96797fed31
- Unify the hashing code for repository and user avatars into a function. - Use a sane hash function instead of MD5. - Only require hashing once instead of twice(w.r.t. hashing for user avatar). - Improve the comment for the hashing code of why it works. Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com> Co-authored-by: Yarden Shoham <hrsi88@gmail.com>
29 lines
978 B
Go
29 lines
978 B
Go
// Copyright 2023 The Gitea Authors. All rights reserved.
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// SPDX-License-Identifier: MIT
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package avatar
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import (
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"crypto/sha256"
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"encoding/hex"
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"strconv"
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)
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// HashAvatar will generate a unique string, which ensures that when there's a
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// different unique ID while the data is the same, it will generate a different
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// output. It will generate the output according to:
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// HEX(HASH(uniqueID || - || data))
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// The hash being used is SHA256.
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// The sole purpose of the unique ID is to generate a distinct hash Such that
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// two unique IDs with the same data will have a different hash output.
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// The "-" byte is important to ensure that data cannot be modified such that
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// the first byte is a number, which could lead to a "collision" with the hash
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// of another unique ID.
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func HashAvatar(uniqueID int64, data []byte) string {
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h := sha256.New()
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h.Write([]byte(strconv.FormatInt(uniqueID, 10)))
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h.Write([]byte{'-'})
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h.Write(data)
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return hex.EncodeToString(h.Sum(nil))
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}
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