptography, data integrity and security purposes. + +Sha covers the following standards: + SHA-1 (FIPS 180-2) + SHA-256 (FIPS 180-2) + HMAC-SHA-1 (FIPS 198a) + HMAC-SHA-256 (FIPS 198a) + +What is a hash function? + A hash function takes a message, and generates a number. + A good hash function has the following properties: + The number is large enough that you will never find two messages with the same number (a 'collision') + It is computationally unfeasible to extract message information from its hash (without trying every possible combination) + A small (1 bit) change in the message will produce a huge (approximately half of all bits) change in the hash. + Fast to calculate + + SHA is slower than simple hashes (eg. parity), but has very high security - high enough to be used in currency transactions and confidential documents. + SHA-1 is currently secure, but there is some suggestion it may not be for much longer. + SHA-256 is slightly slower, but has higher security. + +What is an HMAC? + HMACs are Hashed Message Authentication Codes. Using them, it is possible to prove that you have a secret key without actually disclosing it. |