Digest and MAC codes

Anvil crypto library can create message hash codes or checksums from any data. Such codes are useful, for example, in payment applications, where the checksum verifies that data has not been changed. Also the hash codes taken from file contents are useful for checking if the file content is changed or not.

• Message Digest provides applications the functionality of a message digest algorithm, such as MD5 or SHA. Message digests are secure one-way hash functions that take arbitrary-sized data and output a fixed-length hash value.
• Message Authentication Code (MAC)
  Since everyone can generate the message digest, it may not be suitable for some security related applications. Because of this, Anvil also supports HMAC (rfc2104), which is a mechanism for message authentication using a (secret) key. So you can use a key with a hash algorithm to produce hashes that can only be verified using the same key.

Example. Compute the MD5 digest and hmac and print them out as hex.

 key = "Jefe";
 data = "what do ya want for nothing?";
 digest = crypto.MD5().update(data).final().toHex();
 hmac = crypto.MD5(key).update(data).final().toHex();
 print "The digest is "+digest;
 print "The hmac is "+hmac;
 

 The digest is d03cb659cbf9192dcd066272249f8412
 The hmac is 750c783e6ab0b503eaa86e310a5db738
 

Encryption

Anvil crypto library can also encrypt and decrypt data using DES, TripleDes and Blowfish algorithms.

Example. Encrypt and decrypt a data string using DES.

 key = "Jefe1234";
 data1 = "what do ya want ";
 data2 = "for nothing?";
 cipher = crypto.encrypt(crypto.DES, key);
 crypted = cipher.update(data1);
 crypted = crypted.concat(cipher.update(data2));
 crypted = crypted.concat(cipher.final());
 recovered = crypto.decrypt(crypto.DES, key).final(crypted);