63 lines
1.3 KiB
Go
63 lines
1.3 KiB
Go
package verifcid
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import (
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"fmt"
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cid "github.com/ipfs/go-cid"
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mh "github.com/multiformats/go-multihash"
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)
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var ErrPossiblyInsecureHashFunction = fmt.Errorf("potentially insecure hash functions not allowed")
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var ErrBelowMinimumHashLength = fmt.Errorf("hashes must be at %d least bytes long", minimumHashLength)
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const minimumHashLength = 20
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var goodset = map[uint64]bool{
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mh.SHA2_256: true,
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mh.SHA2_512: true,
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mh.SHA3_224: true,
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mh.SHA3_256: true,
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mh.SHA3_384: true,
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mh.SHA3_512: true,
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mh.SHAKE_256: true,
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mh.DBL_SHA2_256: true,
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mh.KECCAK_224: true,
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mh.KECCAK_256: true,
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mh.KECCAK_384: true,
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mh.KECCAK_512: true,
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mh.ID: true,
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mh.SHA1: true, // not really secure but still useful
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}
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func IsGoodHash(code uint64) bool {
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good, found := goodset[code]
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if good {
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return true
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}
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if !found {
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if code >= mh.BLAKE2B_MIN+19 && code <= mh.BLAKE2B_MAX {
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return true
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}
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if code >= mh.BLAKE2S_MIN+19 && code <= mh.BLAKE2S_MAX {
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return true
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}
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}
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return false
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}
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func ValidateCid(c cid.Cid) error {
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pref := c.Prefix()
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if !IsGoodHash(pref.MhType) {
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return ErrPossiblyInsecureHashFunction
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}
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if pref.MhType != mh.ID && pref.MhLength < minimumHashLength {
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return ErrBelowMinimumHashLength
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}
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return nil
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}
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