111 lines
2.7 KiB
Markdown
111 lines
2.7 KiB
Markdown
# crypto Module
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The crypto modules provides various functions for working with cryptographic algorithms.
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## crypto.hash()
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Compute a cryptographic hash of a Lua string.
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#### Syntax
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`hash = crypto.hash(algo, str)`
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#### Parameters
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`algo` the hash algorithm to use, case insensitive string
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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A binary string containing the message digest. To obtain the textual version (ASCII hex characters), please use [`crypto.toHex()`](#cryptotohex ).
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#### Example
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```lua
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print(crypto.toHex(crypto.hash("sha1","abc")))
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```
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## crypto.hmac()
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Compute a [HMAC](https://en.wikipedia.org/wiki/Hash-based_message_authentication_code) (Hashed Message Authentication Code) signature for a Lua string.
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#### Syntax
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`signature = crypto.hmac(algo, str, key)`
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#### Parameters
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- `algo` hash algorithm to use, case insensitive string
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- `str` data to calculate the hash for
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- `key` key to use for signing, may be a binary string
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Supported hash algorithms are:
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- MD2 (not available by default, has to be explicitly enabled in `app/include/user_config.h`)
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- MD5
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- SHA1
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- SHA256, SHA384, SHA512 (unless disabled in `app/include/user_config.h`)
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#### Returns
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A binary string containing the HMAC signature. Use [`crypto.toHex()`](#cryptotohex ) to obtain the textual version.
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#### Example
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```lua
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print(crypto.toHex(crypto.hmac("sha1","abc","mysecret")))
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```
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## crypto.mask()
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Applies an XOR mask to a Lua string. Note that this is not a proper cryptographic mechanism, but some protocols may use it nevertheless.
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#### Syntax
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`crypto.mask(message, mask)`
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#### Parameters
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- `message` message to mask
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- `mask` the mask to apply, repeated if shorter than the message
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#### Returns
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The masked message, as a binary string. Use [`crypto.toHex()`](#cryptotohex) to get a textual representation of it.
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#### Example
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```lua
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print(crypto.toHex(crypto.mask("some message to obscure","X0Y7")))
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```
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## crypto.toBase64()
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Provides a Base64 representation of a (binary) Lua string.
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#### Syntax
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`b64 = crypto.toBase64(binary)`
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#### Parameters
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`binary` input string to Base64 encode
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#### Return
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A Base64 encoded string.
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#### Example
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```lua
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print(crypto.toBase64(crypto.hash("sha1","abc")))
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```
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## crypto.toHex()
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Provides an ASCII hex representation of a (binary) Lua string. Each byte in the input string is represented as two hex characters in the output.
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#### Syntax
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`hexstr = crypto.toHex(binary)`
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#### Parameters
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`binary` input string to get hex representation for
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#### Returns
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An ASCII hex string.
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#### Example
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```lua
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print(crypto.toHex(crypto.hash("sha1","abc")))
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```
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