libraryDocs / crypto / hmac

crypto.hmac

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Hash-based Message Authentication Code library.

See RFC 2104 for the algorithm.

Fields

Name	Type	Description
`md5`		Computes a hmac using the MD5 hashing.
`sha1`		Computes a hmac using the SHA-1 hashing.
`sha256`		Computes a hmac using the SHA-256 hashing.
`sha384`		Computes a hmac using the SHA-384 hashing.
`sha512`		Computes a hmac using the SHA-512 hashing.

Functions

`crypto.hmac.digest`	Computes hmac of the message using the given hash function.
`crypto.hmac.digestWithPads`	Computes hmac of the message using precomputed pads from hmac.pads.
`crypto.hmac.normalizeKey`	Normalizes the key to the block size of the hash function.
`crypto.hmac.pads`	Computes the outer and inner pads of the key, key ⊕ opad and key ⊕ ipad.
`crypto.hmac.preset`	Returns a function that computes hmac using the given hash class.

#crypto.hmac.digest

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function crypto.hmac.digest(message: string, key: string, digest_fn: fun( data: string, as_hex: boolean? ): string, block_size: integer, as_hex?: boolean): string

Computes hmac of the message using the given hash function.

Parameters

Name	Type	Description
`message`	`string`	The message to compute hmac for.
`key`	`string`	The key to use.
`digest_fn`	`fun( data: string, as_hex: boolean? ): string`	The hash function to use.
`block_size`	`integer`	The block size of the hash function.
`as_hex`optional	`boolean`	`true` if the result should be a hex string, `false` otherwise.

Returns

Type	Name	Description
`string`	`hmac_str`	The hmac string of the message.

#crypto.hmac.digestWithPads

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function crypto.hmac.digestWithPads(message: string, outer: string, inner: string, digest_fn: fun( data: string, as_hex: boolean? ): string, as_hex?: boolean): string

Computes hmac of the message using precomputed pads from hmac.pads.

Parameters

Name	Type	Description
`message`	`string`	The message to compute hmac for.
`outer`	`string`	The outer pad.
`inner`	`string`	The inner pad.
`digest_fn`	`fun( data: string, as_hex: boolean? ): string`	The hash function to use.
`as_hex`optional	`boolean`	`true` if the result should be a hex string, `false` otherwise.

Returns

Type	Name	Description
`string`	`hmac_str`	The hmac string of the message.

#crypto.hmac.normalizeKey

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function crypto.hmac.normalizeKey(key: string, digest_fn: fun( data: string ): string, block_size: integer): string

Normalizes the key to the block size of the hash function.

Keys longer than block_size are hashed first, shorter keys are padded with zero bytes.

Parameters

Name	Type	Description
`key`	`string`	The key to normalize.
`digest_fn`	`fun( data: string ): string`	The hash function to use.
`block_size`	`integer`	The block size of the hash function.

Returns

Type	Name	Description
`string`	`normalized_key`	The key of exactly `block_size` bytes.

#crypto.hmac.pads

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function crypto.hmac.pads(key: string, block_size: integer): string, string

Computes the outer and inner pads of the key, key ⊕ opad and key ⊕ ipad.

The pads can be computed once and reused with hmac.digestWithPads for many messages under the same key.

Parameters

Name	Type	Description
`key`	`string`	The key normalized by `hmac.normalizeKey`, must be exactly `block_size` bytes.
`block_size`	`integer`	The block size of the hash function.

Returns

Type	Name	Description
`string`	`outer`	The outer pad.
`string`	`inner`	The inner pad.

#crypto.hmac.preset

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function crypto.hmac.preset(hash: crypto.HashClass): fun( message: string, key: string, as_hex: boolean? ): string

Returns a function that computes hmac using the given hash class.

Parameters

Name	Type	Description
`hash`	`crypto.HashClass`	The hash class to use, e.g. `crypto.SHA256`.

Returns

Type	Name	Description
`fun( message: string, key: string, as_hex: boolean? ): string`