encrypt using rsa

Typecommand
DictionaryLCS
LibraryLiveCode Script
Syntax
encrypt <message> using rsa with {public | private} key <key> [and passphrase <passphrase>]
Summary

Encrypt data using the RSA algorithm.

Introduced4.6
OSmac, windows, linux, ios, android
Platformsdesktop, server, mobile
Parameters
NameTypeDescription
key

The key to be used for the encryption, in PEM format

passphrase

An optional passphrase

message

The message to be encrypted

Example
encrypt myMessage using rsa with public key myKey
encrypt thisMessage using rsa with private key privateKey
RelatedCommand: decrypt, encrypt, decrypt using rsa
Securitynetwork
Description

Use the encrypt using rsa command to encrypt a message using RSA public key encryption.

To encode a message that you only want to be decoded by the holder of the private key, use the form:

encrypt <a href="message_LCS_glossary.html">message</a> with public key <a href="key_LCS_glossary.html">key</a> 

As a signing operation, to encode a message that a receiver can then verify has come from one of the holders of the private key, use the form:

encrypt <a href="message_LCS_glossary.html">message</a> with private key <a href="key_LCS_glossary.html">key</a> 

Generating key pairs

Public-private key pairs can be generated using the OpenSSL suite of command-line tools. For example: openssl genrsa -out private_key.pem 512 openssl rsa -pubout -in private_key.pem -out public_key.pem Will generate a key pair of size 512-bits, placing the private key in private_key.pem and the public key in public_key.pem.

For more information on these utilities see https://www.openssl.org/docs/manmaster/man1/rsa.html and https://www.openssl.org/docs/manmaster/man1/genrsa.html.

Note: The maximum length of a message that can be encrypted using RSA is the size of the key in bytes -11. So, for a 512-bit key pair, the maximum encryptable message size is 53 bytes.

For signing, the maximum length of an encryptable message isn't really an issue since typically in that scenario it will be some sort of hash that would be being encrypted. For the more traditional encrypting scenario, however, the standard approach is to use public key cryptography to encrypt a random password which is then used with a symmetric cipher to actually encrypt the payload.