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diff --git a/README.md b/README.md new file mode 100644 index 0000000..74ca362 --- /dev/null +++ b/README.md @@ -0,0 +1,138 @@ +# INadvisable EXperimental Asymmetric Crypto Tool # + +Inexact is an experimental cryptographic tools, multi-platform, scriptable +complying with the KISS principle (Keep it simple and stupid). + +The main features are as follow: + +- Asymmetric encryption. +- Symmetric encryption. +- Variable length of encrypted messages for the same input message. +- Authenticated encrypted messages. +- Shell redirection compliant (using pipe). +- Base64 or modified base64 encoding output compatible with a URL path, DNS entry, or file name. + + +** WARNING : Inexact uses recent algorithms not approved nor by NIST or NSA ! ** + +## Encryption principles + +Inexact implements the following algorithms: + +- Norx 256bits +- Diffie-Hellman X25219 +- SHA3-256 +- DRNG chacha20 +- Argon2 + +An encrypted message is split into two parts: + +- The first one containing the parameters of the second part. +- The encrypted message. + +Rest of protocol: + +- The asymmetric encryption is achieved by using Diffie-Hellman with a 25519 + elliptical curve shared secret. +- A random buffer (rand1) with random size is generated from the chacha20 + algorithm. +- The shared secret from the Diffie-Hellman is hashed with rand1 buffer using + SHA3-256 and then used as a key for the Norx algorithm. +- The nonce for the Norx function of the second part is a SHA3-256 hash of + parameters of the first part and rand1 buffer. +- Argon2 is used as a challenge for the password of the private key. +- The symmetric encryption is based on ian asymmetric encryption by adding argon2 + challenge nonce and public key in the encrypted message. + +Schematic: + +``` +|---------------------------------------------------------------------------------------------------------------------------------- +| <encrypted 0 with len(tag) = 4> | tag0[4] | <rand> | <encrypted 1 with len(tag) = Y> | tag1[Y] | +| header[8]: len(part 0 + part 1) | | len(rand) = X | header: params | | +| key: sha3-256(nonce0+shared_secret) | | X >= 8 | key1: sha3-256(nonce1+shared_secret) | | +| nonce0: sha3-256 (rand+encrypted1) | | | nonce1: sha3-256(params+rand) | | +| message[5]=params:len(nonce1)=X len(tag1)=Y | | | message: data | | +|------------------ part 0 [9] --------------------------- |------------------------ part 1 -------------------------------------- | + +``` + + +## How to build + +For GNU/Linux and Mac OS X: + +``` + cd inexact + make +``` + +For Microsoft Windows using cross compilation on GNU/Linux: + +``` + cd inexact + make windows +``` + +## Usage + +Asymmetric encryption: + +``` + ./inexact --no-password -g -k alices.key -p alicep.key + ./inexact --no-password -g -k bobs.key -p bobp.key + echo "coucou alice" | ./inexact -e -k bobs.key -p alicep.key + rl9adQvAj20I3TIVDJrT3iSSrauqXKlF13nW91QfV80MopMNTCFLURfBHyLPurFnoFByRxv7kUvMkswzn8FoN4ibAkFizkmcpiMMnxWUQpIB3EhFsAg + echo "rl9adQvAj20I3TIVDJrT3iSSrauqXKlF13nW91QfV80MopMNTCFLURfBHyLPurFnoFByRxv7kUvMkswzn8FoN4ibAkFizkmcpiMMnxWUQpIB3EhFsAg" | ./inexact -d -k alices.key -p +bobp.key + coucou alice +``` + +Symmetric encryption: + +``` + echo "my secret" | ./inexact -e -s + Password : + Verifying, please re-enter : + C3B6_AMg7qPbYHDFE35hJzDFYIK40k48FiqCu1gQqSsNsU_7j8qZhh9vlzKvm_507fns1bih1tLZesKQfjLXFiauyskNBT6SmJazunQiesadWnoi1v2kye68lgfc96dOjk7F6pc2okGnNzzpv0SnRPNSGEq44 +fZ53IS6AIT89pmVAj631vBr95S2mQ7_Rj_99CaQ + echo +"C3B6_AMg7qPbYHDFE35hJzDFYIK40k48FiqCu1gQqSsNsU_7j8qZhh9vlzKvm_507fns1bih1tLZesKQfjLXFiauyskNBT6SmJazunQiesadWnoi1v2kye68lgfc96dOjk7F6pc2okGnNzzpv0SnRPNSGEq44f +Z53IS6AIT89pmVAj631vBr95S2mQ7_Rj_99CaQ" | ./inexact -d -s + Password : + my secret +``` + +Base64 output: + +``` + cat Makefile | ./inexact -e -k bobs.key -p alicep.key --base64 | base64 -d | xz -z > crypted_compressed + cat crypted_compressed | xz -d | base64 | ./inexact -d -k alices.key -p bobp.key +``` + +Variable encrypted message size (smallest): + +``` + echo "coucou Bob" | ./inexact -e -k alices.key -p bobp.key -w +``` + +Variable encrypted message size (400 chars): + +``` + echo "coucou Bob" | ./inexact -e -k alices.key -p bobp.key -c 400 +``` + +## Credits + +Inexact uses this libraries: + +- https://github.com/smuellerDD/chacha20_drng +- https://github.com/floodyberry/curve25519-donna +- http://web.mit.edu/freebsd/head/contrib/wpa/src/utils/base64.c +- https://github.com/brainhub/SHA3IUF +- https://github.com/norx +- https://github.com/WOnder93/argon2 +- https://nachtimwald.com/2017/09/24/hex-encode-and-decode-in-c/ +- https://github.com/argtable/argtable3 +- https://github.com/dsprenkels/randombytes + |