nodemcu-firmware/docs/modules/crypto.md

crypto Module

Since	Origin / Contributor	Maintainer	Source
2019-01-13	Javier Peletier, Johny Mattsson	Javier Peletier	crypto.c

The crypto module provides various functions for working with cryptographic algorithms.

The following algorithms are supported, both in digest mode and in HMAC mode:

• MD5
• SHA1
• RIPEMD160
• SHA224
• SHA256
• SHA384
• SHA512

crypto.new_hash()

Create a digest/hash object that can have any number of strings added to it.

The returned object has update(str) and finalize() functions, for streaming data through the hash function, and for finalizing and returning the resulting digest.

Syntax

hashobj = crypto.new_hash(algo)

Parameters

• algo the hash algorithm to use, case insensitive string

Returns

Hasher object with update and finalize functions available.

Example

hashobj = crypto.new_hash("SHA1")
hashobj:update("FirstString")
hashobj:update("SecondString")
digest = hashobj:finalize()
print(encoder.toHex(digest))

crypto.new_hmac()

Create an object for calculating a HMAC (Hashed Message Authentication Code, aka "signature"). A HMAC can be used to simultaneously verify both integrity and authenticity of data.

The returned object has update(str) and finalize() functions, for streaming data through the hash function, and for finalizing and returning the resulting signature.

Syntax

hashobj = crypto.new_hmac(algo, key)

Parameters

• algo the hash algorithm to use, case insensitive string
• key the signing key (may be a binary string)

Returns

Hasher object with update and finalize functions available.

Example

hmac = crypto.new_hmac("SHA1", "top s3cr3t key")
hmac:update("Some data")
hmac:update("... more data")
signature = hmac:finalize()
print(encoder.toHex(signature))