45 lines
1.3 KiB
V
45 lines
1.3 KiB
V
// HMAC: Keyed-Hashing for Message Authentication implemented in v
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// implementation based on https://tools.ietf.org/html/rfc2104
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module hmac
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import crypto.internal.subtle
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const (
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ipad = []byte{len: 256, init: 0x36} // TODO is 256 enough??
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opad = []byte{len: 256, init: 0x5C}
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npad = []byte{len: 256, init: 0}
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)
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// new returns a HMAC byte array, depending on the hash algorithm used.
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pub fn new(key []byte, data []byte, hash_func fn ([]byte) []byte, blocksize int) []byte {
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mut b_key := []byte{}
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if key.len <= blocksize {
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b_key = key.clone() // TODO: remove .clone() once https://github.com/vlang/v/issues/6604 gets fixed
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} else {
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b_key = hash_func(key)
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}
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if b_key.len < blocksize {
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b_key << hmac.npad[..blocksize - b_key.len]
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}
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mut inner := []byte{}
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for i, b in hmac.ipad[..blocksize] {
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inner << b_key[i] ^ b
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}
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inner << data
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inner_hash := hash_func(inner)
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mut outer := []byte{cap: b_key.len}
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for i, b in hmac.opad[..blocksize] {
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outer << b_key[i] ^ b
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}
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outer << inner_hash
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digest := hash_func(outer)
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return digest
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}
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// equal compares 2 MACs for equality, without leaking timing info.
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// Note: if the lengths of the 2 MACs are different, probably a completely different
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// hash function was used to generate them => no useful timing information.
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pub fn equal(mac1 []byte, mac2 []byte) bool {
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return subtle.constant_time_compare(mac1, mac2) == 1
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}
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