Awesome

RNCryptor-Erlang

Erlang implementation of Rob Napier's <a href="https://github.com/RNCryptor/RNCryptor">RNCryptor</a> V3 data format for both password-based and key-based AES128 & AES256 encryption / decryption.

See <a href="https://github.com/RNCryptor/RNCryptor-Spec/blob/master/RNCryptor-Spec-v3.md">RNCryptor V3</a> for more information.

Notes

Key Lengths

128-bit and 256-bit AES keys are supported.

Key-Based Usage: encrypt/2 & decrypt/2

Function encrypt/2 generates a random 32-bit Hmac Key and decrypt/2 parses the first 32-bits of the RNPacket as the Hmac Key (per the RNCryptor V3 spec).

> Key256 = crypto:strong_rand_bytes(32).

  <<102,95,113,93,223,178,0,103,196,34,189,16,41,238,16,55,
    170,218,37,146,219,181,161,182,228,116,185,182,17,130,161,134>>

> RNPacket256 = rncryptor:encrypt(Key256, <<"dingo sky">>).

  <<221,66,120,25,237,0,2,15,154,157,146,212,231,250,107,73,
    80,92,45,221,99,27,194,86,20,58,236,127,105,60,112,121,
    3,0,181,96,160,2,195,119,25,183,113,27,161,33,148,75,
    133,90,113,57,191,231,98,62,194,229,26,204,201,14,162,113,
    216,152,170,194,133,161,113,1,239,219,189,223,147,10,101,128,
    37,235,64,17,178,10,219,250,138,6,219,179,255,169,131,21,
    254,102>>

> rncryptor:decrypt(Key256, RNPacket256).

  <<"dingo sky">>

Utility functions are provided to create hex representations of binary values:

> rncryptor_util:bin_to_hex(Key256).

  "665F715DDFB20067C422BD1029EE1037AADA2592DBB5A1B6E474B9B61182A186"

> rncryptor_util:bin_to_hex(RNPacket).

  "DD427819ED00020F9A9D92D4E7FA6B49505C2DDD631BC256143AEC7F693C70790300B560A002C37719B7711BA121944B855A7139BFE7623EC2E51ACCC90EA271D898AAC285A17101EFDBBDDF930A658025EB4011B20ADBFA8A06DBB3FFA98315FE66"

Using 128-bit keys:

> Key128 = crypto:strong_rand_bytes(16).

  <<150,78,200,225,141,34,253,182,26,172,157,148,60,8,39,101>>

> RNPacket128 = rncryptor:encrypt(Key128, <<"dingo sky">>).

  <<90,202,44,216,211,92,21,96,125,180,254,163,252,54,200,124,
    251,91,11,46,20,9,43,20,243,66,227,1,29,183,49,65,
    3,0,68,137,36,117,29,113,123,63,219,60,15,20,116,32,
    228,68,90,66,110,208,61,43,140,123,134,252,102,114,92,128,
    210,216,151,156,90,79,233,161,36,40,205,117,207,10,156,77,
    234,90,25,130,162,111,252,159,250,198,188,11,106,252,37,203,
    4,42>>

> rncryptor:decrypt(Key128, RNPacket128).

  <<"dingo sky">>

Key-Based Usage: encrypt/3 & decrypt/3

Functions encrypt/3 and decrypt/3 take an explicit Hmac Key value.

> HmacKey = crypto:strong_rand_bytes(32).

  <<11,228,218,183,82,229,34,121,247,147,30,69,223,47,199,121,
  79,183,114,20,147,146,162,78,219,27,127,207,197,1,66,211>>

> RNCryptor = rncryptor:encrypt(Key256, HmacKey, <<"dingo sky">>).

  <<3,0,175,16,130,145,145,253,126,101,236,27,228,191,90,207,
    65,0,172,223,99,232,87,170,114,223,82,54,51,163,132,48,
    231,186,152,187,72,57,167,53,189,17,144,231,222,61,98,233,
    149,148,19,103,139,144,201,243,157,121,113,21,100,25,174,211,
    237,77>>

> rncryptor:decrypt(Key256, HmacKey, RNCryptor).

  <<"dingo sky">>

Or, using decrypt/2:

> RNPacket = <<HmacKey/binary, RNCryptor/binary>>.

  <<11,228,218,183,82,229,34,121,247,147,30,69,223,47,199,121,
    79,183,114,20,147,146,162,78,219,27,127,207,197,1,66,211,
    3,0,175,16,130,145,145,253,126,101,236,27,228,191,90,207,
    65,0,172,223,99,232,87,170,114,223,82,54,51,163,132,48,
    231,186,152,187,72,57,167,53,189,17,144,231,222,61,98,233,
    149,148,19,103,139,144,201,243,157,121,113,21,100,25,174,211,
    237,77>>

> rncryptor:decrypt(Key256, RNPacket).

  <<"dingo sky">>

Password-Based Usage:

> RNCryptor = rncryptor:encrypt_pw(<<"super secret">>, <<"dingo sky">>).

  <<3,1,172,64,176,130,224,97,45,148,247,56,20,40,94,182,
    125,63,163,114,177,167,183,106,76,109,126,250,243,15,37,175,
    64,104,253,133,20,17,129,27,95,164,245,54,57,237,250,215,
    254,33,91,57,211,80,16,217,167,165,7,31,175,64,158,67,
    148,222,193,47,142,241,198,208,189,217,75,255,28,140,71,5,
    134,253>>

> rncryptor:decrypt_pw(<<"super secret">>, RNCryptor).

  <<"dingo sky">>

Development Environment

Developed on Mac OS X 10.10 using Erlang 17.5.
Use <a href="https://github.com/rebar/rebar">rebar</a> to:
- rebar compile : Compile source
- rebar eunit : Run all 54 eunit tests
- rebar doc : Generate documentation

Licence